diff mbox series

[v4,05/11] drm/msm/A6xx: Implement preemption for A7XX targets

Message ID 20240917-preemption-a750-t-v4-5-95d48012e0ac@gmail.com (mailing list archive)
State New, archived
Headers show
Series Preemption support for A7XX | expand

Commit Message

Antonino Maniscalco Sept. 17, 2024, 11:14 a.m. UTC
This patch implements preemption feature for A6xx targets, this allows
the GPU to switch to a higher priority ringbuffer if one is ready. A6XX
hardware as such supports multiple levels of preemption granularities,
ranging from coarse grained(ringbuffer level) to a more fine grained
such as draw-call level or a bin boundary level preemption. This patch
enables the basic preemption level, with more fine grained preemption
support to follow.

Signed-off-by: Sharat Masetty <smasetty@codeaurora.org>
Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
---
 drivers/gpu/drm/msm/Makefile              |   1 +
 drivers/gpu/drm/msm/adreno/a6xx_gpu.c     | 283 +++++++++++++++++++++-
 drivers/gpu/drm/msm/adreno/a6xx_gpu.h     | 168 +++++++++++++
 drivers/gpu/drm/msm/adreno/a6xx_preempt.c | 377 ++++++++++++++++++++++++++++++
 drivers/gpu/drm/msm/msm_ringbuffer.h      |   7 +
 5 files changed, 825 insertions(+), 11 deletions(-)

Comments

Akhil P Oommen Sept. 20, 2024, 4:37 p.m. UTC | #1
On Tue, Sep 17, 2024 at 01:14:15PM +0200, Antonino Maniscalco wrote:
> This patch implements preemption feature for A6xx targets, this allows
> the GPU to switch to a higher priority ringbuffer if one is ready. A6XX
> hardware as such supports multiple levels of preemption granularities,
> ranging from coarse grained(ringbuffer level) to a more fine grained
> such as draw-call level or a bin boundary level preemption. This patch
> enables the basic preemption level, with more fine grained preemption
> support to follow.
> 
> Signed-off-by: Sharat Masetty <smasetty@codeaurora.org>
> Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
> Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
> ---
>  drivers/gpu/drm/msm/Makefile              |   1 +
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.c     | 283 +++++++++++++++++++++-
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.h     | 168 +++++++++++++
>  drivers/gpu/drm/msm/adreno/a6xx_preempt.c | 377 ++++++++++++++++++++++++++++++
>  drivers/gpu/drm/msm/msm_ringbuffer.h      |   7 +
>  5 files changed, 825 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/Makefile b/drivers/gpu/drm/msm/Makefile
> index f5e2838c6a76..32e915109a59 100644
> --- a/drivers/gpu/drm/msm/Makefile
> +++ b/drivers/gpu/drm/msm/Makefile
> @@ -23,6 +23,7 @@ adreno-y := \
>  	adreno/a6xx_gpu.o \
>  	adreno/a6xx_gmu.o \
>  	adreno/a6xx_hfi.o \
> +	adreno/a6xx_preempt.o \
>  
>  adreno-$(CONFIG_DEBUG_FS) += adreno/a5xx_debugfs.o \
>  
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> index 6e065500b64d..355a3e210335 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> @@ -16,6 +16,84 @@
>  
>  #define GPU_PAS_ID 13
>  
> +/* IFPC & Preemption static powerup restore list */
> +static const uint32_t a7xx_pwrup_reglist[] = {
> +	REG_A6XX_UCHE_TRAP_BASE,
> +	REG_A6XX_UCHE_TRAP_BASE + 1,
> +	REG_A6XX_UCHE_WRITE_THRU_BASE,
> +	REG_A6XX_UCHE_WRITE_THRU_BASE + 1,
> +	REG_A6XX_UCHE_GMEM_RANGE_MIN,
> +	REG_A6XX_UCHE_GMEM_RANGE_MIN + 1,
> +	REG_A6XX_UCHE_GMEM_RANGE_MAX,
> +	REG_A6XX_UCHE_GMEM_RANGE_MAX + 1,
> +	REG_A6XX_UCHE_CACHE_WAYS,
> +	REG_A6XX_UCHE_MODE_CNTL,
> +	REG_A6XX_RB_NC_MODE_CNTL,
> +	REG_A6XX_RB_CMP_DBG_ECO_CNTL,
> +	REG_A7XX_GRAS_NC_MODE_CNTL,
> +	REG_A6XX_RB_CONTEXT_SWITCH_GMEM_SAVE_RESTORE,
> +	REG_A6XX_UCHE_GBIF_GX_CONFIG,
> +	REG_A6XX_UCHE_CLIENT_PF,
> +	REG_A6XX_TPL1_DBG_ECO_CNTL1,
> +};
> +
> +static const uint32_t a7xx_ifpc_pwrup_reglist[] = {
> +	REG_A6XX_TPL1_NC_MODE_CNTL,
> +	REG_A6XX_SP_NC_MODE_CNTL,
> +	REG_A6XX_CP_DBG_ECO_CNTL,
> +	REG_A6XX_CP_PROTECT_CNTL,
> +	REG_A6XX_CP_PROTECT(0),
> +	REG_A6XX_CP_PROTECT(1),
> +	REG_A6XX_CP_PROTECT(2),
> +	REG_A6XX_CP_PROTECT(3),
> +	REG_A6XX_CP_PROTECT(4),
> +	REG_A6XX_CP_PROTECT(5),
> +	REG_A6XX_CP_PROTECT(6),
> +	REG_A6XX_CP_PROTECT(7),
> +	REG_A6XX_CP_PROTECT(8),
> +	REG_A6XX_CP_PROTECT(9),
> +	REG_A6XX_CP_PROTECT(10),
> +	REG_A6XX_CP_PROTECT(11),
> +	REG_A6XX_CP_PROTECT(12),
> +	REG_A6XX_CP_PROTECT(13),
> +	REG_A6XX_CP_PROTECT(14),
> +	REG_A6XX_CP_PROTECT(15),
> +	REG_A6XX_CP_PROTECT(16),
> +	REG_A6XX_CP_PROTECT(17),
> +	REG_A6XX_CP_PROTECT(18),
> +	REG_A6XX_CP_PROTECT(19),
> +	REG_A6XX_CP_PROTECT(20),
> +	REG_A6XX_CP_PROTECT(21),
> +	REG_A6XX_CP_PROTECT(22),
> +	REG_A6XX_CP_PROTECT(23),
> +	REG_A6XX_CP_PROTECT(24),
> +	REG_A6XX_CP_PROTECT(25),
> +	REG_A6XX_CP_PROTECT(26),
> +	REG_A6XX_CP_PROTECT(27),
> +	REG_A6XX_CP_PROTECT(28),
> +	REG_A6XX_CP_PROTECT(29),
> +	REG_A6XX_CP_PROTECT(30),
> +	REG_A6XX_CP_PROTECT(31),
> +	REG_A6XX_CP_PROTECT(32),
> +	REG_A6XX_CP_PROTECT(33),
> +	REG_A6XX_CP_PROTECT(34),
> +	REG_A6XX_CP_PROTECT(35),
> +	REG_A6XX_CP_PROTECT(36),
> +	REG_A6XX_CP_PROTECT(37),
> +	REG_A6XX_CP_PROTECT(38),
> +	REG_A6XX_CP_PROTECT(39),
> +	REG_A6XX_CP_PROTECT(40),
> +	REG_A6XX_CP_PROTECT(41),
> +	REG_A6XX_CP_PROTECT(42),
> +	REG_A6XX_CP_PROTECT(43),
> +	REG_A6XX_CP_PROTECT(44),
> +	REG_A6XX_CP_PROTECT(45),
> +	REG_A6XX_CP_PROTECT(46),
> +	REG_A6XX_CP_PROTECT(47),
> +	REG_A6XX_CP_AHB_CNTL,
> +};
> +
> +
>  static inline bool _a6xx_check_idle(struct msm_gpu *gpu)
>  {
>  	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
> @@ -68,6 +146,8 @@ static void update_shadow_rptr(struct msm_gpu *gpu, struct msm_ringbuffer *ring)
>  
>  static void a6xx_flush(struct msm_gpu *gpu, struct msm_ringbuffer *ring)
>  {
> +	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
> +	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
>  	uint32_t wptr;
>  	unsigned long flags;
>  
> @@ -81,12 +161,17 @@ static void a6xx_flush(struct msm_gpu *gpu, struct msm_ringbuffer *ring)
>  	/* Make sure to wrap wptr if we need to */
>  	wptr = get_wptr(ring);
>  
> -	spin_unlock_irqrestore(&ring->preempt_lock, flags);
> -
> -	/* Make sure everything is posted before making a decision */
> -	mb();
> +	/* Update HW if this is the current ring and we are not in preempt*/
> +	if (!a6xx_in_preempt(a6xx_gpu)) {
> +		if (a6xx_gpu->cur_ring == ring)
> +			gpu_write(gpu, REG_A6XX_CP_RB_WPTR, wptr);
> +		else
> +			ring->restore_wptr = true;
> +	} else {
> +		ring->restore_wptr = true;
> +	}
>  
> -	gpu_write(gpu, REG_A6XX_CP_RB_WPTR, wptr);
> +	spin_unlock_irqrestore(&ring->preempt_lock, flags);
>  }
>  
>  static void get_stats_counter(struct msm_ringbuffer *ring, u32 counter,
> @@ -138,12 +223,14 @@ static void a6xx_set_pagetable(struct a6xx_gpu *a6xx_gpu,
>  
>  	/*
>  	 * Write the new TTBR0 to the memstore. This is good for debugging.
> +	 * Needed for preemption
>  	 */
> -	OUT_PKT7(ring, CP_MEM_WRITE, 4);
> +	OUT_PKT7(ring, CP_MEM_WRITE, 5);
>  	OUT_RING(ring, CP_MEM_WRITE_0_ADDR_LO(lower_32_bits(memptr)));
>  	OUT_RING(ring, CP_MEM_WRITE_1_ADDR_HI(upper_32_bits(memptr)));
>  	OUT_RING(ring, lower_32_bits(ttbr));
> -	OUT_RING(ring, (asid << 16) | upper_32_bits(ttbr));
> +	OUT_RING(ring, upper_32_bits(ttbr));
> +	OUT_RING(ring, ctx->seqno);
>  
>  	/*
>  	 * Sync both threads after switching pagetables and enable BR only
> @@ -268,6 +355,34 @@ static void a6xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
>  	a6xx_flush(gpu, ring);
>  }
>  
> +static void a6xx_emit_set_pseudo_reg(struct msm_ringbuffer *ring,
> +		struct a6xx_gpu *a6xx_gpu, struct msm_gpu_submitqueue *queue)
> +{
> +	OUT_PKT7(ring, CP_SET_PSEUDO_REG, 12);
> +
> +	OUT_RING(ring, SMMU_INFO);
> +	/* don't save SMMU, we write the record from the kernel instead */
> +	OUT_RING(ring, 0);
> +	OUT_RING(ring, 0);
> +
> +	/* privileged and non secure buffer save */
> +	OUT_RING(ring, NON_SECURE_SAVE_ADDR);
> +	OUT_RING(ring, lower_32_bits(
> +		a6xx_gpu->preempt_iova[ring->id] + PREEMPT_OFFSET_PRIV_NON_SECURE));
> +	OUT_RING(ring, upper_32_bits(
> +		a6xx_gpu->preempt_iova[ring->id] + PREEMPT_OFFSET_PRIV_NON_SECURE));
> +
> +	/* user context buffer save, seems to be unnused by fw */
> +	OUT_RING(ring, NON_PRIV_SAVE_ADDR);
> +	OUT_RING(ring, 0);
> +	OUT_RING(ring, 0);
> +
> +	OUT_RING(ring, COUNTER);
> +	/* seems OK to set to 0 to disable it */
> +	OUT_RING(ring, 0);
> +	OUT_RING(ring, 0);
> +}
> +
>  static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
>  {
>  	unsigned int index = submit->seqno % MSM_GPU_SUBMIT_STATS_COUNT;
> @@ -285,6 +400,13 @@ static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
>  
>  	a6xx_set_pagetable(a6xx_gpu, ring, submit->queue->ctx);
>  
> +	/*
> +	 * If preemption is enabled, then set the pseudo register for the save
> +	 * sequence
> +	 */
> +	if (gpu->nr_rings > 1)
> +		a6xx_emit_set_pseudo_reg(ring, a6xx_gpu, submit->queue);
> +
>  	get_stats_counter(ring, REG_A7XX_RBBM_PERFCTR_CP(0),
>  		rbmemptr_stats(ring, index, cpcycles_start));
>  	get_stats_counter(ring, REG_A6XX_CP_ALWAYS_ON_COUNTER,
> @@ -376,6 +498,8 @@ static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
>  	OUT_RING(ring, upper_32_bits(rbmemptr(ring, bv_fence)));
>  	OUT_RING(ring, submit->seqno);
>  
> +	a6xx_gpu->last_seqno[ring->id] = submit->seqno;
> +
>  	/* write the ringbuffer timestamp */
>  	OUT_PKT7(ring, CP_EVENT_WRITE, 4);
>  	OUT_RING(ring, CACHE_CLEAN | CP_EVENT_WRITE_0_IRQ | BIT(27));
> @@ -389,10 +513,32 @@ static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
>  	OUT_PKT7(ring, CP_SET_MARKER, 1);
>  	OUT_RING(ring, 0x100); /* IFPC enable */
>  
> +	/* If preemption is enabled */
> +	if (gpu->nr_rings > 1) {
> +		/* Yield the floor on command completion */
> +		OUT_PKT7(ring, CP_CONTEXT_SWITCH_YIELD, 4);
> +
> +		/*
> +		 * If dword[2:1] are non zero, they specify an address for
> +		 * the CP to write the value of dword[3] to on preemption
> +		 * complete. Write 0 to skip the write
> +		 */
> +		OUT_RING(ring, 0x00);
> +		OUT_RING(ring, 0x00);
> +		/* Data value - not used if the address above is 0 */
> +		OUT_RING(ring, 0x01);
> +		/* generate interrupt on preemption completion */
> +		OUT_RING(ring, 0x00);
> +	}
> +
> +
>  	trace_msm_gpu_submit_flush(submit,
>  		gpu_read64(gpu, REG_A6XX_CP_ALWAYS_ON_COUNTER));
>  
>  	a6xx_flush(gpu, ring);
> +
> +	/* Check to see if we need to start preemption */
> +	a6xx_preempt_trigger(gpu);
>  }
>  
>  static void a6xx_set_hwcg(struct msm_gpu *gpu, bool state)
> @@ -588,6 +734,89 @@ static void a6xx_set_ubwc_config(struct msm_gpu *gpu)
>  		  adreno_gpu->ubwc_config.min_acc_len << 23 | hbb_lo << 21);
>  }
>  
> +static void a7xx_patch_pwrup_reglist(struct msm_gpu *gpu)
> +{
> +	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
> +	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
> +	struct adreno_reglist_list reglist[2];
> +	void *ptr = a6xx_gpu->pwrup_reglist_ptr;
> +	struct cpu_gpu_lock *lock = ptr;
> +	u32 *dest = (u32 *)&lock->regs[0];
> +	int i, j;
> +
> +	lock->gpu_req = lock->cpu_req = lock->turn = 0;
> +	lock->ifpc_list_len = ARRAY_SIZE(a7xx_ifpc_pwrup_reglist);
> +	lock->preemption_list_len = ARRAY_SIZE(a7xx_pwrup_reglist);
> +
> +	/* Static IFPC-only registers */
> +	reglist[0].regs = a7xx_ifpc_pwrup_reglist;
> +	reglist[0].count = ARRAY_SIZE(a7xx_ifpc_pwrup_reglist);
> +	lock->ifpc_list_len = reglist[0].count;
> +
> +	/* Static IFPC + preemption registers */
> +	reglist[1].regs = a7xx_pwrup_reglist;
> +	reglist[1].count = ARRAY_SIZE(a7xx_pwrup_reglist);
> +	lock->preemption_list_len = reglist[1].count;
> +
> +	/*
> +	 * For each entry in each of the lists, write the offset and the current
> +	 * register value into the GPU buffer
> +	 */
> +	for (i = 0; i < 2; i++) {
> +		const u32 *r = reglist[i].regs;
> +
> +		for (j = 0; j < reglist[i].count; j++) {
> +			*dest++ = r[j];
> +			*dest++ = gpu_read(gpu, r[j]);
> +		}
> +	}
> +
> +	/*
> +	 * The overall register list is composed of
> +	 * 1. Static IFPC-only registers
> +	 * 2. Static IFPC + preemption registers
> +	 * 3. Dynamic IFPC + preemption registers (ex: perfcounter selects)
> +	 *
> +	 * The first two lists are static. Size of these lists are stored as
> +	 * number of pairs in ifpc_list_len and preemption_list_len
> +	 * respectively. With concurrent binning, Some of the perfcounter
> +	 * registers being virtualized, CP needs to know the pipe id to program
> +	 * the aperture inorder to restore the same. Thus, third list is a
> +	 * dynamic list with triplets as
> +	 * (<aperture, shifted 12 bits> <address> <data>), and the length is
> +	 * stored as number for triplets in dynamic_list_len.
> +	 */
> +	lock->dynamic_list_len = 0;
> +}
> +
> +static int a7xx_preempt_start(struct msm_gpu *gpu)
> +{
> +	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
> +	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
> +	struct msm_ringbuffer *ring = gpu->rb[0];
> +
> +	if (gpu->nr_rings <= 1)
> +		return 0;
> +
> +	/* Turn CP protection off */
> +	OUT_PKT7(ring, CP_SET_PROTECTED_MODE, 1);
> +	OUT_RING(ring, 0);
> +
> +	a6xx_emit_set_pseudo_reg(ring, a6xx_gpu, NULL);
> +
> +	/* Yield the floor on command completion */
> +	OUT_PKT7(ring, CP_CONTEXT_SWITCH_YIELD, 4);
> +	OUT_RING(ring, 0x00);
> +	OUT_RING(ring, 0x00);
> +	OUT_RING(ring, 0x00);
> +	/* Generate interrupt on preemption completion */
> +	OUT_RING(ring, 0x00);
> +
> +	a6xx_flush(gpu, ring);
> +
> +	return a6xx_idle(gpu, ring) ? 0 : -EINVAL;
> +}
> +
>  static int a6xx_cp_init(struct msm_gpu *gpu)
>  {
>  	struct msm_ringbuffer *ring = gpu->rb[0];
> @@ -619,6 +848,8 @@ static int a6xx_cp_init(struct msm_gpu *gpu)
>  
>  static int a7xx_cp_init(struct msm_gpu *gpu)
>  {
> +	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
> +	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
>  	struct msm_ringbuffer *ring = gpu->rb[0];
>  	u32 mask;
>  
> @@ -656,11 +887,11 @@ static int a7xx_cp_init(struct msm_gpu *gpu)
>  
>  	/* *Don't* send a power up reg list for concurrent binning (TODO) */
>  	/* Lo address */
> -	OUT_RING(ring, 0x00000000);
> +	OUT_RING(ring, lower_32_bits(a6xx_gpu->pwrup_reglist_iova));
>  	/* Hi address */
> -	OUT_RING(ring, 0x00000000);
> +	OUT_RING(ring, upper_32_bits(a6xx_gpu->pwrup_reglist_iova));
>  	/* BIT(31) set => read the regs from the list */
> -	OUT_RING(ring, 0x00000000);
> +	OUT_RING(ring, BIT(31));
>  
>  	a6xx_flush(gpu, ring);
>  	return a6xx_idle(gpu, ring) ? 0 : -EINVAL;
> @@ -784,6 +1015,16 @@ static int a6xx_ucode_load(struct msm_gpu *gpu)
>  		msm_gem_object_set_name(a6xx_gpu->shadow_bo, "shadow");
>  	}
>  
> +	a6xx_gpu->pwrup_reglist_ptr = msm_gem_kernel_new(gpu->dev, PAGE_SIZE,
> +							 MSM_BO_WC  | MSM_BO_MAP_PRIV,
> +							 gpu->aspace, &a6xx_gpu->pwrup_reglist_bo,
> +							 &a6xx_gpu->pwrup_reglist_iova);
> +
> +	if (IS_ERR(a6xx_gpu->pwrup_reglist_ptr))
> +		return PTR_ERR(a6xx_gpu->pwrup_reglist_ptr);
> +
> +	msm_gem_object_set_name(a6xx_gpu->pwrup_reglist_bo, "pwrup_reglist");
> +
>  	return 0;
>  }
>  
> @@ -1128,6 +1369,8 @@ static int hw_init(struct msm_gpu *gpu)
>  	if (a6xx_gpu->shadow_bo) {
>  		gpu_write64(gpu, REG_A6XX_CP_RB_RPTR_ADDR,
>  			shadowptr(a6xx_gpu, gpu->rb[0]));
> +		for (unsigned int i = 0; i < gpu->nr_rings; i++)
> +			a6xx_gpu->shadow[i] = 0;
>  	}
>  
>  	/* ..which means "always" on A7xx, also for BV shadow */
> @@ -1136,6 +1379,8 @@ static int hw_init(struct msm_gpu *gpu)
>  			    rbmemptr(gpu->rb[0], bv_rptr));
>  	}
>  
> +	a6xx_preempt_hw_init(gpu);
> +
>  	/* Always come up on rb 0 */
>  	a6xx_gpu->cur_ring = gpu->rb[0];
>  
> @@ -1145,6 +1390,11 @@ static int hw_init(struct msm_gpu *gpu)
>  	/* Enable the SQE_to start the CP engine */
>  	gpu_write(gpu, REG_A6XX_CP_SQE_CNTL, 1);
>  
> +	if (adreno_is_a7xx(adreno_gpu) && !a6xx_gpu->pwrup_reglist_emitted) {
> +		a7xx_patch_pwrup_reglist(gpu);
> +		a6xx_gpu->pwrup_reglist_emitted = true;
> +	}
> +
>  	ret = adreno_is_a7xx(adreno_gpu) ? a7xx_cp_init(gpu) : a6xx_cp_init(gpu);
>  	if (ret)
>  		goto out;
> @@ -1182,6 +1432,10 @@ static int hw_init(struct msm_gpu *gpu)
>  out:
>  	if (adreno_has_gmu_wrapper(adreno_gpu))
>  		return ret;
> +
> +	/* Last step - yield the ringbuffer */
> +	a7xx_preempt_start(gpu);
> +
>  	/*
>  	 * Tell the GMU that we are done touching the GPU and it can start power
>  	 * management
> @@ -1559,8 +1813,13 @@ static irqreturn_t a6xx_irq(struct msm_gpu *gpu)
>  	if (status & A6XX_RBBM_INT_0_MASK_SWFUSEVIOLATION)
>  		a7xx_sw_fuse_violation_irq(gpu);
>  
> -	if (status & A6XX_RBBM_INT_0_MASK_CP_CACHE_FLUSH_TS)
> +	if (status & A6XX_RBBM_INT_0_MASK_CP_CACHE_FLUSH_TS) {
>  		msm_gpu_retire(gpu);
> +		a6xx_preempt_trigger(gpu);
> +	}
> +
> +	if (status & A6XX_RBBM_INT_0_MASK_CP_SW)
> +		a6xx_preempt_irq(gpu);
>  
>  	return IRQ_HANDLED;
>  }
> @@ -2333,6 +2592,8 @@ struct msm_gpu *a6xx_gpu_init(struct drm_device *dev)
>  				a6xx_fault_handler);
>  
>  	a6xx_calc_ubwc_config(adreno_gpu);
> +	/* Set up the preemption specific bits and pieces for each ringbuffer */
> +	a6xx_preempt_init(gpu);
>  
>  	return gpu;
>  }
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
> index e3e5c53ae8af..7fc994121676 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
> @@ -12,6 +12,31 @@
>  
>  extern bool hang_debug;
>  
> +struct cpu_gpu_lock {
> +	uint32_t gpu_req;
> +	uint32_t cpu_req;
> +	uint32_t turn;
> +	union {
> +		struct {
> +			uint16_t list_length;
> +			uint16_t list_offset;
> +		};
> +		struct {
> +			uint8_t ifpc_list_len;
> +			uint8_t preemption_list_len;
> +			uint16_t dynamic_list_len;
> +		};
> +	};
> +	uint64_t regs[62];
> +};
> +
> +struct adreno_reglist_list {
> +	/** @reg: List of register **/
> +	const u32 *regs;
> +	/** @count: Number of registers in the list **/
> +	u32 count;
> +};
> +
>  /**
>   * struct a6xx_info - a6xx specific information from device table
>   *
> @@ -31,6 +56,20 @@ struct a6xx_gpu {
>  	uint64_t sqe_iova;
>  
>  	struct msm_ringbuffer *cur_ring;
> +	struct msm_ringbuffer *next_ring;
> +
> +	struct drm_gem_object *preempt_bo[MSM_GPU_MAX_RINGS];
> +	void *preempt[MSM_GPU_MAX_RINGS];
> +	uint64_t preempt_iova[MSM_GPU_MAX_RINGS];
> +	uint32_t last_seqno[MSM_GPU_MAX_RINGS];
> +
> +	atomic_t preempt_state;
> +	spinlock_t eval_lock;
> +	struct timer_list preempt_timer;
> +
> +	unsigned int preempt_level;
> +	bool uses_gmem;
> +	bool skip_save_restore;
>  
>  	struct a6xx_gmu gmu;
>  
> @@ -38,6 +77,11 @@ struct a6xx_gpu {
>  	uint64_t shadow_iova;
>  	uint32_t *shadow;
>  
> +	struct drm_gem_object *pwrup_reglist_bo;
> +	void *pwrup_reglist_ptr;
> +	uint64_t pwrup_reglist_iova;
> +	bool pwrup_reglist_emitted;
> +
>  	bool has_whereami;
>  
>  	void __iomem *llc_mmio;
> @@ -49,6 +93,102 @@ struct a6xx_gpu {
>  
>  #define to_a6xx_gpu(x) container_of(x, struct a6xx_gpu, base)
>  
> +/*
> + * In order to do lockless preemption we use a simple state machine to progress
> + * through the process.
> + *
> + * PREEMPT_NONE - no preemption in progress.  Next state START.
> + * PREEMPT_START - The trigger is evaluating if preemption is possible. Next
> + * states: TRIGGERED, NONE
> + * PREEMPT_FINISH - An intermediate state before moving back to NONE. Next
> + * state: NONE.
> + * PREEMPT_TRIGGERED: A preemption has been executed on the hardware. Next
> + * states: FAULTED, PENDING
> + * PREEMPT_FAULTED: A preemption timed out (never completed). This will trigger
> + * recovery.  Next state: N/A
> + * PREEMPT_PENDING: Preemption complete interrupt fired - the callback is
> + * checking the success of the operation. Next state: FAULTED, NONE.
> + */
> +
> +enum a6xx_preempt_state {
> +	PREEMPT_NONE = 0,
> +	PREEMPT_START,
> +	PREEMPT_FINISH,
> +	PREEMPT_TRIGGERED,
> +	PREEMPT_FAULTED,
> +	PREEMPT_PENDING,
> +};
> +
> +/*
> + * struct a6xx_preempt_record is a shared buffer between the microcode and the
> + * CPU to store the state for preemption. The record itself is much larger
> + * (2112k) but most of that is used by the CP for storage.
> + *
> + * There is a preemption record assigned per ringbuffer. When the CPU triggers a
> + * preemption, it fills out the record with the useful information (wptr, ring
> + * base, etc) and the microcode uses that information to set up the CP following
> + * the preemption.  When a ring is switched out, the CP will save the ringbuffer
> + * state back to the record. In this way, once the records are properly set up
> + * the CPU can quickly switch back and forth between ringbuffers by only
> + * updating a few registers (often only the wptr).
> + *
> + * These are the CPU aware registers in the record:
> + * @magic: Must always be 0xAE399D6EUL
> + * @info: Type of the record - written 0 by the CPU, updated by the CP
> + * @errno: preemption error record
> + * @data: Data field in YIELD and SET_MARKER packets, Written and used by CP
> + * @cntl: Value of RB_CNTL written by CPU, save/restored by CP
> + * @rptr: Value of RB_RPTR written by CPU, save/restored by CP
> + * @wptr: Value of RB_WPTR written by CPU, save/restored by CP
> + * @_pad: Reserved/padding
> + * @rptr_addr: Value of RB_RPTR_ADDR_LO|HI written by CPU, save/restored by CP
> + * @rbase: Value of RB_BASE written by CPU, save/restored by CP
> + * @counter: GPU address of the storage area for the preemption counters
> + * @bv_rptr_addr: Value of BV_RB_RPTR_ADDR_LO|HI written by CPU, save/restored by CP
> + */
> +struct a6xx_preempt_record {
> +	u32 magic;
> +	u32 info;
> +	u32 errno;
> +	u32 data;
> +	u32 cntl;
> +	u32 rptr;
> +	u32 wptr;
> +	u32 _pad;
> +	u64 rptr_addr;
> +	u64 rbase;
> +	u64 counter;
> +	u64 bv_rptr_addr;
> +};
> +
> +#define A6XX_PREEMPT_RECORD_MAGIC 0xAE399D6EUL
> +
> +#define PREEMPT_RECORD_SIZE_FALLBACK(size) \
> +	((size) == 0 ? 4192 * SZ_1K : (size))
> +
> +#define PREEMPT_OFFSET_SMMU_INFO 0
> +#define PREEMPT_OFFSET_PRIV_NON_SECURE (PREEMPT_OFFSET_SMMU_INFO + 4096)
> +#define PREEMPT_SIZE(size) \
> +	(PREEMPT_OFFSET_PRIV_NON_SECURE + PREEMPT_RECORD_SIZE_FALLBACK(size))
> +
> +/*
> + * The preemption counter block is a storage area for the value of the
> + * preemption counters that are saved immediately before context switch. We
> + * append it on to the end of the allocation for the preemption record.
> + */
> +#define A6XX_PREEMPT_COUNTER_SIZE (16 * 4)
> +
> +struct a7xx_cp_smmu_info {
> +	u32 magic;
> +	u32 _pad4;
> +	u64 ttbr0;
> +	u32 asid;
> +	u32 context_idr;
> +	u32 context_bank;
> +};
> +
> +#define GEN7_CP_SMMU_INFO_MAGIC 0x241350d5UL
> +
>  /*
>   * Given a register and a count, return a value to program into
>   * REG_CP_PROTECT_REG(n) - this will block both reads and writes for
> @@ -106,6 +246,34 @@ int a6xx_gmu_init(struct a6xx_gpu *a6xx_gpu, struct device_node *node);
>  int a6xx_gmu_wrapper_init(struct a6xx_gpu *a6xx_gpu, struct device_node *node);
>  void a6xx_gmu_remove(struct a6xx_gpu *a6xx_gpu);
>  
> +void a6xx_preempt_init(struct msm_gpu *gpu);
> +void a6xx_preempt_hw_init(struct msm_gpu *gpu);
> +void a6xx_preempt_trigger(struct msm_gpu *gpu);
> +void a6xx_preempt_irq(struct msm_gpu *gpu);
> +void a6xx_preempt_fini(struct msm_gpu *gpu);
> +int a6xx_preempt_submitqueue_setup(struct msm_gpu *gpu,
> +		struct msm_gpu_submitqueue *queue);
> +void a6xx_preempt_submitqueue_close(struct msm_gpu *gpu,
> +		struct msm_gpu_submitqueue *queue);
> +
> +/* Return true if we are in a preempt state */
> +static inline bool a6xx_in_preempt(struct a6xx_gpu *a6xx_gpu)
> +{
> +	/*
> +	 * Make sure the read to preempt_state is ordered with respect to reads
> +	 * of other variables before ...
> +	 */
> +	smp_rmb();
> +
> +	int preempt_state = atomic_read(&a6xx_gpu->preempt_state);
> +
> +	/* ... and after. */
> +	smp_rmb();
> +
> +	return !(preempt_state == PREEMPT_NONE ||
> +			preempt_state == PREEMPT_FINISH);
> +}
> +
>  void a6xx_gmu_set_freq(struct msm_gpu *gpu, struct dev_pm_opp *opp,
>  		       bool suspended);
>  unsigned long a6xx_gmu_get_freq(struct msm_gpu *gpu);
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_preempt.c b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
> new file mode 100644
> index 000000000000..aa4bad394f9e
> --- /dev/null
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
> @@ -0,0 +1,377 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2018, The Linux Foundation. All rights reserved. */
> +/* Copyright (c) 2023 Collabora, Ltd. */
> +/* Copyright (c) 2024 Valve Corporation */
> +
> +#include "msm_gem.h"
> +#include "a6xx_gpu.h"
> +#include "a6xx_gmu.xml.h"
> +#include "msm_mmu.h"
> +
> +/*
> + * Try to transition the preemption state from old to new. Return
> + * true on success or false if the original state wasn't 'old'
> + */
> +static inline bool try_preempt_state(struct a6xx_gpu *a6xx_gpu,
> +		enum a6xx_preempt_state old, enum a6xx_preempt_state new)
> +{
> +	enum a6xx_preempt_state cur = atomic_cmpxchg(&a6xx_gpu->preempt_state,
> +		old, new);
> +
> +	return (cur == old);
> +}
> +
> +/*
> + * Force the preemption state to the specified state.  This is used in cases
> + * where the current state is known and won't change
> + */
> +static inline void set_preempt_state(struct a6xx_gpu *gpu,
> +		enum a6xx_preempt_state new)
> +{
> +	/*
> +	 * preempt_state may be read by other cores trying to trigger a
> +	 * preemption or in the interrupt handler so barriers are needed
> +	 * before...
> +	 */
> +	smp_mb__before_atomic();
> +	atomic_set(&gpu->preempt_state, new);
> +	/* ... and after*/
> +	smp_mb__after_atomic();
> +}
> +
> +/* Write the most recent wptr for the given ring into the hardware */
> +static inline void update_wptr(struct msm_gpu *gpu, struct msm_ringbuffer *ring)
> +{
> +	unsigned long flags;
> +	uint32_t wptr;
> +
> +	spin_lock_irqsave(&ring->preempt_lock, flags);
> +
> +	if (ring->restore_wptr) {
> +		wptr = get_wptr(ring);
> +
> +		gpu_write(gpu, REG_A6XX_CP_RB_WPTR, wptr);
> +
> +		ring->restore_wptr = false;
> +	}
> +
> +	spin_unlock_irqrestore(&ring->preempt_lock, flags);
> +}
> +
> +/* Return the highest priority ringbuffer with something in it */
> +static struct msm_ringbuffer *get_next_ring(struct msm_gpu *gpu)
> +{
> +	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
> +	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
> +
> +	unsigned long flags;
> +	int i;
> +
> +	for (i = 0; i < gpu->nr_rings; i++) {
> +		bool empty;
> +		struct msm_ringbuffer *ring = gpu->rb[i];
> +
> +		spin_lock_irqsave(&ring->preempt_lock, flags);
> +		empty = (get_wptr(ring) == gpu->funcs->get_rptr(gpu, ring));
> +		if (!empty && ring == a6xx_gpu->cur_ring)
> +			empty = ring->memptrs->fence == a6xx_gpu->last_seqno[i];
> +		spin_unlock_irqrestore(&ring->preempt_lock, flags);
> +
> +		if (!empty)
> +			return ring;
> +	}
> +
> +	return NULL;
> +}
> +
> +static void a6xx_preempt_timer(struct timer_list *t)
> +{
> +	struct a6xx_gpu *a6xx_gpu = from_timer(a6xx_gpu, t, preempt_timer);
> +	struct msm_gpu *gpu = &a6xx_gpu->base.base;
> +	struct drm_device *dev = gpu->dev;
> +
> +	if (!try_preempt_state(a6xx_gpu, PREEMPT_TRIGGERED, PREEMPT_FAULTED))
> +		return;
> +
> +	dev_err(dev->dev, "%s: preemption timed out\n", gpu->name);
> +	kthread_queue_work(gpu->worker, &gpu->recover_work);
> +}
> +
> +void a6xx_preempt_irq(struct msm_gpu *gpu)
> +{
> +	uint32_t status;
> +	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
> +	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
> +	struct drm_device *dev = gpu->dev;
> +
> +	if (!try_preempt_state(a6xx_gpu, PREEMPT_TRIGGERED, PREEMPT_PENDING))
> +		return;
> +
> +	/* Delete the preemption watchdog timer */
> +	del_timer(&a6xx_gpu->preempt_timer);
> +
> +	/*
> +	 * The hardware should be setting the stop bit of CP_CONTEXT_SWITCH_CNTL
> +	 * to zero before firing the interrupt, but there is a non zero chance
> +	 * of a hardware condition or a software race that could set it again
> +	 * before we have a chance to finish. If that happens, log and go for
> +	 * recovery
> +	 */
> +	status = gpu_read(gpu, REG_A6XX_CP_CONTEXT_SWITCH_CNTL);
> +	if (unlikely(status & A6XX_CP_CONTEXT_SWITCH_CNTL_STOP)) {
> +		DRM_DEV_ERROR(&gpu->pdev->dev,
> +					  "!!!!!!!!!!!!!!!! preemption faulted !!!!!!!!!!!!!! irq\n");
> +		set_preempt_state(a6xx_gpu, PREEMPT_FAULTED);
> +		dev_err(dev->dev, "%s: Preemption failed to complete\n",
> +			gpu->name);
> +		kthread_queue_work(gpu->worker, &gpu->recover_work);
> +		return;
> +	}
> +
> +	a6xx_gpu->cur_ring = a6xx_gpu->next_ring;
> +	a6xx_gpu->next_ring = NULL;
> +
> +	set_preempt_state(a6xx_gpu, PREEMPT_FINISH);
> +
> +	update_wptr(gpu, a6xx_gpu->cur_ring);
> +
> +	set_preempt_state(a6xx_gpu, PREEMPT_NONE);
> +
> +	/*
> +	 * Retrigger preemption to avoid a deadlock that might occur when preemption
> +	 * is skipped due to it being already in flight when requested.
> +	 */
> +	a6xx_preempt_trigger(gpu);
> +}
> +
> +void a6xx_preempt_hw_init(struct msm_gpu *gpu)
> +{
> +	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
> +	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
> +	int i;
> +
> +	/* No preemption if we only have one ring */
> +	if (gpu->nr_rings == 1)
> +		return;
> +
> +	for (i = 0; i < gpu->nr_rings; i++) {
> +		struct a6xx_preempt_record *record_ptr =
> +			a6xx_gpu->preempt[i] + PREEMPT_OFFSET_PRIV_NON_SECURE;
> +		record_ptr->wptr = 0;
> +		record_ptr->rptr = 0;
> +		record_ptr->rptr_addr = shadowptr(a6xx_gpu, gpu->rb[i]);
> +		record_ptr->info = 0;
> +		record_ptr->data = 0;
> +		record_ptr->rbase = gpu->rb[i]->iova;
> +	}
> +
> +	/* Write a 0 to signal that we aren't switching pagetables */
> +	gpu_write64(gpu, REG_A6XX_CP_CONTEXT_SWITCH_SMMU_INFO, 0);
> +
> +	/* Enable the GMEM save/restore feature for preemption */
> +	gpu_write(gpu, REG_A6XX_RB_CONTEXT_SWITCH_GMEM_SAVE_RESTORE, 0x1);
> +
> +	/* Reset the preemption state */
> +	set_preempt_state(a6xx_gpu, PREEMPT_NONE);
> +
> +	spin_lock_init(&a6xx_gpu->eval_lock);
> +
> +	/* Always come up on rb 0 */
> +	a6xx_gpu->cur_ring = gpu->rb[0];
> +}
> +
> +void a6xx_preempt_trigger(struct msm_gpu *gpu)
> +{
> +	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
> +	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
> +	unsigned long flags;
> +	struct msm_ringbuffer *ring;
> +	unsigned int cntl;
> +
> +	if (gpu->nr_rings == 1)
> +		return;
> +
> +	/*
> +	 * Lock to make sure another thread attempting preemption doesn't skip it
> +	 * while we are still evaluating the next ring. This makes sure the other
> +	 * thread does start preemption if we abort it and avoids a soft lock.
> +	 */
> +	spin_lock_irqsave(&a6xx_gpu->eval_lock, flags);
> +
> +	/*
> +	 * Try to start preemption by moving from NONE to START. If
> +	 * unsuccessful, a preemption is already in flight
> +	 */
> +	if (!try_preempt_state(a6xx_gpu, PREEMPT_NONE, PREEMPT_START)) {
> +		spin_unlock_irqrestore(&a6xx_gpu->eval_lock, flags);
> +		return;
> +	}
> +
> +	cntl = A6XX_CP_CONTEXT_SWITCH_CNTL_LEVEL(a6xx_gpu->preempt_level);
> +
> +	if (a6xx_gpu->skip_save_restore)
> +		cntl |= A6XX_CP_CONTEXT_SWITCH_CNTL_SKIP_SAVE_RESTORE;
> +
> +	if (a6xx_gpu->uses_gmem)
> +		cntl |= A6XX_CP_CONTEXT_SWITCH_CNTL_USES_GMEM;
> +
> +	cntl |= A6XX_CP_CONTEXT_SWITCH_CNTL_STOP;
> +
> +	/* Get the next ring to preempt to */
> +	ring = get_next_ring(gpu);
> +
> +	/*
> +	 * If no ring is populated or the highest priority ring is the current
> +	 * one do nothing except to update the wptr to the latest and greatest
> +	 */
> +	if (!ring || (a6xx_gpu->cur_ring == ring)) {
> +		set_preempt_state(a6xx_gpu, PREEMPT_FINISH);
> +		update_wptr(gpu, a6xx_gpu->cur_ring);
> +		set_preempt_state(a6xx_gpu, PREEMPT_NONE);
> +		spin_unlock_irqrestore(&a6xx_gpu->eval_lock, flags);
> +		return;
> +	}
> +
> +	spin_unlock_irqrestore(&a6xx_gpu->eval_lock, flags);
> +
> +	spin_lock_irqsave(&ring->preempt_lock, flags);
> +
> +	struct a7xx_cp_smmu_info *smmu_info_ptr =
> +		a6xx_gpu->preempt[ring->id] + PREEMPT_OFFSET_SMMU_INFO;
> +	struct a6xx_preempt_record *record_ptr =
> +		a6xx_gpu->preempt[ring->id] + PREEMPT_OFFSET_PRIV_NON_SECURE;
> +	u64 ttbr0 = ring->memptrs->ttbr0;
> +	u32 context_idr = ring->memptrs->context_idr;
> +
> +	smmu_info_ptr->ttbr0 = ttbr0;
> +	smmu_info_ptr->context_idr = context_idr;
> +	record_ptr->wptr = get_wptr(ring);
> +
> +	/*
> +	 * The GPU will write the wptr we set above when we preempt. Reset
> +	 * restore_wptr to make sure that we don't write WPTR to the same
> +	 * thing twice. It's still possible subsequent submissions will update
> +	 * wptr again, in which case they will set the flag to true. This has
> +	 * to be protected by the lock for setting the flag and updating wptr
> +	 * to be atomic.
> +	 */
> +	ring->restore_wptr = false;
> +
> +	spin_unlock_irqrestore(&ring->preempt_lock, flags);
> +
> +	gpu_write64(gpu,
> +		REG_A6XX_CP_CONTEXT_SWITCH_SMMU_INFO,
> +		a6xx_gpu->preempt_iova[ring->id] + PREEMPT_OFFSET_SMMU_INFO);
> +
> +	gpu_write64(gpu,
> +		REG_A6XX_CP_CONTEXT_SWITCH_PRIV_NON_SECURE_RESTORE_ADDR,
> +		a6xx_gpu->preempt_iova[ring->id] + PREEMPT_OFFSET_PRIV_NON_SECURE);
> +
> +	a6xx_gpu->next_ring = ring;
> +
> +	/* Start a timer to catch a stuck preemption */
> +	mod_timer(&a6xx_gpu->preempt_timer, jiffies + msecs_to_jiffies(10000));
> +
> +	/* Set the preemption state to triggered */
> +	set_preempt_state(a6xx_gpu, PREEMPT_TRIGGERED);
> +
> +	/* Trigger the preemption */
> +	gpu_write(gpu, REG_A6XX_CP_CONTEXT_SWITCH_CNTL, cntl);
> +}
> +
> +static int preempt_init_ring(struct a6xx_gpu *a6xx_gpu,
> +		struct msm_ringbuffer *ring)
> +{
> +	struct adreno_gpu *adreno_gpu = &a6xx_gpu->base;
> +	struct msm_gpu *gpu = &adreno_gpu->base;
> +	struct drm_gem_object *bo = NULL;
> +	phys_addr_t ttbr;
> +	u64 iova = 0;
> +	void *ptr;
> +	int asid;
> +
> +	ptr = msm_gem_kernel_new(gpu->dev,
> +		PREEMPT_SIZE(adreno_gpu->info->preempt_record_size),
> +		MSM_BO_WC | MSM_BO_MAP_PRIV, gpu->aspace, &bo, &iova);
> +
> +	if (IS_ERR(ptr))
> +		return PTR_ERR(ptr);
> +
> +	memset(ptr, 0, PREEMPT_SIZE(adreno_gpu->info->preempt_record_size));
> +
> +	msm_gem_object_set_name(bo, "preempt_record");

I wish we could add ring id too. Anyway

Reviewed-by: Akhil P Oommen <quic_akhilpo@quicinc.com>

-Akhil

> +
> +	a6xx_gpu->preempt_bo[ring->id] = bo;
> +	a6xx_gpu->preempt_iova[ring->id] = iova;
> +	a6xx_gpu->preempt[ring->id] = ptr;
> +
> +	struct a7xx_cp_smmu_info *smmu_info_ptr = ptr + PREEMPT_OFFSET_SMMU_INFO;
> +	struct a6xx_preempt_record *record_ptr = ptr + PREEMPT_OFFSET_PRIV_NON_SECURE;
> +
> +	msm_iommu_pagetable_params(gpu->aspace->mmu, &ttbr, &asid);
> +
> +	smmu_info_ptr->magic = GEN7_CP_SMMU_INFO_MAGIC;
> +	smmu_info_ptr->ttbr0 = ttbr;
> +	smmu_info_ptr->asid = 0xdecafbad;
> +	smmu_info_ptr->context_idr = 0;
> +
> +	/* Set up the defaults on the preemption record */
> +	record_ptr->magic = A6XX_PREEMPT_RECORD_MAGIC;
> +	record_ptr->info = 0;
> +	record_ptr->data = 0;
> +	record_ptr->rptr = 0;
> +	record_ptr->wptr = 0;
> +	record_ptr->cntl = MSM_GPU_RB_CNTL_DEFAULT;
> +	record_ptr->rbase = ring->iova;
> +	record_ptr->counter = 0;
> +	record_ptr->bv_rptr_addr = rbmemptr(ring, bv_rptr);
> +
> +	return 0;
> +}
> +
> +void a6xx_preempt_fini(struct msm_gpu *gpu)
> +{
> +	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
> +	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
> +	int i;
> +
> +	for (i = 0; i < gpu->nr_rings; i++)
> +		msm_gem_kernel_put(a6xx_gpu->preempt_bo[i], gpu->aspace);
> +}
> +
> +void a6xx_preempt_init(struct msm_gpu *gpu)
> +{
> +	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
> +	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
> +	int i;
> +
> +	/* No preemption if we only have one ring */
> +	if (gpu->nr_rings <= 1)
> +		return;
> +
> +	for (i = 0; i < gpu->nr_rings; i++) {
> +		if (preempt_init_ring(a6xx_gpu, gpu->rb[i]))
> +			goto fail;
> +	}
> +
> +	/* TODO: make this configurable? */
> +	a6xx_gpu->preempt_level = 1;
> +	a6xx_gpu->uses_gmem = 1;
> +	a6xx_gpu->skip_save_restore = 1;
> +
> +	timer_setup(&a6xx_gpu->preempt_timer, a6xx_preempt_timer, 0);
> +
> +	return;
> +fail:
> +	/*
> +	 * On any failure our adventure is over. Clean up and
> +	 * set nr_rings to 1 to force preemption off
> +	 */
> +	a6xx_preempt_fini(gpu);
> +	gpu->nr_rings = 1;
> +
> +	DRM_DEV_ERROR(&gpu->pdev->dev,
> +				  "preemption init failed, disabling preemption\n");
> +
> +	return;
> +}
> diff --git a/drivers/gpu/drm/msm/msm_ringbuffer.h b/drivers/gpu/drm/msm/msm_ringbuffer.h
> index 174f83137a49..d1e49f701c81 100644
> --- a/drivers/gpu/drm/msm/msm_ringbuffer.h
> +++ b/drivers/gpu/drm/msm/msm_ringbuffer.h
> @@ -36,6 +36,7 @@ struct msm_rbmemptrs {
>  
>  	volatile struct msm_gpu_submit_stats stats[MSM_GPU_SUBMIT_STATS_COUNT];
>  	volatile u64 ttbr0;
> +	volatile u32 context_idr;
>  };
>  
>  struct msm_cp_state {
> @@ -101,6 +102,12 @@ struct msm_ringbuffer {
>  	 */
>  	spinlock_t preempt_lock;
>  
> +	/*
> +	 * Whether we skipped writing wptr and it needs to be updated in the
> +	 * future when the ring becomes current.
> +	 */
> +	bool restore_wptr;
> +
>  	/**
>  	 * cur_ctx_seqno:
>  	 *
> 
> -- 
> 2.46.0
>
diff mbox series

Patch

diff --git a/drivers/gpu/drm/msm/Makefile b/drivers/gpu/drm/msm/Makefile
index f5e2838c6a76..32e915109a59 100644
--- a/drivers/gpu/drm/msm/Makefile
+++ b/drivers/gpu/drm/msm/Makefile
@@ -23,6 +23,7 @@  adreno-y := \
 	adreno/a6xx_gpu.o \
 	adreno/a6xx_gmu.o \
 	adreno/a6xx_hfi.o \
+	adreno/a6xx_preempt.o \
 
 adreno-$(CONFIG_DEBUG_FS) += adreno/a5xx_debugfs.o \
 
diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index 6e065500b64d..355a3e210335 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -16,6 +16,84 @@ 
 
 #define GPU_PAS_ID 13
 
+/* IFPC & Preemption static powerup restore list */
+static const uint32_t a7xx_pwrup_reglist[] = {
+	REG_A6XX_UCHE_TRAP_BASE,
+	REG_A6XX_UCHE_TRAP_BASE + 1,
+	REG_A6XX_UCHE_WRITE_THRU_BASE,
+	REG_A6XX_UCHE_WRITE_THRU_BASE + 1,
+	REG_A6XX_UCHE_GMEM_RANGE_MIN,
+	REG_A6XX_UCHE_GMEM_RANGE_MIN + 1,
+	REG_A6XX_UCHE_GMEM_RANGE_MAX,
+	REG_A6XX_UCHE_GMEM_RANGE_MAX + 1,
+	REG_A6XX_UCHE_CACHE_WAYS,
+	REG_A6XX_UCHE_MODE_CNTL,
+	REG_A6XX_RB_NC_MODE_CNTL,
+	REG_A6XX_RB_CMP_DBG_ECO_CNTL,
+	REG_A7XX_GRAS_NC_MODE_CNTL,
+	REG_A6XX_RB_CONTEXT_SWITCH_GMEM_SAVE_RESTORE,
+	REG_A6XX_UCHE_GBIF_GX_CONFIG,
+	REG_A6XX_UCHE_CLIENT_PF,
+	REG_A6XX_TPL1_DBG_ECO_CNTL1,
+};
+
+static const uint32_t a7xx_ifpc_pwrup_reglist[] = {
+	REG_A6XX_TPL1_NC_MODE_CNTL,
+	REG_A6XX_SP_NC_MODE_CNTL,
+	REG_A6XX_CP_DBG_ECO_CNTL,
+	REG_A6XX_CP_PROTECT_CNTL,
+	REG_A6XX_CP_PROTECT(0),
+	REG_A6XX_CP_PROTECT(1),
+	REG_A6XX_CP_PROTECT(2),
+	REG_A6XX_CP_PROTECT(3),
+	REG_A6XX_CP_PROTECT(4),
+	REG_A6XX_CP_PROTECT(5),
+	REG_A6XX_CP_PROTECT(6),
+	REG_A6XX_CP_PROTECT(7),
+	REG_A6XX_CP_PROTECT(8),
+	REG_A6XX_CP_PROTECT(9),
+	REG_A6XX_CP_PROTECT(10),
+	REG_A6XX_CP_PROTECT(11),
+	REG_A6XX_CP_PROTECT(12),
+	REG_A6XX_CP_PROTECT(13),
+	REG_A6XX_CP_PROTECT(14),
+	REG_A6XX_CP_PROTECT(15),
+	REG_A6XX_CP_PROTECT(16),
+	REG_A6XX_CP_PROTECT(17),
+	REG_A6XX_CP_PROTECT(18),
+	REG_A6XX_CP_PROTECT(19),
+	REG_A6XX_CP_PROTECT(20),
+	REG_A6XX_CP_PROTECT(21),
+	REG_A6XX_CP_PROTECT(22),
+	REG_A6XX_CP_PROTECT(23),
+	REG_A6XX_CP_PROTECT(24),
+	REG_A6XX_CP_PROTECT(25),
+	REG_A6XX_CP_PROTECT(26),
+	REG_A6XX_CP_PROTECT(27),
+	REG_A6XX_CP_PROTECT(28),
+	REG_A6XX_CP_PROTECT(29),
+	REG_A6XX_CP_PROTECT(30),
+	REG_A6XX_CP_PROTECT(31),
+	REG_A6XX_CP_PROTECT(32),
+	REG_A6XX_CP_PROTECT(33),
+	REG_A6XX_CP_PROTECT(34),
+	REG_A6XX_CP_PROTECT(35),
+	REG_A6XX_CP_PROTECT(36),
+	REG_A6XX_CP_PROTECT(37),
+	REG_A6XX_CP_PROTECT(38),
+	REG_A6XX_CP_PROTECT(39),
+	REG_A6XX_CP_PROTECT(40),
+	REG_A6XX_CP_PROTECT(41),
+	REG_A6XX_CP_PROTECT(42),
+	REG_A6XX_CP_PROTECT(43),
+	REG_A6XX_CP_PROTECT(44),
+	REG_A6XX_CP_PROTECT(45),
+	REG_A6XX_CP_PROTECT(46),
+	REG_A6XX_CP_PROTECT(47),
+	REG_A6XX_CP_AHB_CNTL,
+};
+
+
 static inline bool _a6xx_check_idle(struct msm_gpu *gpu)
 {
 	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
@@ -68,6 +146,8 @@  static void update_shadow_rptr(struct msm_gpu *gpu, struct msm_ringbuffer *ring)
 
 static void a6xx_flush(struct msm_gpu *gpu, struct msm_ringbuffer *ring)
 {
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
 	uint32_t wptr;
 	unsigned long flags;
 
@@ -81,12 +161,17 @@  static void a6xx_flush(struct msm_gpu *gpu, struct msm_ringbuffer *ring)
 	/* Make sure to wrap wptr if we need to */
 	wptr = get_wptr(ring);
 
-	spin_unlock_irqrestore(&ring->preempt_lock, flags);
-
-	/* Make sure everything is posted before making a decision */
-	mb();
+	/* Update HW if this is the current ring and we are not in preempt*/
+	if (!a6xx_in_preempt(a6xx_gpu)) {
+		if (a6xx_gpu->cur_ring == ring)
+			gpu_write(gpu, REG_A6XX_CP_RB_WPTR, wptr);
+		else
+			ring->restore_wptr = true;
+	} else {
+		ring->restore_wptr = true;
+	}
 
-	gpu_write(gpu, REG_A6XX_CP_RB_WPTR, wptr);
+	spin_unlock_irqrestore(&ring->preempt_lock, flags);
 }
 
 static void get_stats_counter(struct msm_ringbuffer *ring, u32 counter,
@@ -138,12 +223,14 @@  static void a6xx_set_pagetable(struct a6xx_gpu *a6xx_gpu,
 
 	/*
 	 * Write the new TTBR0 to the memstore. This is good for debugging.
+	 * Needed for preemption
 	 */
-	OUT_PKT7(ring, CP_MEM_WRITE, 4);
+	OUT_PKT7(ring, CP_MEM_WRITE, 5);
 	OUT_RING(ring, CP_MEM_WRITE_0_ADDR_LO(lower_32_bits(memptr)));
 	OUT_RING(ring, CP_MEM_WRITE_1_ADDR_HI(upper_32_bits(memptr)));
 	OUT_RING(ring, lower_32_bits(ttbr));
-	OUT_RING(ring, (asid << 16) | upper_32_bits(ttbr));
+	OUT_RING(ring, upper_32_bits(ttbr));
+	OUT_RING(ring, ctx->seqno);
 
 	/*
 	 * Sync both threads after switching pagetables and enable BR only
@@ -268,6 +355,34 @@  static void a6xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 	a6xx_flush(gpu, ring);
 }
 
+static void a6xx_emit_set_pseudo_reg(struct msm_ringbuffer *ring,
+		struct a6xx_gpu *a6xx_gpu, struct msm_gpu_submitqueue *queue)
+{
+	OUT_PKT7(ring, CP_SET_PSEUDO_REG, 12);
+
+	OUT_RING(ring, SMMU_INFO);
+	/* don't save SMMU, we write the record from the kernel instead */
+	OUT_RING(ring, 0);
+	OUT_RING(ring, 0);
+
+	/* privileged and non secure buffer save */
+	OUT_RING(ring, NON_SECURE_SAVE_ADDR);
+	OUT_RING(ring, lower_32_bits(
+		a6xx_gpu->preempt_iova[ring->id] + PREEMPT_OFFSET_PRIV_NON_SECURE));
+	OUT_RING(ring, upper_32_bits(
+		a6xx_gpu->preempt_iova[ring->id] + PREEMPT_OFFSET_PRIV_NON_SECURE));
+
+	/* user context buffer save, seems to be unnused by fw */
+	OUT_RING(ring, NON_PRIV_SAVE_ADDR);
+	OUT_RING(ring, 0);
+	OUT_RING(ring, 0);
+
+	OUT_RING(ring, COUNTER);
+	/* seems OK to set to 0 to disable it */
+	OUT_RING(ring, 0);
+	OUT_RING(ring, 0);
+}
+
 static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 {
 	unsigned int index = submit->seqno % MSM_GPU_SUBMIT_STATS_COUNT;
@@ -285,6 +400,13 @@  static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 
 	a6xx_set_pagetable(a6xx_gpu, ring, submit->queue->ctx);
 
+	/*
+	 * If preemption is enabled, then set the pseudo register for the save
+	 * sequence
+	 */
+	if (gpu->nr_rings > 1)
+		a6xx_emit_set_pseudo_reg(ring, a6xx_gpu, submit->queue);
+
 	get_stats_counter(ring, REG_A7XX_RBBM_PERFCTR_CP(0),
 		rbmemptr_stats(ring, index, cpcycles_start));
 	get_stats_counter(ring, REG_A6XX_CP_ALWAYS_ON_COUNTER,
@@ -376,6 +498,8 @@  static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 	OUT_RING(ring, upper_32_bits(rbmemptr(ring, bv_fence)));
 	OUT_RING(ring, submit->seqno);
 
+	a6xx_gpu->last_seqno[ring->id] = submit->seqno;
+
 	/* write the ringbuffer timestamp */
 	OUT_PKT7(ring, CP_EVENT_WRITE, 4);
 	OUT_RING(ring, CACHE_CLEAN | CP_EVENT_WRITE_0_IRQ | BIT(27));
@@ -389,10 +513,32 @@  static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 	OUT_PKT7(ring, CP_SET_MARKER, 1);
 	OUT_RING(ring, 0x100); /* IFPC enable */
 
+	/* If preemption is enabled */
+	if (gpu->nr_rings > 1) {
+		/* Yield the floor on command completion */
+		OUT_PKT7(ring, CP_CONTEXT_SWITCH_YIELD, 4);
+
+		/*
+		 * If dword[2:1] are non zero, they specify an address for
+		 * the CP to write the value of dword[3] to on preemption
+		 * complete. Write 0 to skip the write
+		 */
+		OUT_RING(ring, 0x00);
+		OUT_RING(ring, 0x00);
+		/* Data value - not used if the address above is 0 */
+		OUT_RING(ring, 0x01);
+		/* generate interrupt on preemption completion */
+		OUT_RING(ring, 0x00);
+	}
+
+
 	trace_msm_gpu_submit_flush(submit,
 		gpu_read64(gpu, REG_A6XX_CP_ALWAYS_ON_COUNTER));
 
 	a6xx_flush(gpu, ring);
+
+	/* Check to see if we need to start preemption */
+	a6xx_preempt_trigger(gpu);
 }
 
 static void a6xx_set_hwcg(struct msm_gpu *gpu, bool state)
@@ -588,6 +734,89 @@  static void a6xx_set_ubwc_config(struct msm_gpu *gpu)
 		  adreno_gpu->ubwc_config.min_acc_len << 23 | hbb_lo << 21);
 }
 
+static void a7xx_patch_pwrup_reglist(struct msm_gpu *gpu)
+{
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
+	struct adreno_reglist_list reglist[2];
+	void *ptr = a6xx_gpu->pwrup_reglist_ptr;
+	struct cpu_gpu_lock *lock = ptr;
+	u32 *dest = (u32 *)&lock->regs[0];
+	int i, j;
+
+	lock->gpu_req = lock->cpu_req = lock->turn = 0;
+	lock->ifpc_list_len = ARRAY_SIZE(a7xx_ifpc_pwrup_reglist);
+	lock->preemption_list_len = ARRAY_SIZE(a7xx_pwrup_reglist);
+
+	/* Static IFPC-only registers */
+	reglist[0].regs = a7xx_ifpc_pwrup_reglist;
+	reglist[0].count = ARRAY_SIZE(a7xx_ifpc_pwrup_reglist);
+	lock->ifpc_list_len = reglist[0].count;
+
+	/* Static IFPC + preemption registers */
+	reglist[1].regs = a7xx_pwrup_reglist;
+	reglist[1].count = ARRAY_SIZE(a7xx_pwrup_reglist);
+	lock->preemption_list_len = reglist[1].count;
+
+	/*
+	 * For each entry in each of the lists, write the offset and the current
+	 * register value into the GPU buffer
+	 */
+	for (i = 0; i < 2; i++) {
+		const u32 *r = reglist[i].regs;
+
+		for (j = 0; j < reglist[i].count; j++) {
+			*dest++ = r[j];
+			*dest++ = gpu_read(gpu, r[j]);
+		}
+	}
+
+	/*
+	 * The overall register list is composed of
+	 * 1. Static IFPC-only registers
+	 * 2. Static IFPC + preemption registers
+	 * 3. Dynamic IFPC + preemption registers (ex: perfcounter selects)
+	 *
+	 * The first two lists are static. Size of these lists are stored as
+	 * number of pairs in ifpc_list_len and preemption_list_len
+	 * respectively. With concurrent binning, Some of the perfcounter
+	 * registers being virtualized, CP needs to know the pipe id to program
+	 * the aperture inorder to restore the same. Thus, third list is a
+	 * dynamic list with triplets as
+	 * (<aperture, shifted 12 bits> <address> <data>), and the length is
+	 * stored as number for triplets in dynamic_list_len.
+	 */
+	lock->dynamic_list_len = 0;
+}
+
+static int a7xx_preempt_start(struct msm_gpu *gpu)
+{
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
+	struct msm_ringbuffer *ring = gpu->rb[0];
+
+	if (gpu->nr_rings <= 1)
+		return 0;
+
+	/* Turn CP protection off */
+	OUT_PKT7(ring, CP_SET_PROTECTED_MODE, 1);
+	OUT_RING(ring, 0);
+
+	a6xx_emit_set_pseudo_reg(ring, a6xx_gpu, NULL);
+
+	/* Yield the floor on command completion */
+	OUT_PKT7(ring, CP_CONTEXT_SWITCH_YIELD, 4);
+	OUT_RING(ring, 0x00);
+	OUT_RING(ring, 0x00);
+	OUT_RING(ring, 0x00);
+	/* Generate interrupt on preemption completion */
+	OUT_RING(ring, 0x00);
+
+	a6xx_flush(gpu, ring);
+
+	return a6xx_idle(gpu, ring) ? 0 : -EINVAL;
+}
+
 static int a6xx_cp_init(struct msm_gpu *gpu)
 {
 	struct msm_ringbuffer *ring = gpu->rb[0];
@@ -619,6 +848,8 @@  static int a6xx_cp_init(struct msm_gpu *gpu)
 
 static int a7xx_cp_init(struct msm_gpu *gpu)
 {
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
 	struct msm_ringbuffer *ring = gpu->rb[0];
 	u32 mask;
 
@@ -656,11 +887,11 @@  static int a7xx_cp_init(struct msm_gpu *gpu)
 
 	/* *Don't* send a power up reg list for concurrent binning (TODO) */
 	/* Lo address */
-	OUT_RING(ring, 0x00000000);
+	OUT_RING(ring, lower_32_bits(a6xx_gpu->pwrup_reglist_iova));
 	/* Hi address */
-	OUT_RING(ring, 0x00000000);
+	OUT_RING(ring, upper_32_bits(a6xx_gpu->pwrup_reglist_iova));
 	/* BIT(31) set => read the regs from the list */
-	OUT_RING(ring, 0x00000000);
+	OUT_RING(ring, BIT(31));
 
 	a6xx_flush(gpu, ring);
 	return a6xx_idle(gpu, ring) ? 0 : -EINVAL;
@@ -784,6 +1015,16 @@  static int a6xx_ucode_load(struct msm_gpu *gpu)
 		msm_gem_object_set_name(a6xx_gpu->shadow_bo, "shadow");
 	}
 
+	a6xx_gpu->pwrup_reglist_ptr = msm_gem_kernel_new(gpu->dev, PAGE_SIZE,
+							 MSM_BO_WC  | MSM_BO_MAP_PRIV,
+							 gpu->aspace, &a6xx_gpu->pwrup_reglist_bo,
+							 &a6xx_gpu->pwrup_reglist_iova);
+
+	if (IS_ERR(a6xx_gpu->pwrup_reglist_ptr))
+		return PTR_ERR(a6xx_gpu->pwrup_reglist_ptr);
+
+	msm_gem_object_set_name(a6xx_gpu->pwrup_reglist_bo, "pwrup_reglist");
+
 	return 0;
 }
 
@@ -1128,6 +1369,8 @@  static int hw_init(struct msm_gpu *gpu)
 	if (a6xx_gpu->shadow_bo) {
 		gpu_write64(gpu, REG_A6XX_CP_RB_RPTR_ADDR,
 			shadowptr(a6xx_gpu, gpu->rb[0]));
+		for (unsigned int i = 0; i < gpu->nr_rings; i++)
+			a6xx_gpu->shadow[i] = 0;
 	}
 
 	/* ..which means "always" on A7xx, also for BV shadow */
@@ -1136,6 +1379,8 @@  static int hw_init(struct msm_gpu *gpu)
 			    rbmemptr(gpu->rb[0], bv_rptr));
 	}
 
+	a6xx_preempt_hw_init(gpu);
+
 	/* Always come up on rb 0 */
 	a6xx_gpu->cur_ring = gpu->rb[0];
 
@@ -1145,6 +1390,11 @@  static int hw_init(struct msm_gpu *gpu)
 	/* Enable the SQE_to start the CP engine */
 	gpu_write(gpu, REG_A6XX_CP_SQE_CNTL, 1);
 
+	if (adreno_is_a7xx(adreno_gpu) && !a6xx_gpu->pwrup_reglist_emitted) {
+		a7xx_patch_pwrup_reglist(gpu);
+		a6xx_gpu->pwrup_reglist_emitted = true;
+	}
+
 	ret = adreno_is_a7xx(adreno_gpu) ? a7xx_cp_init(gpu) : a6xx_cp_init(gpu);
 	if (ret)
 		goto out;
@@ -1182,6 +1432,10 @@  static int hw_init(struct msm_gpu *gpu)
 out:
 	if (adreno_has_gmu_wrapper(adreno_gpu))
 		return ret;
+
+	/* Last step - yield the ringbuffer */
+	a7xx_preempt_start(gpu);
+
 	/*
 	 * Tell the GMU that we are done touching the GPU and it can start power
 	 * management
@@ -1559,8 +1813,13 @@  static irqreturn_t a6xx_irq(struct msm_gpu *gpu)
 	if (status & A6XX_RBBM_INT_0_MASK_SWFUSEVIOLATION)
 		a7xx_sw_fuse_violation_irq(gpu);
 
-	if (status & A6XX_RBBM_INT_0_MASK_CP_CACHE_FLUSH_TS)
+	if (status & A6XX_RBBM_INT_0_MASK_CP_CACHE_FLUSH_TS) {
 		msm_gpu_retire(gpu);
+		a6xx_preempt_trigger(gpu);
+	}
+
+	if (status & A6XX_RBBM_INT_0_MASK_CP_SW)
+		a6xx_preempt_irq(gpu);
 
 	return IRQ_HANDLED;
 }
@@ -2333,6 +2592,8 @@  struct msm_gpu *a6xx_gpu_init(struct drm_device *dev)
 				a6xx_fault_handler);
 
 	a6xx_calc_ubwc_config(adreno_gpu);
+	/* Set up the preemption specific bits and pieces for each ringbuffer */
+	a6xx_preempt_init(gpu);
 
 	return gpu;
 }
diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
index e3e5c53ae8af..7fc994121676 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
@@ -12,6 +12,31 @@ 
 
 extern bool hang_debug;
 
+struct cpu_gpu_lock {
+	uint32_t gpu_req;
+	uint32_t cpu_req;
+	uint32_t turn;
+	union {
+		struct {
+			uint16_t list_length;
+			uint16_t list_offset;
+		};
+		struct {
+			uint8_t ifpc_list_len;
+			uint8_t preemption_list_len;
+			uint16_t dynamic_list_len;
+		};
+	};
+	uint64_t regs[62];
+};
+
+struct adreno_reglist_list {
+	/** @reg: List of register **/
+	const u32 *regs;
+	/** @count: Number of registers in the list **/
+	u32 count;
+};
+
 /**
  * struct a6xx_info - a6xx specific information from device table
  *
@@ -31,6 +56,20 @@  struct a6xx_gpu {
 	uint64_t sqe_iova;
 
 	struct msm_ringbuffer *cur_ring;
+	struct msm_ringbuffer *next_ring;
+
+	struct drm_gem_object *preempt_bo[MSM_GPU_MAX_RINGS];
+	void *preempt[MSM_GPU_MAX_RINGS];
+	uint64_t preempt_iova[MSM_GPU_MAX_RINGS];
+	uint32_t last_seqno[MSM_GPU_MAX_RINGS];
+
+	atomic_t preempt_state;
+	spinlock_t eval_lock;
+	struct timer_list preempt_timer;
+
+	unsigned int preempt_level;
+	bool uses_gmem;
+	bool skip_save_restore;
 
 	struct a6xx_gmu gmu;
 
@@ -38,6 +77,11 @@  struct a6xx_gpu {
 	uint64_t shadow_iova;
 	uint32_t *shadow;
 
+	struct drm_gem_object *pwrup_reglist_bo;
+	void *pwrup_reglist_ptr;
+	uint64_t pwrup_reglist_iova;
+	bool pwrup_reglist_emitted;
+
 	bool has_whereami;
 
 	void __iomem *llc_mmio;
@@ -49,6 +93,102 @@  struct a6xx_gpu {
 
 #define to_a6xx_gpu(x) container_of(x, struct a6xx_gpu, base)
 
+/*
+ * In order to do lockless preemption we use a simple state machine to progress
+ * through the process.
+ *
+ * PREEMPT_NONE - no preemption in progress.  Next state START.
+ * PREEMPT_START - The trigger is evaluating if preemption is possible. Next
+ * states: TRIGGERED, NONE
+ * PREEMPT_FINISH - An intermediate state before moving back to NONE. Next
+ * state: NONE.
+ * PREEMPT_TRIGGERED: A preemption has been executed on the hardware. Next
+ * states: FAULTED, PENDING
+ * PREEMPT_FAULTED: A preemption timed out (never completed). This will trigger
+ * recovery.  Next state: N/A
+ * PREEMPT_PENDING: Preemption complete interrupt fired - the callback is
+ * checking the success of the operation. Next state: FAULTED, NONE.
+ */
+
+enum a6xx_preempt_state {
+	PREEMPT_NONE = 0,
+	PREEMPT_START,
+	PREEMPT_FINISH,
+	PREEMPT_TRIGGERED,
+	PREEMPT_FAULTED,
+	PREEMPT_PENDING,
+};
+
+/*
+ * struct a6xx_preempt_record is a shared buffer between the microcode and the
+ * CPU to store the state for preemption. The record itself is much larger
+ * (2112k) but most of that is used by the CP for storage.
+ *
+ * There is a preemption record assigned per ringbuffer. When the CPU triggers a
+ * preemption, it fills out the record with the useful information (wptr, ring
+ * base, etc) and the microcode uses that information to set up the CP following
+ * the preemption.  When a ring is switched out, the CP will save the ringbuffer
+ * state back to the record. In this way, once the records are properly set up
+ * the CPU can quickly switch back and forth between ringbuffers by only
+ * updating a few registers (often only the wptr).
+ *
+ * These are the CPU aware registers in the record:
+ * @magic: Must always be 0xAE399D6EUL
+ * @info: Type of the record - written 0 by the CPU, updated by the CP
+ * @errno: preemption error record
+ * @data: Data field in YIELD and SET_MARKER packets, Written and used by CP
+ * @cntl: Value of RB_CNTL written by CPU, save/restored by CP
+ * @rptr: Value of RB_RPTR written by CPU, save/restored by CP
+ * @wptr: Value of RB_WPTR written by CPU, save/restored by CP
+ * @_pad: Reserved/padding
+ * @rptr_addr: Value of RB_RPTR_ADDR_LO|HI written by CPU, save/restored by CP
+ * @rbase: Value of RB_BASE written by CPU, save/restored by CP
+ * @counter: GPU address of the storage area for the preemption counters
+ * @bv_rptr_addr: Value of BV_RB_RPTR_ADDR_LO|HI written by CPU, save/restored by CP
+ */
+struct a6xx_preempt_record {
+	u32 magic;
+	u32 info;
+	u32 errno;
+	u32 data;
+	u32 cntl;
+	u32 rptr;
+	u32 wptr;
+	u32 _pad;
+	u64 rptr_addr;
+	u64 rbase;
+	u64 counter;
+	u64 bv_rptr_addr;
+};
+
+#define A6XX_PREEMPT_RECORD_MAGIC 0xAE399D6EUL
+
+#define PREEMPT_RECORD_SIZE_FALLBACK(size) \
+	((size) == 0 ? 4192 * SZ_1K : (size))
+
+#define PREEMPT_OFFSET_SMMU_INFO 0
+#define PREEMPT_OFFSET_PRIV_NON_SECURE (PREEMPT_OFFSET_SMMU_INFO + 4096)
+#define PREEMPT_SIZE(size) \
+	(PREEMPT_OFFSET_PRIV_NON_SECURE + PREEMPT_RECORD_SIZE_FALLBACK(size))
+
+/*
+ * The preemption counter block is a storage area for the value of the
+ * preemption counters that are saved immediately before context switch. We
+ * append it on to the end of the allocation for the preemption record.
+ */
+#define A6XX_PREEMPT_COUNTER_SIZE (16 * 4)
+
+struct a7xx_cp_smmu_info {
+	u32 magic;
+	u32 _pad4;
+	u64 ttbr0;
+	u32 asid;
+	u32 context_idr;
+	u32 context_bank;
+};
+
+#define GEN7_CP_SMMU_INFO_MAGIC 0x241350d5UL
+
 /*
  * Given a register and a count, return a value to program into
  * REG_CP_PROTECT_REG(n) - this will block both reads and writes for
@@ -106,6 +246,34 @@  int a6xx_gmu_init(struct a6xx_gpu *a6xx_gpu, struct device_node *node);
 int a6xx_gmu_wrapper_init(struct a6xx_gpu *a6xx_gpu, struct device_node *node);
 void a6xx_gmu_remove(struct a6xx_gpu *a6xx_gpu);
 
+void a6xx_preempt_init(struct msm_gpu *gpu);
+void a6xx_preempt_hw_init(struct msm_gpu *gpu);
+void a6xx_preempt_trigger(struct msm_gpu *gpu);
+void a6xx_preempt_irq(struct msm_gpu *gpu);
+void a6xx_preempt_fini(struct msm_gpu *gpu);
+int a6xx_preempt_submitqueue_setup(struct msm_gpu *gpu,
+		struct msm_gpu_submitqueue *queue);
+void a6xx_preempt_submitqueue_close(struct msm_gpu *gpu,
+		struct msm_gpu_submitqueue *queue);
+
+/* Return true if we are in a preempt state */
+static inline bool a6xx_in_preempt(struct a6xx_gpu *a6xx_gpu)
+{
+	/*
+	 * Make sure the read to preempt_state is ordered with respect to reads
+	 * of other variables before ...
+	 */
+	smp_rmb();
+
+	int preempt_state = atomic_read(&a6xx_gpu->preempt_state);
+
+	/* ... and after. */
+	smp_rmb();
+
+	return !(preempt_state == PREEMPT_NONE ||
+			preempt_state == PREEMPT_FINISH);
+}
+
 void a6xx_gmu_set_freq(struct msm_gpu *gpu, struct dev_pm_opp *opp,
 		       bool suspended);
 unsigned long a6xx_gmu_get_freq(struct msm_gpu *gpu);
diff --git a/drivers/gpu/drm/msm/adreno/a6xx_preempt.c b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
new file mode 100644
index 000000000000..aa4bad394f9e
--- /dev/null
+++ b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
@@ -0,0 +1,377 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2018, The Linux Foundation. All rights reserved. */
+/* Copyright (c) 2023 Collabora, Ltd. */
+/* Copyright (c) 2024 Valve Corporation */
+
+#include "msm_gem.h"
+#include "a6xx_gpu.h"
+#include "a6xx_gmu.xml.h"
+#include "msm_mmu.h"
+
+/*
+ * Try to transition the preemption state from old to new. Return
+ * true on success or false if the original state wasn't 'old'
+ */
+static inline bool try_preempt_state(struct a6xx_gpu *a6xx_gpu,
+		enum a6xx_preempt_state old, enum a6xx_preempt_state new)
+{
+	enum a6xx_preempt_state cur = atomic_cmpxchg(&a6xx_gpu->preempt_state,
+		old, new);
+
+	return (cur == old);
+}
+
+/*
+ * Force the preemption state to the specified state.  This is used in cases
+ * where the current state is known and won't change
+ */
+static inline void set_preempt_state(struct a6xx_gpu *gpu,
+		enum a6xx_preempt_state new)
+{
+	/*
+	 * preempt_state may be read by other cores trying to trigger a
+	 * preemption or in the interrupt handler so barriers are needed
+	 * before...
+	 */
+	smp_mb__before_atomic();
+	atomic_set(&gpu->preempt_state, new);
+	/* ... and after*/
+	smp_mb__after_atomic();
+}
+
+/* Write the most recent wptr for the given ring into the hardware */
+static inline void update_wptr(struct msm_gpu *gpu, struct msm_ringbuffer *ring)
+{
+	unsigned long flags;
+	uint32_t wptr;
+
+	spin_lock_irqsave(&ring->preempt_lock, flags);
+
+	if (ring->restore_wptr) {
+		wptr = get_wptr(ring);
+
+		gpu_write(gpu, REG_A6XX_CP_RB_WPTR, wptr);
+
+		ring->restore_wptr = false;
+	}
+
+	spin_unlock_irqrestore(&ring->preempt_lock, flags);
+}
+
+/* Return the highest priority ringbuffer with something in it */
+static struct msm_ringbuffer *get_next_ring(struct msm_gpu *gpu)
+{
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
+
+	unsigned long flags;
+	int i;
+
+	for (i = 0; i < gpu->nr_rings; i++) {
+		bool empty;
+		struct msm_ringbuffer *ring = gpu->rb[i];
+
+		spin_lock_irqsave(&ring->preempt_lock, flags);
+		empty = (get_wptr(ring) == gpu->funcs->get_rptr(gpu, ring));
+		if (!empty && ring == a6xx_gpu->cur_ring)
+			empty = ring->memptrs->fence == a6xx_gpu->last_seqno[i];
+		spin_unlock_irqrestore(&ring->preempt_lock, flags);
+
+		if (!empty)
+			return ring;
+	}
+
+	return NULL;
+}
+
+static void a6xx_preempt_timer(struct timer_list *t)
+{
+	struct a6xx_gpu *a6xx_gpu = from_timer(a6xx_gpu, t, preempt_timer);
+	struct msm_gpu *gpu = &a6xx_gpu->base.base;
+	struct drm_device *dev = gpu->dev;
+
+	if (!try_preempt_state(a6xx_gpu, PREEMPT_TRIGGERED, PREEMPT_FAULTED))
+		return;
+
+	dev_err(dev->dev, "%s: preemption timed out\n", gpu->name);
+	kthread_queue_work(gpu->worker, &gpu->recover_work);
+}
+
+void a6xx_preempt_irq(struct msm_gpu *gpu)
+{
+	uint32_t status;
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
+	struct drm_device *dev = gpu->dev;
+
+	if (!try_preempt_state(a6xx_gpu, PREEMPT_TRIGGERED, PREEMPT_PENDING))
+		return;
+
+	/* Delete the preemption watchdog timer */
+	del_timer(&a6xx_gpu->preempt_timer);
+
+	/*
+	 * The hardware should be setting the stop bit of CP_CONTEXT_SWITCH_CNTL
+	 * to zero before firing the interrupt, but there is a non zero chance
+	 * of a hardware condition or a software race that could set it again
+	 * before we have a chance to finish. If that happens, log and go for
+	 * recovery
+	 */
+	status = gpu_read(gpu, REG_A6XX_CP_CONTEXT_SWITCH_CNTL);
+	if (unlikely(status & A6XX_CP_CONTEXT_SWITCH_CNTL_STOP)) {
+		DRM_DEV_ERROR(&gpu->pdev->dev,
+					  "!!!!!!!!!!!!!!!! preemption faulted !!!!!!!!!!!!!! irq\n");
+		set_preempt_state(a6xx_gpu, PREEMPT_FAULTED);
+		dev_err(dev->dev, "%s: Preemption failed to complete\n",
+			gpu->name);
+		kthread_queue_work(gpu->worker, &gpu->recover_work);
+		return;
+	}
+
+	a6xx_gpu->cur_ring = a6xx_gpu->next_ring;
+	a6xx_gpu->next_ring = NULL;
+
+	set_preempt_state(a6xx_gpu, PREEMPT_FINISH);
+
+	update_wptr(gpu, a6xx_gpu->cur_ring);
+
+	set_preempt_state(a6xx_gpu, PREEMPT_NONE);
+
+	/*
+	 * Retrigger preemption to avoid a deadlock that might occur when preemption
+	 * is skipped due to it being already in flight when requested.
+	 */
+	a6xx_preempt_trigger(gpu);
+}
+
+void a6xx_preempt_hw_init(struct msm_gpu *gpu)
+{
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
+	int i;
+
+	/* No preemption if we only have one ring */
+	if (gpu->nr_rings == 1)
+		return;
+
+	for (i = 0; i < gpu->nr_rings; i++) {
+		struct a6xx_preempt_record *record_ptr =
+			a6xx_gpu->preempt[i] + PREEMPT_OFFSET_PRIV_NON_SECURE;
+		record_ptr->wptr = 0;
+		record_ptr->rptr = 0;
+		record_ptr->rptr_addr = shadowptr(a6xx_gpu, gpu->rb[i]);
+		record_ptr->info = 0;
+		record_ptr->data = 0;
+		record_ptr->rbase = gpu->rb[i]->iova;
+	}
+
+	/* Write a 0 to signal that we aren't switching pagetables */
+	gpu_write64(gpu, REG_A6XX_CP_CONTEXT_SWITCH_SMMU_INFO, 0);
+
+	/* Enable the GMEM save/restore feature for preemption */
+	gpu_write(gpu, REG_A6XX_RB_CONTEXT_SWITCH_GMEM_SAVE_RESTORE, 0x1);
+
+	/* Reset the preemption state */
+	set_preempt_state(a6xx_gpu, PREEMPT_NONE);
+
+	spin_lock_init(&a6xx_gpu->eval_lock);
+
+	/* Always come up on rb 0 */
+	a6xx_gpu->cur_ring = gpu->rb[0];
+}
+
+void a6xx_preempt_trigger(struct msm_gpu *gpu)
+{
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
+	unsigned long flags;
+	struct msm_ringbuffer *ring;
+	unsigned int cntl;
+
+	if (gpu->nr_rings == 1)
+		return;
+
+	/*
+	 * Lock to make sure another thread attempting preemption doesn't skip it
+	 * while we are still evaluating the next ring. This makes sure the other
+	 * thread does start preemption if we abort it and avoids a soft lock.
+	 */
+	spin_lock_irqsave(&a6xx_gpu->eval_lock, flags);
+
+	/*
+	 * Try to start preemption by moving from NONE to START. If
+	 * unsuccessful, a preemption is already in flight
+	 */
+	if (!try_preempt_state(a6xx_gpu, PREEMPT_NONE, PREEMPT_START)) {
+		spin_unlock_irqrestore(&a6xx_gpu->eval_lock, flags);
+		return;
+	}
+
+	cntl = A6XX_CP_CONTEXT_SWITCH_CNTL_LEVEL(a6xx_gpu->preempt_level);
+
+	if (a6xx_gpu->skip_save_restore)
+		cntl |= A6XX_CP_CONTEXT_SWITCH_CNTL_SKIP_SAVE_RESTORE;
+
+	if (a6xx_gpu->uses_gmem)
+		cntl |= A6XX_CP_CONTEXT_SWITCH_CNTL_USES_GMEM;
+
+	cntl |= A6XX_CP_CONTEXT_SWITCH_CNTL_STOP;
+
+	/* Get the next ring to preempt to */
+	ring = get_next_ring(gpu);
+
+	/*
+	 * If no ring is populated or the highest priority ring is the current
+	 * one do nothing except to update the wptr to the latest and greatest
+	 */
+	if (!ring || (a6xx_gpu->cur_ring == ring)) {
+		set_preempt_state(a6xx_gpu, PREEMPT_FINISH);
+		update_wptr(gpu, a6xx_gpu->cur_ring);
+		set_preempt_state(a6xx_gpu, PREEMPT_NONE);
+		spin_unlock_irqrestore(&a6xx_gpu->eval_lock, flags);
+		return;
+	}
+
+	spin_unlock_irqrestore(&a6xx_gpu->eval_lock, flags);
+
+	spin_lock_irqsave(&ring->preempt_lock, flags);
+
+	struct a7xx_cp_smmu_info *smmu_info_ptr =
+		a6xx_gpu->preempt[ring->id] + PREEMPT_OFFSET_SMMU_INFO;
+	struct a6xx_preempt_record *record_ptr =
+		a6xx_gpu->preempt[ring->id] + PREEMPT_OFFSET_PRIV_NON_SECURE;
+	u64 ttbr0 = ring->memptrs->ttbr0;
+	u32 context_idr = ring->memptrs->context_idr;
+
+	smmu_info_ptr->ttbr0 = ttbr0;
+	smmu_info_ptr->context_idr = context_idr;
+	record_ptr->wptr = get_wptr(ring);
+
+	/*
+	 * The GPU will write the wptr we set above when we preempt. Reset
+	 * restore_wptr to make sure that we don't write WPTR to the same
+	 * thing twice. It's still possible subsequent submissions will update
+	 * wptr again, in which case they will set the flag to true. This has
+	 * to be protected by the lock for setting the flag and updating wptr
+	 * to be atomic.
+	 */
+	ring->restore_wptr = false;
+
+	spin_unlock_irqrestore(&ring->preempt_lock, flags);
+
+	gpu_write64(gpu,
+		REG_A6XX_CP_CONTEXT_SWITCH_SMMU_INFO,
+		a6xx_gpu->preempt_iova[ring->id] + PREEMPT_OFFSET_SMMU_INFO);
+
+	gpu_write64(gpu,
+		REG_A6XX_CP_CONTEXT_SWITCH_PRIV_NON_SECURE_RESTORE_ADDR,
+		a6xx_gpu->preempt_iova[ring->id] + PREEMPT_OFFSET_PRIV_NON_SECURE);
+
+	a6xx_gpu->next_ring = ring;
+
+	/* Start a timer to catch a stuck preemption */
+	mod_timer(&a6xx_gpu->preempt_timer, jiffies + msecs_to_jiffies(10000));
+
+	/* Set the preemption state to triggered */
+	set_preempt_state(a6xx_gpu, PREEMPT_TRIGGERED);
+
+	/* Trigger the preemption */
+	gpu_write(gpu, REG_A6XX_CP_CONTEXT_SWITCH_CNTL, cntl);
+}
+
+static int preempt_init_ring(struct a6xx_gpu *a6xx_gpu,
+		struct msm_ringbuffer *ring)
+{
+	struct adreno_gpu *adreno_gpu = &a6xx_gpu->base;
+	struct msm_gpu *gpu = &adreno_gpu->base;
+	struct drm_gem_object *bo = NULL;
+	phys_addr_t ttbr;
+	u64 iova = 0;
+	void *ptr;
+	int asid;
+
+	ptr = msm_gem_kernel_new(gpu->dev,
+		PREEMPT_SIZE(adreno_gpu->info->preempt_record_size),
+		MSM_BO_WC | MSM_BO_MAP_PRIV, gpu->aspace, &bo, &iova);
+
+	if (IS_ERR(ptr))
+		return PTR_ERR(ptr);
+
+	memset(ptr, 0, PREEMPT_SIZE(adreno_gpu->info->preempt_record_size));
+
+	msm_gem_object_set_name(bo, "preempt_record");
+
+	a6xx_gpu->preempt_bo[ring->id] = bo;
+	a6xx_gpu->preempt_iova[ring->id] = iova;
+	a6xx_gpu->preempt[ring->id] = ptr;
+
+	struct a7xx_cp_smmu_info *smmu_info_ptr = ptr + PREEMPT_OFFSET_SMMU_INFO;
+	struct a6xx_preempt_record *record_ptr = ptr + PREEMPT_OFFSET_PRIV_NON_SECURE;
+
+	msm_iommu_pagetable_params(gpu->aspace->mmu, &ttbr, &asid);
+
+	smmu_info_ptr->magic = GEN7_CP_SMMU_INFO_MAGIC;
+	smmu_info_ptr->ttbr0 = ttbr;
+	smmu_info_ptr->asid = 0xdecafbad;
+	smmu_info_ptr->context_idr = 0;
+
+	/* Set up the defaults on the preemption record */
+	record_ptr->magic = A6XX_PREEMPT_RECORD_MAGIC;
+	record_ptr->info = 0;
+	record_ptr->data = 0;
+	record_ptr->rptr = 0;
+	record_ptr->wptr = 0;
+	record_ptr->cntl = MSM_GPU_RB_CNTL_DEFAULT;
+	record_ptr->rbase = ring->iova;
+	record_ptr->counter = 0;
+	record_ptr->bv_rptr_addr = rbmemptr(ring, bv_rptr);
+
+	return 0;
+}
+
+void a6xx_preempt_fini(struct msm_gpu *gpu)
+{
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
+	int i;
+
+	for (i = 0; i < gpu->nr_rings; i++)
+		msm_gem_kernel_put(a6xx_gpu->preempt_bo[i], gpu->aspace);
+}
+
+void a6xx_preempt_init(struct msm_gpu *gpu)
+{
+	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
+	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
+	int i;
+
+	/* No preemption if we only have one ring */
+	if (gpu->nr_rings <= 1)
+		return;
+
+	for (i = 0; i < gpu->nr_rings; i++) {
+		if (preempt_init_ring(a6xx_gpu, gpu->rb[i]))
+			goto fail;
+	}
+
+	/* TODO: make this configurable? */
+	a6xx_gpu->preempt_level = 1;
+	a6xx_gpu->uses_gmem = 1;
+	a6xx_gpu->skip_save_restore = 1;
+
+	timer_setup(&a6xx_gpu->preempt_timer, a6xx_preempt_timer, 0);
+
+	return;
+fail:
+	/*
+	 * On any failure our adventure is over. Clean up and
+	 * set nr_rings to 1 to force preemption off
+	 */
+	a6xx_preempt_fini(gpu);
+	gpu->nr_rings = 1;
+
+	DRM_DEV_ERROR(&gpu->pdev->dev,
+				  "preemption init failed, disabling preemption\n");
+
+	return;
+}
diff --git a/drivers/gpu/drm/msm/msm_ringbuffer.h b/drivers/gpu/drm/msm/msm_ringbuffer.h
index 174f83137a49..d1e49f701c81 100644
--- a/drivers/gpu/drm/msm/msm_ringbuffer.h
+++ b/drivers/gpu/drm/msm/msm_ringbuffer.h
@@ -36,6 +36,7 @@  struct msm_rbmemptrs {
 
 	volatile struct msm_gpu_submit_stats stats[MSM_GPU_SUBMIT_STATS_COUNT];
 	volatile u64 ttbr0;
+	volatile u32 context_idr;
 };
 
 struct msm_cp_state {
@@ -101,6 +102,12 @@  struct msm_ringbuffer {
 	 */
 	spinlock_t preempt_lock;
 
+	/*
+	 * Whether we skipped writing wptr and it needs to be updated in the
+	 * future when the ring becomes current.
+	 */
+	bool restore_wptr;
+
 	/**
 	 * cur_ctx_seqno:
 	 *