diff mbox series

[v2,5/5] drm/panthor: Fix the fast-reset logic

Message ID 20241128110255.3182366-6-boris.brezillon@collabora.com (mailing list archive)
State New
Headers show
Series drm/panthor: Be robust against failures in the resume path | expand

Commit Message

Boris Brezillon Nov. 28, 2024, 11:02 a.m. UTC
If we do a GPU soft-reset, that's no longer fast reset. This also means
the slow reset fallback doesn't work because the MCU state is only reset
after a GPU soft-reset.

Let's move the retry logic to panthor_device_resume() to issue a
soft-reset between the fast and slow attempts, and patch
panthor_gpu_suspend() to only power-off the L2 when a fast reset is
requested.

v2:
- Add R-b

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
---
 drivers/gpu/drm/panthor/panthor_device.c | 32 ++++++++++----
 drivers/gpu/drm/panthor/panthor_device.h | 11 +++++
 drivers/gpu/drm/panthor/panthor_fw.c     | 54 ++++++------------------
 drivers/gpu/drm/panthor/panthor_gpu.c    | 11 ++---
 4 files changed, 53 insertions(+), 55 deletions(-)
diff mbox series

Patch

diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
index 0362101ea896..2c817e65e6be 100644
--- a/drivers/gpu/drm/panthor/panthor_device.c
+++ b/drivers/gpu/drm/panthor/panthor_device.c
@@ -431,6 +431,22 @@  int panthor_device_mmap_io(struct panthor_device *ptdev, struct vm_area_struct *
 	return 0;
 }
 
+static int panthor_device_resume_hw_components(struct panthor_device *ptdev)
+{
+	int ret;
+
+	panthor_gpu_resume(ptdev);
+	panthor_mmu_resume(ptdev);
+
+	ret = panthor_fw_resume(ptdev);
+	if (!ret)
+		return 0;
+
+	panthor_mmu_suspend(ptdev);
+	panthor_gpu_suspend(ptdev);
+	return ret;
+}
+
 int panthor_device_resume(struct device *dev)
 {
 	struct panthor_device *ptdev = dev_get_drvdata(dev);
@@ -457,16 +473,16 @@  int panthor_device_resume(struct device *dev)
 
 	if (panthor_device_is_initialized(ptdev) &&
 	    drm_dev_enter(&ptdev->base, &cookie)) {
-		panthor_gpu_resume(ptdev);
-		panthor_mmu_resume(ptdev);
-		ret = panthor_fw_resume(ptdev);
-		if (!drm_WARN_ON(&ptdev->base, ret)) {
-			panthor_sched_resume(ptdev);
-		} else {
-			panthor_mmu_suspend(ptdev);
-			panthor_gpu_suspend(ptdev);
+		ret = panthor_device_resume_hw_components(ptdev);
+		if (ret && ptdev->reset.fast) {
+			drm_err(&ptdev->base, "Fast reset failed, trying a slow reset");
+			ptdev->reset.fast = false;
+			ret = panthor_device_resume_hw_components(ptdev);
 		}
 
+		if (!ret)
+			panthor_sched_resume(ptdev);
+
 		drm_dev_exit(cookie);
 
 		if (ret)
diff --git a/drivers/gpu/drm/panthor/panthor_device.h b/drivers/gpu/drm/panthor/panthor_device.h
index b6c4f25a5d6e..da6574021664 100644
--- a/drivers/gpu/drm/panthor/panthor_device.h
+++ b/drivers/gpu/drm/panthor/panthor_device.h
@@ -157,6 +157,17 @@  struct panthor_device {
 
 		/** @pending: Set to true if a reset is pending. */
 		atomic_t pending;
+
+		/**
+		 * @fast: True if the post_reset logic can proceed with a fast reset.
+		 *
+		 * A fast reset is just a reset where the driver doesn't reload the FW sections.
+		 *
+		 * Any time the firmware is properly suspended, a fast reset can take place.
+		 * On the other hand, if the halt operation failed, the driver will reload
+		 * all FW sections to make sure we start from a fresh state.
+		 */
+		bool fast;
 	} reset;
 
 	/** @pm: Power management related data. */
diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
index f3d3d8fbe13d..a3d11d32b71c 100644
--- a/drivers/gpu/drm/panthor/panthor_fw.c
+++ b/drivers/gpu/drm/panthor/panthor_fw.c
@@ -263,17 +263,6 @@  struct panthor_fw {
 	/** @booted: True is the FW is booted */
 	bool booted;
 
-	/**
-	 * @fast_reset: True if the post_reset logic can proceed with a fast reset.
-	 *
-	 * A fast reset is just a reset where the driver doesn't reload the FW sections.
-	 *
-	 * Any time the firmware is properly suspended, a fast reset can take place.
-	 * On the other hand, if the halt operation failed, the driver will reload
-	 * all sections to make sure we start from a fresh state.
-	 */
-	bool fast_reset;
-
 	/** @irq: Job irq data. */
 	struct panthor_irq irq;
 };
@@ -1090,7 +1079,7 @@  void panthor_fw_pre_reset(struct panthor_device *ptdev, bool on_hang)
 	/* Make sure we won't be woken up by a ping. */
 	cancel_delayed_work_sync(&ptdev->fw->watchdog.ping_work);
 
-	ptdev->fw->fast_reset = false;
+	ptdev->reset.fast = false;
 
 	if (!on_hang) {
 		struct panthor_fw_global_iface *glb_iface = panthor_fw_get_glb_iface(ptdev);
@@ -1100,7 +1089,7 @@  void panthor_fw_pre_reset(struct panthor_device *ptdev, bool on_hang)
 		gpu_write(ptdev, CSF_DOORBELL(CSF_GLB_DOORBELL_ID), 1);
 		if (!readl_poll_timeout(ptdev->iomem + MCU_STATUS, status,
 					status == MCU_STATUS_HALT, 10, 100000)) {
-			ptdev->fw->fast_reset = true;
+			ptdev->reset.fast = true;
 		} else {
 			drm_warn(&ptdev->base, "Failed to cleanly suspend MCU");
 		}
@@ -1125,49 +1114,30 @@  int panthor_fw_post_reset(struct panthor_device *ptdev)
 	if (ret)
 		return ret;
 
-	/* If this is a fast reset, try to start the MCU without reloading
-	 * the FW sections. If it fails, go for a full reset.
-	 */
-	if (ptdev->fw->fast_reset) {
+	if (!ptdev->reset.fast) {
+		/* On a slow reset, reload all sections, including RO ones.
+		 * We're not supposed to end up here anyway, let's just assume
+		 * the overhead of reloading everything is acceptable.
+		 */
+		panthor_reload_fw_sections(ptdev, true);
+	} else {
 		/* The FW detects 0 -> 1 transitions. Make sure we reset
 		 * the HALT bit before the FW is rebooted.
 		 * This is not needed on a slow reset because FW sections are
 		 * re-initialized.
 		 */
 		struct panthor_fw_global_iface *glb_iface = panthor_fw_get_glb_iface(ptdev);
+
 		panthor_fw_update_reqs(glb_iface, req, 0, GLB_HALT);
-
-		ret = panthor_fw_start(ptdev);
-		if (!ret)
-			goto out;
-
-		/* Forcibly reset the MCU and force a slow reset, so we get a
-		 * fresh boot on the next panthor_fw_start() call.
-		 */
-		panthor_fw_stop(ptdev);
-		ptdev->fw->fast_reset = false;
-		drm_err(&ptdev->base, "FW fast reset failed, trying a slow reset");
-
-		ret = panthor_vm_flush_all(ptdev->fw->vm);
-		if (ret) {
-			drm_err(&ptdev->base, "FW slow reset failed (couldn't flush FW's AS l2cache)");
-			return ret;
-		}
 	}
 
-	/* Reload all sections, including RO ones. We're not supposed
-	 * to end up here anyway, let's just assume the overhead of
-	 * reloading everything is acceptable.
-	 */
-	panthor_reload_fw_sections(ptdev, true);
-
 	ret = panthor_fw_start(ptdev);
 	if (ret) {
-		drm_err(&ptdev->base, "FW slow reset failed (couldn't start the FW )");
+		drm_err(&ptdev->base, "FW %s reset failed",
+			ptdev->reset.fast ?  "fast" : "slow");
 		return ret;
 	}
 
-out:
 	/* We must re-initialize the global interface even on fast-reset. */
 	panthor_fw_init_global_iface(ptdev);
 	return 0;
diff --git a/drivers/gpu/drm/panthor/panthor_gpu.c b/drivers/gpu/drm/panthor/panthor_gpu.c
index ee85a371bc38..671049020afa 100644
--- a/drivers/gpu/drm/panthor/panthor_gpu.c
+++ b/drivers/gpu/drm/panthor/panthor_gpu.c
@@ -470,11 +470,12 @@  int panthor_gpu_soft_reset(struct panthor_device *ptdev)
  */
 void panthor_gpu_suspend(struct panthor_device *ptdev)
 {
-	/*
-	 * It may be preferable to simply power down the L2, but for now just
-	 * soft-reset which will leave the L2 powered down.
-	 */
-	panthor_gpu_soft_reset(ptdev);
+	/* On a fast reset, simply power down the L2. */
+	if (!ptdev->reset.fast)
+		panthor_gpu_soft_reset(ptdev);
+	else
+		panthor_gpu_power_off(ptdev, L2, 1, 20000);
+
 	panthor_gpu_irq_suspend(&ptdev->gpu->irq);
 }