diff mbox series

[v2,1/2] drm/panfrost: Add SYSTEM_TIMESTAMP and SYSTEM_TIMESTAMP_FREQUENCY parameters

Message ID 20240814112121.61137-3-mary.guillemard@collabora.com (mailing list archive)
State New, archived
Headers show
Series drm/panfrost: Wire cycle counters and timestamp info to userspace | expand

Commit Message

Mary Guillemard Aug. 14, 2024, 11:21 a.m. UTC 
Expose system timestamp and frequency supported by the GPU.

Mali uses an external timer as GPU system time. On ARM, this is wired to
the generic arch timer so we wire cntfrq_el0 as device frequency.

This new uAPI will be used in Mesa to implement timestamp queries and
VK_KHR_calibrated_timestamps.

v2:
- Rewrote to use GPU timestamp register
- Add missing include for arch_timer_get_cntfrq
- Rework commit message

Signed-off-by: Mary Guillemard <mary.guillemard@collabora.com>
---
 drivers/gpu/drm/panfrost/panfrost_drv.c  | 35 ++++++++++++++++++++++++
 drivers/gpu/drm/panfrost/panfrost_gpu.c  | 12 ++++++++
 drivers/gpu/drm/panfrost/panfrost_gpu.h  |  1 +
 drivers/gpu/drm/panfrost/panfrost_regs.h |  2 ++
 include/uapi/drm/panfrost_drm.h          |  2 ++
 5 files changed, 52 insertions(+)

Comments

Steven Price Aug. 15, 2024, 2:31 p.m. UTC | #1 
On 14/08/2024 12:21, Mary Guillemard wrote:
> Expose system timestamp and frequency supported by the GPU.
> 
> Mali uses an external timer as GPU system time. On ARM, this is wired to
> the generic arch timer so we wire cntfrq_el0 as device frequency.
> 
> This new uAPI will be used in Mesa to implement timestamp queries and
> VK_KHR_calibrated_timestamps.
> 
> v2:
> - Rewrote to use GPU timestamp register
> - Add missing include for arch_timer_get_cntfrq
> - Rework commit message
> 
> Signed-off-by: Mary Guillemard <mary.guillemard@collabora.com>
> ---
>  drivers/gpu/drm/panfrost/panfrost_drv.c  | 35 ++++++++++++++++++++++++
>  drivers/gpu/drm/panfrost/panfrost_gpu.c  | 12 ++++++++
>  drivers/gpu/drm/panfrost/panfrost_gpu.h  |  1 +
>  drivers/gpu/drm/panfrost/panfrost_regs.h |  2 ++
>  include/uapi/drm/panfrost_drm.h          |  2 ++
>  5 files changed, 52 insertions(+)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
> index 671eed4ad890..83696d06d697 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_drv.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
> @@ -3,6 +3,10 @@
>  /* Copyright 2019 Linaro, Ltd., Rob Herring <robh@kernel.org> */
>  /* Copyright 2019 Collabora ltd. */
>  
> +#ifdef CONFIG_ARM_ARCH_TIMER
> +#include <asm/arch_timer.h>
> +#endif
> +
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/pagemap.h>
> @@ -24,10 +28,26 @@
>  static bool unstable_ioctls;
>  module_param_unsafe(unstable_ioctls, bool, 0600);
>  
> +static int panfrost_ioctl_query_timestamp(struct panfrost_device *pfdev,
> +					  u64 *arg)
> +{
> +	int ret;
> +
> +	ret = pm_runtime_resume_and_get(pfdev->dev);
> +	if (ret)
> +		return ret;
> +
> +	*arg = panfrost_timestamp_read(pfdev);
> +
> +	pm_runtime_put(pfdev->dev);
> +	return 0;
> +}
> +
>  static int panfrost_ioctl_get_param(struct drm_device *ddev, void *data, struct drm_file *file)
>  {
>  	struct drm_panfrost_get_param *param = data;
>  	struct panfrost_device *pfdev = ddev->dev_private;
> +	int ret;
>  
>  	if (param->pad != 0)
>  		return -EINVAL;
> @@ -69,6 +89,21 @@ static int panfrost_ioctl_get_param(struct drm_device *ddev, void *data, struct
>  		PANFROST_FEATURE_ARRAY(JS_FEATURES, js_features, 15);
>  		PANFROST_FEATURE(NR_CORE_GROUPS, nr_core_groups);
>  		PANFROST_FEATURE(THREAD_TLS_ALLOC, thread_tls_alloc);
> +
> +	case DRM_PANFROST_PARAM_SYSTEM_TIMESTAMP:
> +		ret = panfrost_ioctl_query_timestamp(pfdev, &param->value);
> +		if (ret)
> +			return ret;
> +		break;
> +
> +	case DRM_PANFROST_PARAM_SYSTEM_TIMESTAMP_FREQUENCY:
> +#ifdef CONFIG_ARM_ARCH_TIMER
> +		param->value = arch_timer_get_cntfrq();
> +#else
> +		param->value = 0;
> +#endif
> +		break;
> +
>  	default:
>  		return -EINVAL;
>  	}
> diff --git a/drivers/gpu/drm/panfrost/panfrost_gpu.c b/drivers/gpu/drm/panfrost/panfrost_gpu.c
> index fd8e44992184..92de71725f53 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_gpu.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_gpu.c
> @@ -380,6 +380,18 @@ unsigned long long panfrost_cycle_counter_read(struct panfrost_device *pfdev)
>  	return ((u64)hi << 32) | lo;
>  }
>  
> +unsigned long long panfrost_timestamp_read(struct panfrost_device *pfdev)
> +{
> +	u32 hi, lo;
> +
> +	panfrost_cycle_counter_get(pfdev);
> +	hi = gpu_read(pfdev, GPU_TIMESTAMP_HI);
> +	lo = gpu_read(pfdev, GPU_TIMESTAMP_LO);

To get a reliable timestamp you need to use the hi-lo-hi trick:

do {
	hi = gpu_read(pfdev, GPU_TIMESTAMP_HI);
	lo = gpu_read(pfdev, GPU_TIMESTAMP_LO);
} while (hi != gpu_read(pfdev, GPU_TIMESTAMP_HI);

Otherwise if you read around the point of overflowing from LO to HI
you'll get a value which is 2^32 out - see panfrost_cycle_counter_read().

I'm also a little concerned that we have a different API here -
panfrost_cycle_counter_read() assumes that the cycle counter has been
enabled by the caller, but this doesn't. It would be nice to keep these
two functions consistent (i.e. move the get/put into
panfrost_ioctl_query_timestamp()).

Steve

> +	panfrost_cycle_counter_put(pfdev);
> +
> +	return ((u64)hi << 32) | lo;
> +}
> +
>  static u64 panfrost_get_core_mask(struct panfrost_device *pfdev)
>  {
>  	u64 core_mask;
> diff --git a/drivers/gpu/drm/panfrost/panfrost_gpu.h b/drivers/gpu/drm/panfrost/panfrost_gpu.h
> index d841b86504ea..b4fef11211d5 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_gpu.h
> +++ b/drivers/gpu/drm/panfrost/panfrost_gpu.h
> @@ -20,6 +20,7 @@ void panfrost_gpu_suspend_irq(struct panfrost_device *pfdev);
>  void panfrost_cycle_counter_get(struct panfrost_device *pfdev);
>  void panfrost_cycle_counter_put(struct panfrost_device *pfdev);
>  unsigned long long panfrost_cycle_counter_read(struct panfrost_device *pfdev);
> +unsigned long long panfrost_timestamp_read(struct panfrost_device *pfdev);
>  
>  void panfrost_gpu_amlogic_quirk(struct panfrost_device *pfdev);
>  
> diff --git a/drivers/gpu/drm/panfrost/panfrost_regs.h b/drivers/gpu/drm/panfrost/panfrost_regs.h
> index c25743b05c55..c7bba476ab3f 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_regs.h
> +++ b/drivers/gpu/drm/panfrost/panfrost_regs.h
> @@ -78,6 +78,8 @@
>  
>  #define GPU_CYCLE_COUNT_LO		0x90
>  #define GPU_CYCLE_COUNT_HI		0x94
> +#define GPU_TIMESTAMP_LO		0x98
> +#define GPU_TIMESTAMP_HI		0x9C
>  
>  #define GPU_THREAD_MAX_THREADS		0x0A0	/* (RO) Maximum number of threads per core */
>  #define GPU_THREAD_MAX_WORKGROUP_SIZE	0x0A4	/* (RO) Maximum workgroup size */
> diff --git a/include/uapi/drm/panfrost_drm.h b/include/uapi/drm/panfrost_drm.h
> index 9f231d40a146..52b050e2b660 100644
> --- a/include/uapi/drm/panfrost_drm.h
> +++ b/include/uapi/drm/panfrost_drm.h
> @@ -172,6 +172,8 @@ enum drm_panfrost_param {
>  	DRM_PANFROST_PARAM_NR_CORE_GROUPS,
>  	DRM_PANFROST_PARAM_THREAD_TLS_ALLOC,
>  	DRM_PANFROST_PARAM_AFBC_FEATURES,
> +	DRM_PANFROST_PARAM_SYSTEM_TIMESTAMP,
> +	DRM_PANFROST_PARAM_SYSTEM_TIMESTAMP_FREQUENCY,
>  };
>  
>  struct drm_panfrost_get_param {
diff mbox series

Patch

diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
index 671eed4ad890..83696d06d697 100644
--- a/drivers/gpu/drm/panfrost/panfrost_drv.c
+++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
@@ -3,6 +3,10 @@ 
 /* Copyright 2019 Linaro, Ltd., Rob Herring <robh@kernel.org> */
 /* Copyright 2019 Collabora ltd. */
 
+#ifdef CONFIG_ARM_ARCH_TIMER
+#include <asm/arch_timer.h>
+#endif
+
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/pagemap.h>
@@ -24,10 +28,26 @@ 
 static bool unstable_ioctls;
 module_param_unsafe(unstable_ioctls, bool, 0600);
 
+static int panfrost_ioctl_query_timestamp(struct panfrost_device *pfdev,
+					  u64 *arg)
+{
+	int ret;
+
+	ret = pm_runtime_resume_and_get(pfdev->dev);
+	if (ret)
+		return ret;
+
+	*arg = panfrost_timestamp_read(pfdev);
+
+	pm_runtime_put(pfdev->dev);
+	return 0;
+}
+
 static int panfrost_ioctl_get_param(struct drm_device *ddev, void *data, struct drm_file *file)
 {
 	struct drm_panfrost_get_param *param = data;
 	struct panfrost_device *pfdev = ddev->dev_private;
+	int ret;
 
 	if (param->pad != 0)
 		return -EINVAL;
@@ -69,6 +89,21 @@  static int panfrost_ioctl_get_param(struct drm_device *ddev, void *data, struct
 		PANFROST_FEATURE_ARRAY(JS_FEATURES, js_features, 15);
 		PANFROST_FEATURE(NR_CORE_GROUPS, nr_core_groups);
 		PANFROST_FEATURE(THREAD_TLS_ALLOC, thread_tls_alloc);
+
+	case DRM_PANFROST_PARAM_SYSTEM_TIMESTAMP:
+		ret = panfrost_ioctl_query_timestamp(pfdev, &param->value);
+		if (ret)
+			return ret;
+		break;
+
+	case DRM_PANFROST_PARAM_SYSTEM_TIMESTAMP_FREQUENCY:
+#ifdef CONFIG_ARM_ARCH_TIMER
+		param->value = arch_timer_get_cntfrq();
+#else
+		param->value = 0;
+#endif
+		break;
+
 	default:
 		return -EINVAL;
 	}
diff --git a/drivers/gpu/drm/panfrost/panfrost_gpu.c b/drivers/gpu/drm/panfrost/panfrost_gpu.c
index fd8e44992184..92de71725f53 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gpu.c
+++ b/drivers/gpu/drm/panfrost/panfrost_gpu.c
@@ -380,6 +380,18 @@  unsigned long long panfrost_cycle_counter_read(struct panfrost_device *pfdev)
 	return ((u64)hi << 32) | lo;
 }
 
+unsigned long long panfrost_timestamp_read(struct panfrost_device *pfdev)
+{
+	u32 hi, lo;
+
+	panfrost_cycle_counter_get(pfdev);
+	hi = gpu_read(pfdev, GPU_TIMESTAMP_HI);
+	lo = gpu_read(pfdev, GPU_TIMESTAMP_LO);
+	panfrost_cycle_counter_put(pfdev);
+
+	return ((u64)hi << 32) | lo;
+}
+
 static u64 panfrost_get_core_mask(struct panfrost_device *pfdev)
 {
 	u64 core_mask;
diff --git a/drivers/gpu/drm/panfrost/panfrost_gpu.h b/drivers/gpu/drm/panfrost/panfrost_gpu.h
index d841b86504ea..b4fef11211d5 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gpu.h
+++ b/drivers/gpu/drm/panfrost/panfrost_gpu.h
@@ -20,6 +20,7 @@  void panfrost_gpu_suspend_irq(struct panfrost_device *pfdev);
 void panfrost_cycle_counter_get(struct panfrost_device *pfdev);
 void panfrost_cycle_counter_put(struct panfrost_device *pfdev);
 unsigned long long panfrost_cycle_counter_read(struct panfrost_device *pfdev);
+unsigned long long panfrost_timestamp_read(struct panfrost_device *pfdev);
 
 void panfrost_gpu_amlogic_quirk(struct panfrost_device *pfdev);
 
diff --git a/drivers/gpu/drm/panfrost/panfrost_regs.h b/drivers/gpu/drm/panfrost/panfrost_regs.h
index c25743b05c55..c7bba476ab3f 100644
--- a/drivers/gpu/drm/panfrost/panfrost_regs.h
+++ b/drivers/gpu/drm/panfrost/panfrost_regs.h
@@ -78,6 +78,8 @@ 
 
 #define GPU_CYCLE_COUNT_LO		0x90
 #define GPU_CYCLE_COUNT_HI		0x94
+#define GPU_TIMESTAMP_LO		0x98
+#define GPU_TIMESTAMP_HI		0x9C
 
 #define GPU_THREAD_MAX_THREADS		0x0A0	/* (RO) Maximum number of threads per core */
 #define GPU_THREAD_MAX_WORKGROUP_SIZE	0x0A4	/* (RO) Maximum workgroup size */
diff --git a/include/uapi/drm/panfrost_drm.h b/include/uapi/drm/panfrost_drm.h
index 9f231d40a146..52b050e2b660 100644
--- a/include/uapi/drm/panfrost_drm.h
+++ b/include/uapi/drm/panfrost_drm.h
@@ -172,6 +172,8 @@  enum drm_panfrost_param {
 	DRM_PANFROST_PARAM_NR_CORE_GROUPS,
 	DRM_PANFROST_PARAM_THREAD_TLS_ALLOC,
 	DRM_PANFROST_PARAM_AFBC_FEATURES,
+	DRM_PANFROST_PARAM_SYSTEM_TIMESTAMP,
+	DRM_PANFROST_PARAM_SYSTEM_TIMESTAMP_FREQUENCY,
 };
 
 struct drm_panfrost_get_param {