Re: [PATCH v4] drm/panthor: Add DEV_QUERY_TIMESTAMP_INFO dev query

[Boris Brezillon <boris.brezillon@collabora.com>]

On Fri, 30 Aug 2024 10:03:50 +0200
Mary Guillemard <mary.guillemard@collabora.com> wrote:

> Expose timestamp information supported by the GPU with a new device
> query.
> 
> 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.
> 
> Since this extends the uAPI and because userland needs a way to advertise
> those features conditionally, this also bumps the driver minor version.
> 
> v2:
> - Rewrote to use GPU timestamp register
> - Added timestamp_offset to drm_panthor_timestamp_info
> - Add missing include for arch_timer_get_cntfrq
> - Rework commit message
> 
> v3:
> - Add panthor_gpu_read_64bit_counter
> - Change panthor_gpu_read_timestamp to use
>   panthor_gpu_read_64bit_counter
> 
> v4:
> - Fix multiple typos in uAPI documentation
> - Mention behavior when the timestamp frequency is unknown
> - Use u64 instead of unsigned long long
>   for panthor_gpu_read_timestamp
> - Apply r-b from Mihail
> 
> Signed-off-by: Mary Guillemard <mary.guillemard@collabora.com>
> Reviewed-by: Mihail Atanassov <mihail.atanassov@arm.com>

Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>

> ---
>  drivers/gpu/drm/panthor/panthor_drv.c | 43 +++++++++++++++++++++++-
>  drivers/gpu/drm/panthor/panthor_gpu.c | 47 +++++++++++++++++++++++++++
>  drivers/gpu/drm/panthor/panthor_gpu.h |  4 +++
>  include/uapi/drm/panthor_drm.h        | 22 +++++++++++++
>  4 files changed, 115 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_drv.c b/drivers/gpu/drm/panthor/panthor_drv.c
> index b5e7b919f241..444e3bb1cfb5 100644
> --- a/drivers/gpu/drm/panthor/panthor_drv.c
> +++ b/drivers/gpu/drm/panthor/panthor_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/list.h>
>  #include <linux/module.h>
>  #include <linux/of_platform.h>
> @@ -164,6 +168,7 @@ panthor_get_uobj_array(const struct drm_panthor_obj_array *in, u32 min_stride,
>  	_Generic(_obj_name, \
>  		 PANTHOR_UOBJ_DECL(struct drm_panthor_gpu_info, tiler_present), \
>  		 PANTHOR_UOBJ_DECL(struct drm_panthor_csif_info, pad), \
> +		 PANTHOR_UOBJ_DECL(struct drm_panthor_timestamp_info, current_timestamp), \
>  		 PANTHOR_UOBJ_DECL(struct drm_panthor_sync_op, timeline_value), \
>  		 PANTHOR_UOBJ_DECL(struct drm_panthor_queue_submit, syncs), \
>  		 PANTHOR_UOBJ_DECL(struct drm_panthor_queue_create, ringbuf_size), \
> @@ -750,10 +755,33 @@ static void panthor_submit_ctx_cleanup(struct panthor_submit_ctx *ctx,
>  	kvfree(ctx->jobs);
>  }
>  
> +static int panthor_query_timestamp_info(struct panthor_device *ptdev,
> +					struct drm_panthor_timestamp_info *arg)
> +{
> +	int ret;
> +
> +	ret = pm_runtime_resume_and_get(ptdev->base.dev);
> +	if (ret)
> +		return ret;
> +
> +#ifdef CONFIG_ARM_ARCH_TIMER
> +	arg->timestamp_frequency = arch_timer_get_cntfrq();
> +#else
> +	arg->timestamp_frequency = 0;
> +#endif
> +	arg->current_timestamp = panthor_gpu_read_timestamp(ptdev);
> +	arg->timestamp_offset = panthor_gpu_read_timestamp_offset(ptdev);
> +
> +	pm_runtime_put(ptdev->base.dev);
> +	return 0;
> +}
> +
>  static int panthor_ioctl_dev_query(struct drm_device *ddev, void *data, struct drm_file *file)
>  {
>  	struct panthor_device *ptdev = container_of(ddev, struct panthor_device, base);
>  	struct drm_panthor_dev_query *args = data;
> +	struct drm_panthor_timestamp_info timestamp_info;
> +	int ret;
>  
>  	if (!args->pointer) {
>  		switch (args->type) {
> @@ -765,6 +793,10 @@ static int panthor_ioctl_dev_query(struct drm_device *ddev, void *data, struct d
>  			args->size = sizeof(ptdev->csif_info);
>  			return 0;
>  
> +		case DRM_PANTHOR_DEV_QUERY_TIMESTAMP_INFO:
> +			args->size = sizeof(timestamp_info);
> +			return 0;
> +
>  		default:
>  			return -EINVAL;
>  		}
> @@ -777,6 +809,14 @@ static int panthor_ioctl_dev_query(struct drm_device *ddev, void *data, struct d
>  	case DRM_PANTHOR_DEV_QUERY_CSIF_INFO:
>  		return PANTHOR_UOBJ_SET(args->pointer, args->size, ptdev->csif_info);
>  
> +	case DRM_PANTHOR_DEV_QUERY_TIMESTAMP_INFO:
> +		ret = panthor_query_timestamp_info(ptdev, &timestamp_info);
> +
> +		if (ret)
> +			return ret;
> +
> +		return PANTHOR_UOBJ_SET(args->pointer, args->size, timestamp_info);
> +
>  	default:
>  		return -EINVAL;
>  	}
> @@ -1372,6 +1412,7 @@ static void panthor_debugfs_init(struct drm_minor *minor)
>  /*
>   * PanCSF driver version:
>   * - 1.0 - initial interface
> + * - 1.1 - adds DEV_QUERY_TIMESTAMP_INFO query
>   */
>  static const struct drm_driver panthor_drm_driver = {
>  	.driver_features = DRIVER_RENDER | DRIVER_GEM | DRIVER_SYNCOBJ |
> @@ -1385,7 +1426,7 @@ static const struct drm_driver panthor_drm_driver = {
>  	.desc = "Panthor DRM driver",
>  	.date = "20230801",
>  	.major = 1,
> -	.minor = 0,
> +	.minor = 1,
>  
>  	.gem_create_object = panthor_gem_create_object,
>  	.gem_prime_import_sg_table = drm_gem_shmem_prime_import_sg_table,
> diff --git a/drivers/gpu/drm/panthor/panthor_gpu.c b/drivers/gpu/drm/panthor/panthor_gpu.c
> index 5251d8764e7d..2d3529a0b156 100644
> --- a/drivers/gpu/drm/panthor/panthor_gpu.c
> +++ b/drivers/gpu/drm/panthor/panthor_gpu.c
> @@ -480,3 +480,50 @@ void panthor_gpu_resume(struct panthor_device *ptdev)
>  	panthor_gpu_irq_resume(&ptdev->gpu->irq, GPU_INTERRUPTS_MASK);
>  	panthor_gpu_l2_power_on(ptdev);
>  }
> +
> +/**
> + * panthor_gpu_read_64bit_counter() - Read a 64-bit counter at a given offset.
> + * @ptdev: Device.
> + * @reg: The offset of the register to read.
> + *
> + * Return: The counter value.
> + */
> +static u64
> +panthor_gpu_read_64bit_counter(struct panthor_device *ptdev, u32 reg)
> +{
> +	u32 hi, lo;
> +
> +	do {
> +		hi = gpu_read(ptdev, reg + 0x4);
> +		lo = gpu_read(ptdev, reg);
> +	} while (hi != gpu_read(ptdev, reg + 0x4));
> +
> +	return ((u64)hi << 32) | lo;
> +}
> +
> +/**
> + * panthor_gpu_read_timestamp() - Read the timestamp register.
> + * @ptdev: Device.
> + *
> + * Return: The GPU timestamp value.
> + */
> +u64 panthor_gpu_read_timestamp(struct panthor_device *ptdev)
> +{
> +	return panthor_gpu_read_64bit_counter(ptdev, GPU_TIMESTAMP_LO);
> +}
> +
> +/**
> + * panthor_gpu_read_timestamp_offset() - Read the timestamp offset register.
> + * @ptdev: Device.
> + *
> + * Return: The GPU timestamp offset value.
> + */
> +u64 panthor_gpu_read_timestamp_offset(struct panthor_device *ptdev)
> +{
> +	u32 hi, lo;
> +
> +	hi = gpu_read(ptdev, GPU_TIMESTAMP_OFFSET_HI);
> +	lo = gpu_read(ptdev, GPU_TIMESTAMP_OFFSET_LO);
> +
> +	return ((u64)hi << 32) | lo;
> +}
> diff --git a/drivers/gpu/drm/panthor/panthor_gpu.h b/drivers/gpu/drm/panthor/panthor_gpu.h
> index bba7555dd3c6..7f6133a66127 100644
> --- a/drivers/gpu/drm/panthor/panthor_gpu.h
> +++ b/drivers/gpu/drm/panthor/panthor_gpu.h
> @@ -5,6 +5,8 @@
>  #ifndef __PANTHOR_GPU_H__
>  #define __PANTHOR_GPU_H__
>  
> +#include <linux/types.h>
> +
>  struct panthor_device;
>  
>  int panthor_gpu_init(struct panthor_device *ptdev);
> @@ -48,5 +50,7 @@ int panthor_gpu_l2_power_on(struct panthor_device *ptdev);
>  int panthor_gpu_flush_caches(struct panthor_device *ptdev,
>  			     u32 l2, u32 lsc, u32 other);
>  int panthor_gpu_soft_reset(struct panthor_device *ptdev);
> +u64 panthor_gpu_read_timestamp(struct panthor_device *ptdev);
> +u64 panthor_gpu_read_timestamp_offset(struct panthor_device *ptdev);
>  
>  #endif
> diff --git a/include/uapi/drm/panthor_drm.h b/include/uapi/drm/panthor_drm.h
> index 926b1deb1116..95e3a984c69a 100644
> --- a/include/uapi/drm/panthor_drm.h
> +++ b/include/uapi/drm/panthor_drm.h
> @@ -260,6 +260,9 @@ enum drm_panthor_dev_query_type {
>  
>  	/** @DRM_PANTHOR_DEV_QUERY_CSIF_INFO: Query command-stream interface information. */
>  	DRM_PANTHOR_DEV_QUERY_CSIF_INFO,
> +
> +	/** @DRM_PANTHOR_DEV_QUERY_TIMESTAMP_INFO: Query timestamp information. */
> +	DRM_PANTHOR_DEV_QUERY_TIMESTAMP_INFO,
>  };
>  
>  /**
> @@ -377,6 +380,25 @@ struct drm_panthor_csif_info {
>  	__u32 pad;
>  };
>  
> +/**
> + * struct drm_panthor_timestamp_info - Timestamp information
> + *
> + * Structure grouping all queryable information relating to the GPU timestamp.
> + */
> +struct drm_panthor_timestamp_info {
> +	/**
> +	 * @timestamp_frequency: The frequency of the timestamp timer or 0 if
> +	 * unknown.
> +	 */
> +	__u64 timestamp_frequency;
> +
> +	/** @current_timestamp: The current timestamp. */
> +	__u64 current_timestamp;
> +
> +	/** @timestamp_offset: The offset of the timestamp timer. */
> +	__u64 timestamp_offset;
> +};
> +
>  /**
>   * struct drm_panthor_dev_query - Arguments passed to DRM_PANTHOR_IOCTL_DEV_QUERY
>   */
> 
> base-commit: e75356ef5baef69e9f577023c453d91a902dc082