[PATCH v2 5/5] drm/vkms: Implement CRC debugfs API

Sean Paul seanpaul at chromium.org
Mon Jul 16 18:22:56 UTC 2018


On Sat, Jul 14, 2018 at 03:23:32PM +0300, Haneen Mohammed wrote:
> Implement the set_crc_source() callback.
> Compute CRC using crc32 on the visible part of the framebuffer.
> Use ordered workqueue to compute and add CRC at the end of a vblank.
> 
> Use appropriate synchronization methods since the crc computation must
> be atomic wrt the generated vblank event for a given atomic update,
> 
> Signed-off-by: Haneen Mohammed <hamohammed.sa at gmail.com>

Hey Haneen,
Thanks for revising this patch set. Things are looking good across the series,
just a few more comments :-)

> ---
> Changes in v2:
> - Include this patch in this patchset.
> 
>  drivers/gpu/drm/vkms/Makefile     |  2 +-
>  drivers/gpu/drm/vkms/vkms_crtc.c  | 60 ++++++++++++++++++++++++++-----
>  drivers/gpu/drm/vkms/vkms_drv.c   |  1 +
>  drivers/gpu/drm/vkms/vkms_drv.h   | 21 +++++++++++
>  drivers/gpu/drm/vkms/vkms_plane.c | 10 ++++++
>  5 files changed, 85 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vkms/Makefile b/drivers/gpu/drm/vkms/Makefile
> index 986297da51bf..37966914f70b 100644
> --- a/drivers/gpu/drm/vkms/Makefile
> +++ b/drivers/gpu/drm/vkms/Makefile
> @@ -1,3 +1,3 @@
> -vkms-y := vkms_drv.o vkms_plane.o vkms_output.o vkms_crtc.o vkms_gem.o
> +vkms-y := vkms_drv.o vkms_plane.o vkms_output.o vkms_crtc.o vkms_gem.o vkms_crc.o
>  
>  obj-$(CONFIG_DRM_VKMS) += vkms.o
> diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
> index 26babb85ca77..f3a674db33b8 100644
> --- a/drivers/gpu/drm/vkms/vkms_crtc.c
> +++ b/drivers/gpu/drm/vkms/vkms_crtc.c
> @@ -10,18 +10,36 @@
>  #include <drm/drm_atomic_helper.h>
>  #include <drm/drm_crtc_helper.h>
>  
> -static enum hrtimer_restart vkms_vblank_simulate(struct hrtimer *timer)
> +static void _vblank_handle(struct vkms_output *output)
>  {
> -	struct vkms_output *output = container_of(timer, struct vkms_output,
> -						  vblank_hrtimer);
>  	struct drm_crtc *crtc = &output->crtc;
> -	int ret_overrun;
> +	struct vkms_crtc_state *state = to_vkms_crtc_state(crtc->state);
>  	bool ret;
>  
> +	int crc_enabled = 0;
> +
> +	spin_lock(&output->lock);
> +	crc_enabled = output->crc_enabled;

Aside from the implicit bool -> int cast, I don't think you need this local var,
just use output->crc_enabled directly below.

>  	ret = drm_crtc_handle_vblank(crtc);
>  	if (!ret)
>  		DRM_ERROR("vkms failure on handling vblank");

This would be more useful with the error code printed.

>  
> +	if (state && crc_enabled) {
> +		state->n_frame = drm_crtc_accurate_vblank_count(crtc);
> +		queue_work(output->crc_workq, &state->crc_work);
> +	}
> +
> +	spin_unlock(&output->lock);
> +}
> +
> +static enum hrtimer_restart vkms_vblank_simulate(struct hrtimer *timer)
> +{
> +	struct vkms_output *output = container_of(timer, struct vkms_output,
> +						  vblank_hrtimer);
> +	int ret_overrun;
> +
> +	_vblank_handle(output);
> +
>  	ret_overrun = hrtimer_forward_now(&output->vblank_hrtimer,
>  					  output->period_ns);
>  
> @@ -97,6 +115,8 @@ vkms_atomic_crtc_duplicate_state(struct drm_crtc *crtc)
>  
>  	__drm_atomic_helper_crtc_duplicate_state(crtc, &vkms_state->base);
>  
> +	INIT_WORK(&vkms_state->crc_work, vkms_crc_work_handle);
> +
>  	return &vkms_state->base;
>  }
>  
> @@ -104,11 +124,18 @@ static void vkms_atomic_crtc_destroy_state(struct drm_crtc *crtc,
>  					   struct drm_crtc_state *state)
>  {
>  	struct vkms_crtc_state *vkms_state;
> +	struct vkms_output *vkms_out = drm_crtc_to_vkms_output(crtc);
>  
>  	vkms_state = to_vkms_crtc_state(state);
>  
>  	__drm_atomic_helper_crtc_destroy_state(state);
> -	kfree(vkms_state);
> +
> +	if (vkms_state) {
> +		flush_workqueue(vkms_out->crc_workq);

I'm a little worried about this bit. Since the workqueue is per-output, is it
possible you'll be waiting for more frames to complete than you need to be?

> +		drm_framebuffer_put(&vkms_state->data.fb);
> +		memset(&vkms_state->data, 0, sizeof(struct vkms_crc_data));
> +		kfree(vkms_state);
> +	}
>  }
>  
>  static const struct drm_crtc_funcs vkms_crtc_funcs = {
> @@ -120,6 +147,7 @@ static const struct drm_crtc_funcs vkms_crtc_funcs = {
>  	.atomic_destroy_state   = vkms_atomic_crtc_destroy_state,
>  	.enable_vblank		= vkms_enable_vblank,
>  	.disable_vblank		= vkms_disable_vblank,
> +	.set_crc_source		= vkms_set_crc_source,
>  };
>  
>  static void vkms_crtc_atomic_enable(struct drm_crtc *crtc,
> @@ -134,26 +162,37 @@ static void vkms_crtc_atomic_disable(struct drm_crtc *crtc,
>  	drm_crtc_vblank_off(crtc);
>  }
>  
> +static void vkms_crtc_atomic_begin(struct drm_crtc *crtc,
> +				   struct drm_crtc_state *old_crtc_state)
> +{
> +	struct vkms_output *vkms_output = drm_crtc_to_vkms_output(crtc);
> +
> +	spin_lock_irq(&vkms_output->lock);

Hmm, you can't lock across atomic_begin/flush. What is this protecting against?

> +}
> +
>  static void vkms_crtc_atomic_flush(struct drm_crtc *crtc,
>  				   struct drm_crtc_state *old_crtc_state)
>  {
> -	unsigned long flags;
> +	struct vkms_output *vkms_output = drm_crtc_to_vkms_output(crtc);
>  
>  	if (crtc->state->event) {
> -		spin_lock_irqsave(&crtc->dev->event_lock, flags);
> +		spin_lock(&crtc->dev->event_lock);

What's the rationale behind this change?

>  
>  		if (drm_crtc_vblank_get(crtc) != 0)
>  			drm_crtc_send_vblank_event(crtc, crtc->state->event);
>  		else
>  			drm_crtc_arm_vblank_event(crtc, crtc->state->event);
>  
> -		spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
> +		spin_unlock(&crtc->dev->event_lock);
>  
>  		crtc->state->event = NULL;
>  	}
> +
> +	spin_unlock_irq(&vkms_output->lock);
>  }
>  
>  static const struct drm_crtc_helper_funcs vkms_crtc_helper_funcs = {
> +	.atomic_begin	= vkms_crtc_atomic_begin,
>  	.atomic_flush	= vkms_crtc_atomic_flush,
>  	.atomic_enable	= vkms_crtc_atomic_enable,
>  	.atomic_disable	= vkms_crtc_atomic_disable,
> @@ -162,6 +201,7 @@ static const struct drm_crtc_helper_funcs vkms_crtc_helper_funcs = {
>  int vkms_crtc_init(struct drm_device *dev, struct drm_crtc *crtc,
>  		   struct drm_plane *primary, struct drm_plane *cursor)
>  {
> +	struct vkms_output *vkms_out = drm_crtc_to_vkms_output(crtc);
>  	int ret;
>  
>  	ret = drm_crtc_init_with_planes(dev, crtc, primary, cursor,
> @@ -173,5 +213,9 @@ int vkms_crtc_init(struct drm_device *dev, struct drm_crtc *crtc,
>  
>  	drm_crtc_helper_add(crtc, &vkms_crtc_helper_funcs);
>  
> +	spin_lock_init(&vkms_out->lock);
> +
> +	vkms_out->crc_workq = alloc_ordered_workqueue("vkms_crc_workq", 0);
> +
>  	return ret;
>  }
> diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
> index 37aa2ef33b21..5d78bd97e69c 100644
> --- a/drivers/gpu/drm/vkms/vkms_drv.c
> +++ b/drivers/gpu/drm/vkms/vkms_drv.c
> @@ -46,6 +46,7 @@ static void vkms_release(struct drm_device *dev)
>  	platform_device_unregister(vkms->platform);
>  	drm_mode_config_cleanup(&vkms->drm);
>  	drm_dev_fini(&vkms->drm);
> +	destroy_workqueue(vkms->output.crc_workq);
>  }
>  
>  static struct drm_driver vkms_driver = {
> diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
> index bf811d0ec349..95985649768c 100644
> --- a/drivers/gpu/drm/vkms/vkms_drv.h
> +++ b/drivers/gpu/drm/vkms/vkms_drv.h
> @@ -20,12 +20,23 @@ static const u32 vkms_formats[] = {
>  	DRM_FORMAT_XRGB8888,
>  };
>  
> +struct vkms_crc_data {
> +	struct drm_rect src;
> +	struct drm_framebuffer fb;
> +};
> +
>  /**
>   * vkms_crtc_state - Driver specific CRTC state
>   * @base: base CRTC state
> + * @crc_work: work struct to compute and add CRC entries
> + * @data: data required for CRC computation
> + * @n_frame: frame number for computed CRC
>   */
>  struct vkms_crtc_state {
>  	struct drm_crtc_state base;
> +	struct work_struct crc_work;
> +	struct vkms_crc_data data;
> +	unsigned int n_frame;
>  };
>  
>  struct vkms_output {
> @@ -35,6 +46,11 @@ struct vkms_output {
>  	struct hrtimer vblank_hrtimer;
>  	ktime_t period_ns;
>  	struct drm_pending_vblank_event *event;
> +	bool crc_enabled;

Where is this set to true?

> +	/* ordered wq for crc_work */
> +	struct workqueue_struct *crc_workq;
> +	/* protects concurrent access to crc_data */
> +	spinlock_t lock;
>  };
>  
>  struct vkms_device {
> @@ -95,4 +111,9 @@ void *vkms_gem_vmap(struct drm_gem_object *obj);
>  
>  void vkms_gem_vunmap(struct drm_gem_object *obj);
>  
> +/* CRC Support */
> +int vkms_set_crc_source(struct drm_crtc *crtc, const char *src_name,
> +			size_t *values_cnt);
> +void vkms_crc_work_handle(struct work_struct *work);
> +
>  #endif /* _VKMS_DRV_H_ */
> diff --git a/drivers/gpu/drm/vkms/vkms_plane.c b/drivers/gpu/drm/vkms/vkms_plane.c
> index aaf7c35faed6..1e0ee8ca8bd6 100644
> --- a/drivers/gpu/drm/vkms/vkms_plane.c
> +++ b/drivers/gpu/drm/vkms/vkms_plane.c
> @@ -24,6 +24,16 @@ static const struct drm_plane_funcs vkms_plane_funcs = {
>  static void vkms_primary_plane_update(struct drm_plane *plane,
>  				      struct drm_plane_state *old_state)
>  {
> +	struct vkms_crtc_state *state;
> +
> +	if (!plane->state->crtc || !plane->state->fb)
> +		return;
> +
> +	state = to_vkms_crtc_state(plane->state->crtc->state);
> +	memcpy(&state->data.src, &plane->state->src, sizeof(struct drm_rect));
> +	memcpy(&state->data.fb, plane->state->fb,
> +	       sizeof(struct drm_framebuffer));
> +	drm_framebuffer_get(&state->data.fb);
>  }
>  
>  static int vkms_plane_atomic_check(struct drm_plane *plane,
> -- 
> 2.17.1
> 

-- 
Sean Paul, Software Engineer, Google / Chromium OS


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