Re: [PATCH 1/2] drm/fb_cma_helper: Add drm_fb_cma_setup_fence() helper

[Lucas Stach <l.stach@pengutronix.de>]

Hi Marek,

Am Montag, den 26.09.2016, 15:01 +0200 schrieb Marek Vasut:
> Add new drm_fb_cma_setup_fence() helper function extracted from the
> imx-drm driver. This function checks if the plane has DMABUF attached
> to it and if so, sets up the fence on which the atomic helper can wait.
> 
> Signed-off-by: Marek Vasut <marex@denx.de>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Lucas Stach <l.stach@pengutronix.de>
> ---
>  drivers/gpu/drm/drm_fb_cma_helper.c | 26 ++++++++++++++++++++++++++
>  include/drm/drm_fb_cma_helper.h     |  3 +++
>  2 files changed, 29 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_fb_cma_helper.c b/drivers/gpu/drm/drm_fb_cma_helper.c
> index 1fd6eac..2441707 100644
> --- a/drivers/gpu/drm/drm_fb_cma_helper.c
> +++ b/drivers/gpu/drm/drm_fb_cma_helper.c
> @@ -23,8 +23,10 @@
>  #include <drm/drm_crtc_helper.h>
>  #include <drm/drm_gem_cma_helper.h>
>  #include <drm/drm_fb_cma_helper.h>
> +#include <linux/dma-buf.h>
>  #include <linux/dma-mapping.h>
>  #include <linux/module.h>
> +#include <linux/reservation.h>
>  
>  #define DEFAULT_FBDEFIO_DELAY_MS 50
>  
> @@ -265,6 +267,30 @@ struct drm_gem_cma_object *drm_fb_cma_get_gem_obj(struct drm_framebuffer *fb,
>  }
>  EXPORT_SYMBOL_GPL(drm_fb_cma_get_gem_obj);
>  
> +/**
> + * drm_fb_cma_setup_fence() - Set up the fence for atomic helper to wait on

I don't really like the naming of the helper. It's not setting up any
fence, it's either extracting it from the plane and/or attaching it to
the planestate, so I would have expected the name to include extract or
attach.

> + * @plane: Which plane
> + * @state: Plane state to check

s/check/attach fence to

> + *
> + * If the plane fb has an dma-buf attached, fish out the exclusive
> + * fence for the atomic helper to wait on.
> + */
> +void drm_fb_cma_setup_fence(struct drm_plane *plane,
> +			    struct drm_plane_state *state)
> +{
> +	struct dma_buf *dma_buf;
> +
> +	if ((plane->state->fb == state->fb) || !state->fb)
> +		return;
> +
> +	dma_buf = drm_fb_cma_get_gem_obj(state->fb, 0)->base.dma_buf;
> +	if (!dma_buf)
> +		return;
> +
> +	state->fence = reservation_object_get_excl_rcu(dma_buf->resv);
> +}
> +EXPORT_SYMBOL_GPL(drm_fb_cma_setup_fence);
> +
>  #ifdef CONFIG_DEBUG_FS
>  static void drm_fb_cma_describe(struct drm_framebuffer *fb, struct seq_file *m)
>  {
> diff --git a/include/drm/drm_fb_cma_helper.h b/include/drm/drm_fb_cma_helper.h
> index f313211..fc122d3 100644
> --- a/include/drm/drm_fb_cma_helper.h
> +++ b/include/drm/drm_fb_cma_helper.h
> @@ -41,6 +41,9 @@ struct drm_framebuffer *drm_fb_cma_create(struct drm_device *dev,
>  struct drm_gem_cma_object *drm_fb_cma_get_gem_obj(struct drm_framebuffer *fb,
>  	unsigned int plane);
>  
> +void drm_fb_cma_setup_fence(struct drm_plane *plane,
> +			    struct drm_plane_state *state);
> +
>  #ifdef CONFIG_DEBUG_FS
>  struct seq_file;
>  


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