[Intel-gfx] [PATCH 12/25] drm/rcar-du: Annotate dma-fence critical section in commit path

[Laurent Pinchart]

Hi Daniel,

Thank you for the patch.

On Tue, Jul 07, 2020 at 10:12:16PM +0200, Daniel Vetter wrote:
> Ends right after drm_atomic_helper_commit_hw_done(), absolutely
> nothing fancy going on here.

Just looking at this patch and the commit message, I have no idea what
this does, and why. It would be nice to expand the commit message to
give some more context, and especially explain why ending signalling
right after drm_atomic_helper_commit_hw_done() is the right option.

I suppose I'll have to check the whole series in the meantime :-)

> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> Cc: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> Cc: Kieran Bingham <kieran.bingham+renesas at ideasonboard.com>
> Cc: linux-renesas-soc at vger.kernel.org
> ---
>  drivers/gpu/drm/rcar-du/rcar_du_kms.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_kms.c b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> index 482329102f19..42c5dc588435 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> @@ -391,6 +391,7 @@ static void rcar_du_atomic_commit_tail(struct drm_atomic_state *old_state)
>  	struct drm_crtc_state *crtc_state;
>  	struct drm_crtc *crtc;
>  	unsigned int i;
> +	bool fence_cookie = dma_fence_begin_signalling();

Can this be moved right before the
drm_atomic_helper_commit_modeset_disables() call ?

>  
>  	/*
>  	 * Store RGB routing to DPAD0 and DPAD1, the hardware will be configured
> @@ -417,6 +418,7 @@ static void rcar_du_atomic_commit_tail(struct drm_atomic_state *old_state)
>  	drm_atomic_helper_commit_modeset_enables(dev, old_state);
>  
>  	drm_atomic_helper_commit_hw_done(old_state);
> +	dma_fence_end_signalling(fence_cookie);
>  	drm_atomic_helper_wait_for_flip_done(dev, old_state);
>  
>  	drm_atomic_helper_cleanup_planes(dev, old_state);

-- 
Regards,

Laurent Pinchart