[PATCH v2 3/4] drm/imx: call drm_atomic_helper_commit_hw_done after drm_atomic_helper_wait_for_vblanks

[Daniel Vetter]

On Mon, Feb 27, 2017 at 02:14:57PM +0100, Philipp Zabel wrote:
> Disabling planes will consist of two steps as of the following patch.
> First, the DP is asked to stop at the next vblank, and then, after the
> vblank the associated IDMAC channel is idle and can be disabled.
> To avoid further commits being awoken out of their wait for dependencies
> too early, we should report commit_hw_done only after wait_for_vblanks.
> 
> Signed-off-by: Philipp Zabel <p.zabel at pengutronix.de>
> Reviewed-by: Lucas Stach <l.stach at pengutronix.de>
> ---
>  drivers/gpu/drm/imx/imx-drm-core.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/imx/imx-drm-core.c b/drivers/gpu/drm/imx/imx-drm-core.c
> index f562cb7964b08..1ed120c181724 100644
> --- a/drivers/gpu/drm/imx/imx-drm-core.c
> +++ b/drivers/gpu/drm/imx/imx-drm-core.c
> @@ -169,10 +169,10 @@ static void imx_drm_atomic_commit_tail(struct drm_atomic_state *state)
>  
>  	drm_atomic_helper_commit_modeset_enables(dev, state);
>  
> -	drm_atomic_helper_commit_hw_done(state);
> -
>  	drm_atomic_helper_wait_for_vblanks(dev, state);
>  
> +	drm_atomic_helper_commit_hw_done(state);

That gives you a pretty good chance of halfing your refresh rate for async
flips. At least if you're not super careful about things. Did you
double-check this?
-Daniel

> +
>  	drm_atomic_helper_cleanup_planes(dev, state);
>  }
>  
> -- 
> 2.11.0
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch