[Intel-gfx] [PATCH 1/3] drm/atomic: Use explicit old crtc state in drm_atomic_add_affected_planes()

[Daniel Vetter]

On Thu, Nov 01, 2018 at 08:46:44PM +0200, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Replace 'crtc->state' with the explicit old crtc state.
> 
> Actually it shouldn't matter whether we use the old or the new
> crtc state here since any plane that has been removed from the
> crtc since the crtc state was duplicated will have been added
> to the atomic state already. That is, you can't call
> drm_atomic_set_crtc_for_plane() without having the new
> plane state already in hand.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

I think this will break amdgpu_notify_freesync because that doesn't grab
the crtc state first. Which worked with the old stuff, because adding a
connector or plane will also add it's crtc. But with the new logic we'll
just oops I think.

Otoh, it's dead code, so what exactly are amd people doing again :-)

Adding Harry so he's aware, but patch here looks good.

Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> ---
>  drivers/gpu/drm/drm_atomic.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> index 3dbfbddae7e6..064c48075917 100644
> --- a/drivers/gpu/drm/drm_atomic.c
> +++ b/drivers/gpu/drm/drm_atomic.c
> @@ -927,6 +927,8 @@ int
>  drm_atomic_add_affected_planes(struct drm_atomic_state *state,
>  			       struct drm_crtc *crtc)
>  {
> +	const struct drm_crtc_state *old_crtc_state =
> +		drm_atomic_get_old_crtc_state(state, crtc);
>  	struct drm_plane *plane;
>  
>  	WARN_ON(!drm_atomic_get_new_crtc_state(state, crtc));
> @@ -934,7 +936,7 @@ drm_atomic_add_affected_planes(struct drm_atomic_state *state,
>  	DRM_DEBUG_ATOMIC("Adding all current planes for [CRTC:%d:%s] to %p\n",
>  			 crtc->base.id, crtc->name, state);
>  
> -	drm_for_each_plane_mask(plane, state->dev, crtc->state->plane_mask) {
> +	drm_for_each_plane_mask(plane, state->dev, old_crtc_state->plane_mask) {
>  		struct drm_plane_state *plane_state =
>  			drm_atomic_get_plane_state(state, plane);
>  
> -- 
> 2.18.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch