[PATCH] drm: Fix crtc color management when doing suspend/resume

[Maarten Lankhorst]

Op 23-08-18 om 17:11 schreef Alexandru Gheorghe:
> When doing suspend/resume drivers usually use the
> drm_atomic_helper_suspend/drm_atomic_helper_resume pair for saving the
> state and then re-comitting it.
>
> The problems is that drm_crtc_state has a bool field called
> color_mgmt_changed, which mali-dp and other drivers uses it to detect
> if coefficients need to be reprogrammed, but that never happens
> because the save state has color_mgmt_changed set to 0.
>
> Fix that by setting color_mgmt_changed to true if the crtc duplicated
> state differs from the reset state.
>
> Signed-off-by: Alexandru Gheorghe <alexandru-cosmin.gheorghe at arm.com>
> ---
>  drivers/gpu/drm/drm_atomic_helper.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> index 6dd5036545ec..e88aa62bc822 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -3196,8 +3196,13 @@ int drm_atomic_helper_commit_duplicated_state(struct drm_atomic_state *state,
>  	for_each_new_plane_in_state(state, plane, new_plane_state, i)
>  		state->planes[i].old_state = plane->state;
>  
> -	for_each_new_crtc_in_state(state, crtc, new_crtc_state, i)
> +	for_each_new_crtc_in_state(state, crtc, new_crtc_state, i) {
>  		state->crtcs[i].old_state = crtc->state;
> +		new_crtc_state->color_mgmt_changed =
> +			new_crtc_state->degamma_lut != crtc->state->degamma_lut ||
> +			new_crtc_state->ctm != crtc->state->ctm ||
> +			new_crtc_state->gamma_lut != crtc->state->gamma_lut;
Don't look at $obj->state please, use for_each_oldnew.

But it looks like we should set color_mgmt_changed in drm_atomic_helper_check_planes(),
(or check_modeset if we want to know color_mgmt_changed from the planes atomic_check() too.
The existing places that set color_mgmt_changed should be removed, because that check is now done in a single place. :)
>  	for_each_new_connector_in_state(state, connector, new_conn_state, i)
>  		state->connectors[i].old_state = connector->state;