[PATCH v2 08/12] drm: bridge: samsung-dsim: Add atomic_check

[Andrzej Hajda]

On 04.05.2022 13:40, Jagan Teki wrote:
> Fixing up the mode flags is required in order to correlate the
> correct sync flags of the surrounding components in the chain
> to make sure the whole pipeline can work properly.
> 
> So, handle the mode flags via bridge, atomic_check.
> 
> v2:
> * none
> 
> v1:
> * fix mode flags in atomic_check instead of mode_fixup
> 
> Signed-off-by: Jagan Teki <jagan at amarulasolutions.com>
> ---
>   drivers/gpu/drm/bridge/samsung-dsim.c | 14 ++++++++++++++
>   1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c
> index b618e52d0ee3..bd78cef890e4 100644
> --- a/drivers/gpu/drm/bridge/samsung-dsim.c
> +++ b/drivers/gpu/drm/bridge/samsung-dsim.c
> @@ -1340,6 +1340,19 @@ static void samsung_dsim_atomic_post_disable(struct drm_bridge *bridge,
>   	pm_runtime_put_sync(dsi->dev);
>   }
>   
> +static int samsung_dsim_atomic_check(struct drm_bridge *bridge,
> +				     struct drm_bridge_state *bridge_state,
> +				     struct drm_crtc_state *crtc_state,
> +				     struct drm_connector_state *conn_state)
> +{
> +	struct drm_display_mode *adjusted_mode = &crtc_state->adjusted_mode;
> +
> +	adjusted_mode->flags |= (DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC);
> +	adjusted_mode->flags &= ~(DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC);


1. Shouldn't this be in mode_fixup callback?
2. Where this requirement comes from? As Marek says it breaks Samsung 
platforms and is against DSIM specification[1]:

"45.2.2.1.2 RGB Interface
Vsync, Hsync, and VDEN are active high signals"

[1]: 
https://chasinglulu.github.io/downloads/SEC_Exynos4412_Users%20Manual_Ver.1.00.00.pdf

Regards
Andrzej



> +
> +	return 0;
> +}
> +
>   static void samsung_dsim_mode_set(struct drm_bridge *bridge,
>   				  const struct drm_display_mode *mode,
>   				  const struct drm_display_mode *adjusted_mode)
> @@ -1361,6 +1374,7 @@ static const struct drm_bridge_funcs samsung_dsim_bridge_funcs = {
>   	.atomic_duplicate_state		= drm_atomic_helper_bridge_duplicate_state,
>   	.atomic_destroy_state		= drm_atomic_helper_bridge_destroy_state,
>   	.atomic_reset			= drm_atomic_helper_bridge_reset,
> +	.atomic_check			= samsung_dsim_atomic_check,
>   	.atomic_pre_enable		= samsung_dsim_atomic_pre_enable,
>   	.atomic_enable			= samsung_dsim_atomic_enable,
>   	.atomic_disable			= samsung_dsim_atomic_disable,