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

[Marek Szyprowski <m.szyprowski@samsung.com>]

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@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);

Could you point why this change is needed? It breaks display on Samsung 
s6e8aa0 dsi panel (Trats and Trats2 boards) and tc358764 bridge (Arndale 
board). I have no detailed knowledge of the DSI protocol nor those 
panels/bridges. If there is something missing in the drivers for those 
panels/bridges, let me know.


> +	adjusted_mode->flags &= ~(DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC);
> +
> +	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,

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland