[PATCH v9 03/18] drm: exynos: dsi: Restore proper bridge chain order

[Marek Szyprowski]

On 09.12.2022 16:23, Jagan Teki wrote:
> From: Marek Szyprowski <m.szyprowski at samsung.com>
>
> Restore the proper bridge chain by finding the previous bridge
> in the chain instead of passing NULL.
>
> This establishes a proper bridge chain while attaching downstream
> bridges.
>
> v9, v4:
> * none
>
> v3:
> * new patch
>
> Signed-off-by: Marek Szyprowski <m.szyprowski at samsung.com>
> Signed-off-by: Jagan Teki <jagan at amarulasolutions.com>
> ---

As we are resurrecting this patch, one more change is needed here:

diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c 
b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
index e5b1540c4ae4..9d10a89d28f1 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
@@ -1713,6 +1713,7 @@ static int exynos_dsi_probe(struct platform_device 
*pdev)
         dsi->bridge.funcs = &exynos_dsi_bridge_funcs;
         dsi->bridge.of_node = dev->of_node;
         dsi->bridge.type = DRM_MODE_CONNECTOR_DSI;
+       dsi->bridge.pre_enable_prev_first = true;

         ret = component_add(dev, &exynos_dsi_component_ops);
         if (ret)


On Exynos5433 Exynos DSI is together with Exynos MIC in the bridge 
chain: Decon -> MIC -> DSI -> Panel.

To ensure proper order of initialization we need to mark our bridge 
driver also with the pre_enable_prev_first flag. This would also need to 
be added to patch "[PATCH v9 06/18] drm: bridge: Generalize Exynos-DSI 
driver into a Samsung DSIM bridge".


>   drivers/gpu/drm/exynos/exynos_drm_dsi.c | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> index ec673223d6b7..e5b1540c4ae4 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> @@ -1428,7 +1428,8 @@ static int exynos_dsi_attach(struct drm_bridge *bridge,
>   {
>   	struct exynos_dsi *dsi = bridge_to_dsi(bridge);
>   
> -	return drm_bridge_attach(bridge->encoder, dsi->out_bridge, NULL, flags);
> +	return drm_bridge_attach(bridge->encoder, dsi->out_bridge, bridge,
> +				 flags);
>   }
>   
>   static const struct drm_bridge_funcs exynos_dsi_bridge_funcs = {
> @@ -1474,7 +1475,10 @@ static int exynos_dsi_host_attach(struct mipi_dsi_host *host,
>   
>   	drm_bridge_add(&dsi->bridge);
>   
> -	drm_bridge_attach(encoder, &dsi->bridge, NULL, 0);
> +	drm_bridge_attach(encoder, &dsi->bridge,
> +			  list_first_entry_or_null(&encoder->bridge_chain,
> +						   struct drm_bridge,
> +						   chain_node), 0);
>   
>   	/*
>   	 * This is a temporary solution and should be made by more generic way.

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