[PATCH v4 04/11] drm/bridge: Make the bridge chain a double-linked list

[Marek Szyprowski]

Hi Boris,

On 16.12.2019 15:55, Boris Brezillon wrote:
> On Mon, 16 Dec 2019 14:54:25 +0100
> Marek Szyprowski <m.szyprowski at samsung.com> wrote:
>> On 03.12.2019 15:15, Boris Brezillon wrote:
>>> So that each element in the chain can easily access its predecessor.
>>> This will be needed to support bus format negotiation between elements
>>> of the bridge chain.
>>>
>>> Signed-off-by: Boris Brezillon <boris.brezillon at collabora.com>
>>> Reviewed-by: Neil Armstrong <narmstrong at baylibre.com>
>>> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
>> I've noticed that this patch got merged to linux-next as commit
>> 05193dc38197021894b17239fafbd2eb1afe5a45. Sadly it breaks booting of
>> Samsung Exynos5250-based Arndale board. Booting stops after following
>> messages:
>>
>> [drm] Exynos DRM: using 14400000.fimd device for DMA mapping operations
>> exynos-drm exynos-drm: bound 14400000.fimd (ops fimd_component_ops)
>> exynos-drm exynos-drm: bound 14450000.mixer (ops mixer_component_ops)
>> exynos-drm exynos-drm: bound 14500000.dsi (ops exynos_dsi_component_ops)
>> exynos-drm exynos-drm: bound 14530000.hdmi (ops hdmi_component_ops)
>> [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
>> [drm] No driver support for vblank timestamp query.
>> [drm] Cannot find any crtc or sizes
>> [drm] Cannot find any crtc or sizes
>> [drm] Initialized exynos 1.1.0 20180330 for exynos-drm on minor 0
>>
>> I will try to debug this and provide more information soon.
>>
> Can you try with this diff applied?

This patch doesn't change anything.

> --->8---
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> index 3955f84dc893..118ecedc7621 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> @@ -1523,7 +1523,7 @@ static int exynos_dsi_host_attach(struct mipi_dsi_host *host,
>          if (out_bridge) {
>                  drm_bridge_attach(encoder, out_bridge, NULL);
>                  dsi->out_bridge = out_bridge;
> -               list_splice(&encoder->bridge_chain, &dsi->bridge_chain);
> +               list_splice_init(&encoder->bridge_chain, &dsi->bridge_chain);
>          } else {
>                  int ret = exynos_dsi_create_connector(encoder);
>   
> diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c
> index 6c5b80ad6154..e1378d48210f 100644
> --- a/drivers/gpu/drm/vc4/vc4_dsi.c
> +++ b/drivers/gpu/drm/vc4/vc4_dsi.c
> @@ -1613,7 +1613,7 @@ static int vc4_dsi_bind(struct device *dev, struct device *master, void *data)
>           * from our driver, since we need to sequence them within the
>           * encoder's enable/disable paths.
>           */
> -       list_splice(&dsi->encoder->bridge_chain, &dsi->bridge_chain);
> +       list_splice_init(&dsi->encoder->bridge_chain, &dsi->bridge_chain);
>   
>          if (dsi->port == 0)
>                  vc4_debugfs_add_regset32(drm, "dsi0_regs", &dsi->regset);
> @@ -1639,7 +1639,7 @@ static void vc4_dsi_unbind(struct device *dev, struct device *master,
>           * Restore the bridge_chain so the bridge detach procedure can happen
>           * normally.
>           */
> -       list_splice(&dsi->bridge_chain, &dsi->encoder->bridge_chain);
> +       list_splice_init(&dsi->bridge_chain, &dsi->encoder->bridge_chain);
>          vc4_dsi_encoder_destroy(dsi->encoder);
>   
>          if (dsi->port == 1)
>
>
Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland