Hi Boris,
On 16.12.2019 16:25, Boris Brezillon wrote:
> On Mon, 16 Dec 2019 16:02:36 +0100
> Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> wrote:
>> Hi Boris,
>>
>> On 16.12.2019 15:55, Boris Brezillon wrote:
>>> On Mon, 16 Dec 2019 14:54:25 +0100
>>> Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> 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@xxxxxxxxxxxxx>
>>>>> Reviewed-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
>>>>> Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
>>>> 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.
> Okay. Can you do a list_for_each_entry() on both encoder->bridge_chain
> and dsi->bridge_chain (dump bridge pointers in a pr_info()) before and
> after the list_splice_init() call?
encoder->bridge_chain contains only one element. dsi->drive_chain is empty.
Replacing that list_splice() with INIT_LIST_HEAD(&encoder->bridge_chain)
fixed the boot issue. It looks that this is related with the way the
Exynos DSI handles bridges (in bridge and out brige?). Maybe Andrzej
will give a bit more detailed comment and spread some light on this.
I can send a formal patch fixing this if You want.
>>> --->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
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