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Message-ID: <825ff59f-0a97-49a1-a210-a7ee275364bc@rock-chips.com>
Date: Thu, 4 Sep 2025 11:19:05 +0800
From: Damon Ding <damon.ding@...k-chips.com>
To: Marek Szyprowski <m.szyprowski@...sung.com>, andrzej.hajda@...el.com,
neil.armstrong@...aro.org, rfoss@...nel.org
Cc: Laurent.pinchart@...asonboard.com, jonas@...boo.se,
jernej.skrabec@...il.com, maarten.lankhorst@...ux.intel.com,
mripard@...nel.org, tzimmermann@...e.de, airlied@...il.com, simona@...ll.ch,
jingoohan1@...il.com, inki.dae@...sung.com, sw0312.kim@...sung.com,
kyungmin.park@...sung.com, krzk@...nel.org, alim.akhtar@...sung.com,
hjc@...k-chips.com, heiko@...ech.de, andy.yan@...k-chips.com,
dmitry.baryshkov@....qualcomm.com, l.stach@...gutronix.de,
dianders@...omium.org, dri-devel@...ts.freedesktop.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-samsung-soc@...r.kernel.org, linux-rockchip@...ts.infradead.org
Subject: Re: [PATCH v4 00/13] Apply drm_bridge_connector and panel_bridge
helper for the Analogix DP driver
Hi Marek,
On 9/1/2025 6:25 PM, Marek Szyprowski wrote:
> On 01.09.2025 05:41, Damon Ding wrote:
>> On 8/29/2025 4:23 PM, Marek Szyprowski wrote:
>>> On 29.08.2025 10:08, Damon Ding wrote:
>>>> On 8/20/2025 5:20 AM, Marek Szyprowski wrote:
>>>>> On 15.08.2025 04:59, Damon Ding wrote:
>>>>>> On 2025/8/15 5:16, Marek Szyprowski wrote:
>>>>>>> On 14.08.2025 16:33, Marek Szyprowski wrote:
>>>>>>>> On 14.08.2025 12:47, Damon Ding wrote:
>>>>>>>>> PATCH 1 is a small format optimization for struct
>>>>>>>>> analogid_dp_device.
>>>>>>>>> PATCH 2 is to perform mode setting in
>>>>>>>>> &drm_bridge_funcs.atomic_enable.
>>>>>>>>> PATCH 3-6 are preparations for apply drm_bridge_connector helper.
>>>>>>>>> PATCH 7 is to apply the drm_bridge_connector helper.
>>>>>>>>> PATCH 8-10 are to move the panel/bridge parsing to the Analogix
>>>>>>>>> side.
>>>>>>>>> PATCH 11-12 are preparations for apply panel_bridge helper.
>>>>>>>>> PATCH 13 is to apply the panel_bridge helper.
>>>>>>>>
>>>>>>>> This series lacks 'select DRM_BRIDGE_CONNECTOR' in ExynosDP's
>>>>>>>> Kconfig,
>>>>>>>> so it causes build break:
>>>>>>>>
>>>>>>>> drivers/gpu/drm/exynos/exynos_dp.c:177: undefined reference to
>>>>>>>> `drm_bridge_connector_init'
>>>>>>>> make[2]: *** [scripts/Makefile.vmlinux:91: vmlinux] Error 1
>>>>>>>>
>>>>>>>> After adding this dependency, the Exynos DP driver stops
>>>>>>>> working. On
>>>>>>>> Samsung Snow Chromebook I observed following issue:
>>>>>>>>
>>>>>>>> [ 4.534220] exynos-dp 145b0000.dp-controller: failed to attach
>>>>>>>> following panel or bridge (-16)
>>>>>>>> [ 4.543428] exynos-drm exynos-drm: failed to bind
>>>>>>>> 145b0000.dp-controller (ops exynos_dp_ops): -16
>>>>>>>> [ 4.551775] exynos-drm exynos-drm: adev bind failed: -16
>>>>>>>> [ 4.556559] exynos-dp 145b0000.dp-controller: probe with driver
>>>>>>>> exynos-dp failed with error -16
>>>>>>>>
>>>>>>>> I will investigate details later in the evening.
>>>>>>>
>>>>>>> The failure is caused by trying to add plat_data->next_bridge twice
>>>>>>> (from exynos_dp's .attach callback, and from analogix' ->bind
>>>>>>> callback).
>>>>>>>
>>>>>>>
>>>>>>> Best regards
>>>>>>
>>>>>> I see. The bridge attachment for the next bridge was not well thought
>>>>>> out. It may be better to move panel_bridge addition a little forward
>>>>>> and remove next_bridge attachment on the Analogix side. Then, the
>>>>>> Rockchip side and Exynos side can do their own next_bridge attachment
>>>>>> in &analogix_dp_plat_data.attach() as they want.
>>>>>>
>>>>>> Could you please help test the following modifications(they have been
>>>>>> tested on my RK3588S EVB1 Board) on the Samsung Snow Chromebook? ;-)
>>>>>
>>>>> Assuming that I properly applied the malformed diff, it doesn't solve
>>>>> all the issues. There are no errors reported though, but the display
>>>>> chain doesn't work and no valid mode is reported:
>>>>>
>>>>> # dmesg | grep drm
>>>>> [ 3.384992] [drm] Initialized panfrost 1.4.0 for 11800000.gpu on
>>>>> minor 0
>>>>> [ 4.487739] [drm] Exynos DRM: using 14400000.fimd device for DMA
>>>>> mapping operations
>>>>> [ 4.494202] exynos-drm exynos-drm: bound 14400000.fimd (ops
>>>>> fimd_component_ops)
>>>>> [ 4.502374] exynos-drm exynos-drm: bound 14450000.mixer (ops
>>>>> mixer_component_ops)
>>>>> [ 4.511930] exynos-drm exynos-drm: bound 145b0000.dp-controller
>>>>> (ops
>>>>> exynos_dp_ops)
>>>>> [ 4.518411] exynos-drm exynos-drm: bound 14530000.hdmi (ops
>>>>> hdmi_component_ops)
>>>>> [ 4.529628] [drm] Initialized exynos 1.1.0 for exynos-drm on
>>>>> minor 1
>>>>> [ 4.657434] exynos-drm exynos-drm: [drm] Cannot find any crtc or
>>>>> sizes
>>>>> [ 4.925023] exynos-drm exynos-drm: [drm] Cannot find any crtc or
>>>>> sizes
>>>>>
>>>>> # ./modetest -c -Mexynos
>>>>> Connectors:
>>>>> id encoder status name size (mm) modes
>>>>> encoders
>>>>> 69 0 disconnected LVDS-1 0x0 0
>>>>> 68
>>>>> props:
>>>>> 1 EDID:
>>>>> flags: immutable blob
>>>>> blobs:
>>>>>
>>>>> value:
>>>>> 2 DPMS:
>>>>> flags: enum
>>>>> enums: On=0 Standby=1 Suspend=2 Off=3
>>>>> value: 0
>>>>> 5 link-status:
>>>>> flags: enum
>>>>> enums: Good=0 Bad=1
>>>>> value: 0
>>>>> 6 non-desktop:
>>>>> flags: immutable range
>>>>> values: 0 1
>>>>> value: 0
>>>>> 4 TILE:
>>>>> flags: immutable blob
>>>>> blobs:
>>>>>
>>>>> value:
>>>>> 71 0 disconnected HDMI-A-1 0x0 0
>>>>> 70
>>>>> props:
>>>>> 1 EDID:
>>>>> flags: immutable blob
>>>>> blobs:
>>>>>
>>>>> value:
>>>>> 2 DPMS:
>>>>> flags: enum
>>>>> enums: On=0 Standby=1 Suspend=2 Off=3
>>>>> value: 0
>>>>> 5 link-status:
>>>>> flags: enum
>>>>> enums: Good=0 Bad=1
>>>>> value: 0
>>>>> 6 non-desktop:
>>>>> flags: immutable range
>>>>> values: 0 1
>>>>> value: 0
>>>>> 4 TILE:
>>>>> flags: immutable blob
>>>>> blobs:
>>>>>
>>>>> value:
>>>>>
>>>>>
>>>>> I will investigate details later this week.
>>>>>
>>>>
>>>> Could you please provide the related DTS file for the test? I will
>>>> also try to find out the reason for this unexpected issue. ;-)
>>>
>>> Unfortunately I didn't find enough time to debug this further. The above
>>> log is from Samsung Snow Chromebook,
>>> arch/arm/boot/dts/samsung/exynos5250-snow.dts
>>>
>>>
>>
>> I compare the differences in the following display path before and
>> after this patch series:
>>
>> exynos_dp -> nxp-ptn3460 -> panel "auo,b116xw03"
>>
>> The issue is likely caused by the &drm_connector_funcs.detect()
>> related logic. Before this patch series, the nxp-ptn3460 connector is
>> always connector_status_connected because there is not available
>> &drm_connector_funcs.detect(). After it, the DRM_BRIDGE_OP_DETECT flag
>> make the connection status depend on analogix_dp_bridge_detect().
>>
>> Could you please add the following patches additionally and try again?
>> (Not the final solution, just validation)
>>
>> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> index a93ff8f0a468..355911c47354 100644
>> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> @@ -1491,9 +1491,11 @@ int analogix_dp_bind(struct analogix_dp_device
>> *dp, struct drm_device *drm_dev)
>> }
>> }
>>
>> - bridge->ops = DRM_BRIDGE_OP_DETECT |
>> - DRM_BRIDGE_OP_EDID |
>> + bridge->ops = DRM_BRIDGE_OP_EDID |
>> DRM_BRIDGE_OP_MODES;
>> + if (drm_bridge_is_panel(dp->plat_data->next_bridge))
>> + bridge->ops |= DRM_BRIDGE_OP_DETECT;
>> +
>> bridge->of_node = dp->dev->of_node;
>> bridge->type = DRM_MODE_CONNECTOR_eDP;
>> ret = devm_drm_bridge_add(dp->dev, &dp->bridge);
>
> It is better. Now the display panel is detected and reported to
> userspace, but it looks that something is not properly initialized,
> because there is garbage instead of the proper picture.
>
I simulated the display path mentioned above on my RK3588S EVB1 Board.
To my slight surprise, it displayed normally with the reported connector
type DRM_MODE_CONNECTOR_LVDS. ;-)
The modifications included:
1.Synchronized the Analogix DP ralated DT configurations with Samsung
Snow Chromebook.
2.Skipped the I2C transfers and GPIO operations in nxp-ptn3460 driver.
3.Set the EDID to that of eDP Panel LP079QX1-SP0V forcibly.
Additionally, I added debug logs to verify whether the functions in
ptn3460_bridge_funcs were actually called.
Did you encounter any unexpected logs during your investigation? I'd
like to perform additional tests on this issue. :-)
Best regards,
Damon
View attachment "simulation_for_ptn3460_20250904.patch" of type "text/plain" (5921 bytes)
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