[Letux-kernel] [PATCH 8/8] drm/ingenic: Attach bridge chain to encoders

[H. Nikolaus Schaller]

> Am 28.08.2021 um 21:09 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
> 
> Hi Paul,
> 
>> Am 10.08.2021 um 23:15 schrieb Paul Boddie <paul at boddie.org.uk>:
>> 
>> On Tuesday, 10 August 2021 09:52:36 CEST Paul Cercueil wrote:
>>> 
>>> Le mar., août 10 2021 at 01:17:20 +0200, Paul Boddie <paul at boddie.org.uk> a 
>> écrit :
>>>> 
>>>> But then the reported error occurs in the DRM driver:
>>>> 
>>>> ingenic-drm 13050000.lcdc0: Unable to init connector
>>>> ingenic-drm: probe of 13050000.lcdc0 failed with error -22
>>>> 
>>>> This originates in a call to drm_bridge_connector_init from
>>>> ingenic_drm_bind:
>>>> 
>>>> connector = drm_bridge_connector_init(drm, encoder);
>>>> 
>>>> The invoked function iterates over the registered bridges, one of
>>>> which seems to be the HDMI peripheral (it has bridge operations defined
>>>> identically to those specified in the Synopsys driver), but the type
>>>> member of the drm_bridge structure is set to 0
>>>> (DRM_MODE_CONNECTOR_Unknown).
>> 
>> Although I had fancy ideas about finding the connector node in the device tree 
>> and populating the necessary type details on the bridge, I decided to just add 
>> the following to the Synopsys driver's dw_hdmi_probe function:
>> 
>> hdmi->bridge.type = DRM_MODE_CONNECTOR_HDMIA;
>> 
>> This then lets the above invocation succeed and the Ingenic DRM driver 
>> initialises. However, I get "Input Not Supported" on my display.
> 
> Finally I am back to testing (on top of 5.14-rc7 now) and can confirm the
> symptoms and that this line above has a visible influence: I get a green screen.
> 
> This seems to indicate that the lcdc is scanning and the hdmi driver core is working.
> 
> And there are many drm commit timeouts:
> 
> [  390.947342] [drm:drm_crtc_commit_wait [drm]] *ERROR* flip_done timed out
> [  390.948018] [drm:drm_atomic_helper_wait_for_dependencies [drm_kms_helper]] *ERROR* [CRTC:32:crtc-0] commit wait timed out
> [  401.187362] [drm:drm_crtc_commit_wait [drm]] *ERROR* flip_done timed out
> [  401.188023] [drm:drm_atomic_helper_wait_for_dependencies [drm_kms_helper]] *ERROR* [CONNECTOR:35:HDMI-A-1] commit wait timed out
> [  411.427371] [drm:drm_crtc_commit_wait [drm]] *ERROR* flip_done timed out
> [  411.428029] [drm:drm_atomic_helper_wait_for_dependencies [drm_kms_helper]] *ERROR* [PLANE:31:plane-0] commit wait timed out
> [  411.537372] ------------[ cut here ]------------
> 
> Most likely it has something to do with the extended DMA descriptors which I also
> had modified as suggested by review.
> 
> I tried to fix like Paul C. suggested but with no success. The list of bridge
> drivers seems to be empty when calling of_drm_find_bridge() in dw_hdmi_probe().

Here is what Paul C. did write:

From what I understand the last bridge in the chained list is supposed to set the connector type. The HDMI driver's probe function should get a pointer to the next bridge in the queue and attach it (see how ite-it66121.c does it). The last bridge in the queue should be "hdmi-connector" (display-connector.c) which will effectively set the connector type.

> So the dw-hdmi driver does not find the connector.
> 
> The code (fragment) is
> 
> 	ep = of_graph_get_remote_node(dev->of_node, 1, -1);
> 	if (!ep)
> 			return ERR_PTR(-EPROBE_DEFER);
> 
> 	hdmi->next_bridge = of_drm_find_bridge(ep);
> 	of_node_put(ep);
> 
> but hdmi->next_bridge == NULL.
> 
> So we have to solve two separate issues:
> a) no video data (descriptors?)

Hm. Must be something else since upstream-jz4780-hdmi-v3 ([PATCH v3 0/9] MIPS: JZ4780 and CI20 HDMI) already included all these changes and was working!

> b) no correct setup of hdmi->bridge.type

Maybe both are the same issue, i.e. with Paul C's patches the setup is incomplete.

> 
> But wait - I think I still have to rebase things to v2 of the series of Paul C.

Done - makes no difference.

Next was to check lcdc setup

a) with new code (upstream-jz4780-hdmi-v4)

./jzlcdc
0x13050000 12f00000 JZ_REG_LCD_CFG
0x13050004 00000003 JZ_REG_LCD_VSYNC
0x13050008 0000000d JZ_REG_LCD_HSYNC
0x1305000c 0520026e JZ_REG_LCD_VAT
0x13050010 011b051b JZ_REG_LCD_DAH
0x13050014 0014026c JZ_REG_LCD_DAV
0x13050018 00000000 JZ_REG_LCD_PS
0x1305001c 00000000 JZ_REG_LCD_CLS
0x13050020 00000000 JZ_REG_LCD_SPL
0x13050024 00000000 JZ_REG_LCD_REV
0x13050030 24002008 JZ_REG_LCD_CTRL
0x13050034 00000004 JZ_REG_LCD_STATE
0x13050038 00000000 JZ_REG_LCD_IID
0x13050040 0559e000 JZ_REG_LCD_DA0
0x13050044 00000000 JZ_REG_LCD_SA0
0x13050048 000000f0 JZ_REG_LCD_FID0
0x1305004c 00000000 JZ_REG_LCD_CMD0
0x13050050 0559e010 JZ_REG_LCD_DA1
0x13050054 01000000 JZ_REG_LCD_SA1
0x13050058 000000f1 JZ_REG_LCD_FID1
0x1305005c 40096000 JZ_REG_LCD_CMD1

b) with old code (upstream-jz4780-hdmi-v3 - how good that I am running an archive of old branch versions - editing history is bad practise but required for linux development :)

0x13050000 12f00040 JZ_REG_LCD_CFG
0x13050004 00000003 JZ_REG_LCD_VSYNC
0x13050008 0000000d JZ_REG_LCD_HSYNC
0x1305000c 0520026e JZ_REG_LCD_VAT
0x13050010 011b051b JZ_REG_LCD_DAH
0x13050014 0014026c JZ_REG_LCD_DAV
0x13050018 00000000 JZ_REG_LCD_PS
0x1305001c 00000000 JZ_REG_LCD_CLS
0x13050020 00000000 JZ_REG_LCD_SPL
0x13050024 00000000 JZ_REG_LCD_REV
0x13050030 24000008 JZ_REG_LCD_CTRL
0x13050034 00000026 JZ_REG_LCD_STATE
0x13050038 000000f0 JZ_REG_LCD_IID
0x13050040 05353000 JZ_REG_LCD_DA0
0x13050044 00000000 JZ_REG_LCD_SA0
0x13050048 000000f0 JZ_REG_LCD_FID0
0x1305004c 00000000 JZ_REG_LCD_CMD0
0x13050050 05353010 JZ_REG_LCD_DA1
0x13050054 01300000 JZ_REG_LCD_SA1
0x13050058 000000f1 JZ_REG_LCD_FID1
0x1305005c 44096000 JZ_REG_LCD_CMD1

Well, there are minor diffs to be analysed...

BR,
Nikolaus