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

[H. Nikolaus Schaller]

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

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

BR,
Nikolaus