Re: [REGRESSION] "drm: convert drivers to use drm_of_find_panel_or_bridge" breaks graphics on hikey

From: Rob Herring
Date: Thu May 04 2017 - 18:43:03 EST

On Thu, May 4, 2017 at 5:33 PM, John Stultz <john.stultz@xxxxxxxxxx> wrote:
> Hey folks,
> Testing mainline with HiKey, I noticed graphics was no longer
> properly initializing. I don't seem to get much useful info in the way
> of errors, its just the kirin drm driver doesn't seem to
> initialize/bind.
> Digging through the recent changes I landed on ebc944613567 ("drm:
> convert drivers to use drm_of_find_panel_or_bridge"). And reverting
> that patch (which doesn't revert cleanly, but cleanly enough for me to
> test my device), seems to resolve the issue.
> I've not been able to root cause the problem, but I wanted to bring it
> up quickly here, as folks might figure out the error faster then I
> can.

Looking at the change to HiSilicon code:

- endpoint = of_graph_get_endpoint_by_regs(np, 1, -1);
+ ret = drm_of_find_panel_or_bridge(np, 0, 0, NULL, &dsi->bridge);

This should be (1,0) rather than (0,0) for (port,endpoint).