linux-kernel - Re: [PATCH 2/2] drm/bridge: ti-sn65dsi86: break probe dependency loop

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Message-ID: <20250902162246.4143785-1-john.ripple@keysight.com>
Date: Tue,  2 Sep 2025 10:22:46 -0600
From: John Ripple <john.ripple@...sight.com>
To: dianders@...omium.org
Cc: Laurent.pinchart@...asonboard.com, airlied@...il.com,
        andrzej.hajda@...el.com, dri-devel@...ts.freedesktop.org,
        jernej.skrabec@...il.com, john.ripple@...sight.com, jonas@...boo.se,
        linux-kernel@...r.kernel.org, maarten.lankhorst@...ux.intel.com,
        mripard@...nel.org, neil.armstrong@...aro.org, rfoss@...nel.org,
        simona@...ll.ch, tzimmermann@...e.de
Subject: Re: [PATCH 2/2] drm/bridge: ti-sn65dsi86: break probe dependency loop

Hi,

>Which i2c bridge are you talking about? You mean the one created by
>i2c_add_adapter() in drm_dp_aux_register()? I guess I'm confused about
>why the DSI probe routine would even be looking for that adapter.

The i2c bridge I was seeing was created by the drm_bridge_add() function
in the ti_sn_bridge_probe() function. Without moving the ti_sn_attach_host()
function out of the ti_sn_bridge_probe() function I kept getting stuck in a 
loop during boot where the bridge would never come up. It's possible this
could be a unique interaction with the hardware I'm using and the nwl-dsi
driver. 

>In any case, I don't _think_ your patch is valid. Specifically, if you
>notice ti_sn_attach_host() can return "-EPROBE_DEFER". That's a valid
>error code to return from a probe routine but I don't think it's a
>valid error code to return from a bridge attach function, is it?

What error code would you suggest?