Re: [PATCH v2] drm/msm/dp: remove fail safe mode related code

From: Abhinav Kumar
Date: Tue Apr 26 2022 - 13:36:56 EST

On 4/25/2022 11:00 PM, Stephen Boyd wrote:
Quoting Kuogee Hsieh (2022-04-25 22:56:35)
Current DP driver implementation has adding safe mode done at
dp_hpd_plug_handle() which is expected to be executed under event
thread context.

However there is possible circular locking happen (see blow stack trace)
after edp driver call dp_hpd_plug_handle() from dp_bridge_enable() which
is executed under drm_thread context.

After review all possibilities methods and as discussed on, supporting EDID
compliance tests in the driver is quite hacky. As seen with other
vendor drivers, supporting these will be much easier with IGT. Hence
removing all the related fail safe code for it so that no possibility
of circular lock will happen.

Changes in v2:
-- re text commit title
-- remove all fail safe mode

Signed-off-by: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>

Should add some Fixes tags here, probably for the first introduction of
this logic and the one that moved stuff around to try to avoid the
lockdep warning.

Fixes: 8b2c181 ("drm/msm/dp: add fail safe mode outside of event_mutex context")