[PATCHv2 11/22] drm/bridge: tc358767: ensure DP is disabled before LT

[Tomi Valkeinen]

On 15/04/2019 11:49, Andrzej Hajda wrote:
> On 26.03.2019 11:31, Tomi Valkeinen wrote:
>> Link training will sometimes fail if the DP link is, for some whatever
>> reason, enabled when tc_main_link_enable() is called.
> 
> 
> Only tc_stream_enable enables it, does it mean that link training can
> happen after tc_stream_enable?
> 
> It suggests that driver/device preforms strange things, is it true? Or
> just overprotection?

Just protection. I did try all kinds of things when trying to get the
link setup stable and having DP0CTL enabled before link training was one
of the problems I encountered.

In theory DP0CTL should always be disabled when we call
tc_main_link_enable, but I thought it best leave it there in case we
accidentally leave DP0CTL enabled via some error path or such.

Maybe we should have a WARN there if DP0CTL is enabled (and then clear
it), so that we might find those error cases.

 Tomi

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