[1/2] drm: bridge: samsung-dsim: Initialize bridge on attach

[Marek Vasut]

On 6/24/24 11:26 AM, Alexander Stein wrote:

Hello Alexander,

> Am Montag, 13. Mai 2024, 04:16:27 CEST schrieb Marek Vasut:
>> Initialize the bridge on attach already, to force lanes into LP11
>> state, since attach does trigger attach of downstream bridges which
>> may trigger (e)DP AUX channel mode read.
>>
>> This fixes a corner case where DSIM with TC9595 attached to it fails
>> to operate the DP AUX channel, because the TC9595 enters some debug
>> mode when it is released from reset without lanes in LP11 mode. By
>> ensuring the DSIM lanes are in LP11, the TC9595 (tc358767.c driver)
>> can be reset in its attach callback called from DSIM attach callback,
>> and recovered out of the debug mode just before TC9595 performs first
>> AUX channel access later in its attach callback.
>>
>> Signed-off-by: Marek Vasut <marex at denx.de>
> 
> This does the trick on my hardware as well.
> Reviewed-by: Alexander Stein <alexander.stein at ew.tq-group.com>

Thank you. I still have to address your previous comment on 1/2, I 
didn't get to that one yet, sorry.

Also, I am not sure if this should be applied as-is, it is a borderline 
workaround and there was some discussion about fixing the LP11 lane mode 
switch properly. Michael ?