[PATCH] drm/mediatek: mtk_dsi: enable hs clock during pre-enable

[Thorsten Leemhuis]

On 7/7/26 04:20, CK Hu (胡俊光) wrote:
> On Mon, 2026-07-06 at 12:16 +0200, Thorsten Leemhuis wrote:
>> On 6/22/26 15:23, Adam Thiede wrote:
>> > On 6/22/26 06:22, Gary Bisson wrote:
>> > > On Thu, Jun 18, 2026 at 04:06:28PM -0500, Adam Thiede wrote:
>> > > > On 1/20/26 05:36, Gary Bisson wrote:
>> > > > > Some bridges, such as the TI SN65DSI83, require the HS clock to be
>> > > > > running in order to lock its PLL during its own pre-enable function.
>> > > > > 
>> > > > > Without this change, the bridge gives the following error:
>> > > > > sn65dsi83 14-002c: failed to lock PLL, ret=-110
>> > > > > sn65dsi83 14-002c: Unexpected link status 0x01
>> > > > > sn65dsi83 14-002c: reset the pipe
>> > > > > [...]
>> > > > 
>> > > > This commit was part of 7.1 and caused a problem for me.
>> > > > I'm running postmarketOS (basically Alpine Linux) on a Lenovo C330
>> > > > chromebook with a Mediatek MT8173 processor.
>> > > > The problem: when the display on my laptop powers off (via suspend or
>> > > > idle,
>> > > > like xset dpms off) the picture does not come back when the display
>> > > > powers
>> > > > back on (from resume). The display backlight comes on and brightness is
>> > > > adjustable but there is no picture. The only fix is to reboot.
>> > > > 
>> > > > Reverting this commit and applying it as a patch on top of 7.1
>> > > > addresses the
>> > > > issue for me.
>> > > > 
>> > > > You can view the config I'm using here:
>> > > > https://urldefense.com/v3/__https://gitlab.postmarketos.org/postmarketOS/pmaports/-/__;!!CTRNKA9wMg0ARbw!jrsPDtSEUdaINzLlq92Li8gmsEBkTOxZ6WUzNHjvIN6CyOJjHiHkNSOhIRPXFTLPlaYlxU2uvryVkwjUAN9bmax5$
>> > > > merge_requests/8819
>> > > > 
>> > > > Is there any sort of testing or other debugging info I can provide to
>> > > > help
>> > > > address this issue?
>> > > 
>> > > Thanks for reporting the issue, could you share some logs? Is the driver
>> > > saying anything during resume? Also, what type of panel is used on that
>> > > chromebook?
>> > 
>> > The curious thing is that there are no real logs in dmesg or /var/log/
>> > messages about this. This picture just fails to come back. If there are
>> > some kernel params I can set to get deeper logging, that would help, but
>> > I'm not aware of any.
>> > 
>> > I think the panel is a "BOE NV116WHM-T00" - I used this command to get
>> > info: cat /sys/class/drm/card0-eDP-1/edid | edid-decode
>> > 
>> > Output: https://urldefense.com/v3/__https://termbin.com/8nbd__;!!CTRNKA9wMg0ARbw!jrsPDtSEUdaINzLlq92Li8gmsEBkTOxZ6WUzNHjvIN6CyOJjHiHkNSOhIRPXFTLPlaYlxU2uvryVkwjUAJooSyqL$
>> 
>> This looked stalled. If I'm mistaken here, please let me known; but if
>> no solution is in sight, should we maybe just revert the change until a
>> proper was found?
> 
> It's welcome anyone to provide a revert patch,
> but I would still wait for the fixup patch until 7.2-rc4.
> If no fixup patch exist, then apply the revert patch.
>From my understanding of things the position in the devel cycle doesn't
matter much in a case like this. To quote Linus statements from
https://www.kernel.org/doc/html/latest/process/handling-regressions.html#on-how-quickly-regressions-should-be-fixed

"""
>From 2026-01-22:

 But a user complaining should basically result in an immediate fix -
 possibly a "revert and rethink".

With a later clarification on 2026-01-28:

 It's also worth noting that "immediate" obviously doesn't mean "right
 this *second* when the problem has been reported".

 But if it's a regression with a known commit that caused it, I think
 the rule of thumb should generally be "within a week", preferably
 before the next rc.
"""

Adam reported the problem about three weeks ago, so we are way past the
"rule of thumb" timeframe Linus set.

Ciao, Thorsten