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Wed, 08 Jul 2026 14:12:29 +0200 (CEST) Message-ID: <956e84d2-728a-4e8c-8026-ae1a41e69171@collabora.com> Date: Wed, 8 Jul 2026 14:12:29 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] drm/mediatek: mtk_dsi: enable hs clock during pre-enable To: Adam Thiede , Thorsten Leemhuis , =?UTF-8?B?Q0sgSHUgKOiDoeS/iuWFiSk=?= , "bisson.gary@gmail.com" Cc: "chunkuang.hu@kernel.org" , "simona@ffwll.ch" , "dri-devel@lists.freedesktop.org" , "airlied@gmail.com" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "p.zabel@pengutronix.de" , "matthias.bgg@gmail.com" , "linux-mediatek@lists.infradead.org" , "regressions@lists.linux.dev" References: <20260120-mtkdsi-v1-1-b0f4094f3ac3@gmail.com> <42607fa4-485d-4142-b31c-7bfac71118d2@adamthiede.com> <5baeb90d2c3736df67ad075ede4ac765bfeaed2d.camel@mediatek.com> <84233951-ee22-4980-9f17-2af1df51fdbf@leemhuis.info> <6fed12a6-0c94-477f-8a2e-466c33ea2e29@collabora.com> From: AngeloGioacchino Del Regno Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 7/8/26 03:25, Adam Thiede wrote: > On 7/7/26 05:38, AngeloGioacchino Del Regno wrote: >> On 7/7/26 10:51, Thorsten Leemhuis wrote: >>> 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 >> >> This is a kind of odd situation here. The fix from Adam is actually correct, as in, >> the SN65DSI83 bridge gets broken without... >> >> ....but then, there's some more oddness going on: I tried to reproduce this on my >> MT8173 Elm device, but there I can resume the system just fine, and the display is >> up and running like normal? >> >> I'm not sure what to advice here at this point - just adding some info. >> >> Cheers, >> Angelo > Angelo, would you mind sharing your config, and the details of what you're running? > It might be a configuration difference. > Thanks! Sure, here it is: https://gitlab.collabora.com/mediatek/aiot/linux/-/blob/mediatek-dev/arch/arm64/configs/defconfig?ref_type=heads Cheers, Angelo