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Wed, 08 Jul 2026 14:25:49 +0200 (CEST) Message-ID: Date: Wed, 8 Jul 2026 14:25:49 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] drm/mediatek: mtk_dsi: enable hs clock during pre-enable To: Gary Bisson , Adam Thiede Cc: Thorsten Leemhuis , =?UTF-8?B?Q0sgSHUgKOiDoeS/iuWFiSk=?= , "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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260708_052554_127178_8946CF95 X-CRM114-Status: GOOD ( 31.34 ) X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org On 7/8/26 14:13, Gary Bisson wrote: > Hi Adam, > > On Tue, Jul 07, 2026 at 08:25:41PM -0500, 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. > > As a FYI here is the latest branch I tested that patch on: > https://github.com/gibsson/linux-next/commits/master-mtk/ > > As far as I remember suspend/resume was ok. It was tested with a > Tungsten510 SMARC SOM (MT8370) + sn65dsi83 + tm070jdhg30 display. > Both the bridge and the display are mainline, you can see that the main > change is in the defconfig where a bunch of options are changed to be > built-in (for NFS booting). > > I'll try to repro against latest kernel this week and report back. > > In your case, is the panel upstream as well? > > Regards, > Gary Gary, thanks for chiming in. The machine he's referring to is using a Parade PS8640 DSI to eDP bridge: check mt8173-elm.dtsi for (slightly) more information. Cheers, Angelo