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Wed, 08 Jul 2026 05:13:07 -0700 (PDT) Date: Wed, 8 Jul 2026 14:13:05 +0200 From: Gary Bisson To: Adam Thiede Cc: AngeloGioacchino Del Regno , Thorsten Leemhuis , CK Hu =?utf-8?B?KOiDoeS/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" Subject: Re: [PATCH] drm/mediatek: mtk_dsi: enable hs clock during pre-enable Message-ID: 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: 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