Messages in this thread | | | Date | Sun, 8 Oct 2023 23:52:13 +0300 | Subject | Re: [PATCH] drm/panel: Move AUX B116XW03 out of panel-edp back to panel-simple | From | Anton Bambura <> |
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On 10/5/23 21:10, Doug Anderson wrote: > Hi, > > On Tue, Sep 26, 2023 at 7:01 AM Doug Anderson <dianders@chromium.org> wrote: >> Hi, >> >> On Tue, Sep 26, 2023 at 1:06 AM AngeloGioacchino Del Regno >> <angelogioacchino.delregno@collabora.com> wrote: >>> Il 26/09/23 00:00, Douglas Anderson ha scritto: >>>> In commit 5f04e7ce392d ("drm/panel-edp: Split eDP panels out of >>>> panel-simple") I moved a pile of panels out of panel-simple driver >>>> into the newly created panel-edp driver. One of those panels, however, >>>> shouldn't have been moved. >>>> >>>> As is clear from commit e35e305eff0f ("drm/panel: simple: Add AUO >>>> B116XW03 panel support"), AUX B116XW03 is an LVDS panel. It's used in >>>> exynos5250-snow and exynos5420-peach-pit where it's clear that the >>>> panel is hooked up with LVDS. Furthermore, searching for datasheets I >>>> found one that makes it clear that this panel is LVDS. >>>> >>>> As far as I can tell, I got confused because in commit 88d3457ceb82 >>>> ("drm/panel: auo,b116xw03: fix flash backlight when power on") Jitao >>>> Shi added "DRM_MODE_CONNECTOR_eDP". That seems wrong. Looking at the >>>> downstream ChromeOS trees, it seems like some Mediatek boards are >>>> using a panel that they call "auo,b116xw03" that's an eDP panel. The >>>> best I can guess is that they actually have a different panel that has >>>> similar timing. If so then the proper panel should be used or they >>>> should switch to the generic "edp-panel" compatible. >>>> >>>> When moving this back to panel-edp, I wasn't sure what to use for >>>> .bus_flags and .bus_format and whether to add the extra "enable" delay >>>> from commit 88d3457ceb82 ("drm/panel: auo,b116xw03: fix flash >>>> backlight when power on"). I've added formats/flags/delays based on my >>>> (inexpert) analysis of the datasheet. These are untested. >>>> >>>> NOTE: if/when this is backported to stable, we might run into some >>>> trouble. Specifically, before 474c162878ba ("arm64: dts: mt8183: >>>> jacuzzi: Move panel under aux-bus") this panel was used by >>>> "mt8183-kukui-jacuzzi", which assumed it was an eDP panel. I don't >>>> know what to suggest for that other than someone making up a bogus >>>> panel for jacuzzi that's just for the stable channel. >>>> >>>> Fixes: 88d3457ceb82 ("drm/panel: auo,b116xw03: fix flash backlight when power on") >>>> Fixes: 5f04e7ce392d ("drm/panel-edp: Split eDP panels out of panel-simple") >>>> Signed-off-by: Douglas Anderson <dianders@chromium.org> >>>> --- >>>> I haven't had a snow or peach-pit hooked up for debugging / testing >>>> for years. I presume that they must be broken and hope that this fixes >>>> them. >>> We could avoid backport breakages by avoiding to backport this to any kernel >>> that doesn't contain commit 474c162878ba ("arm64: dts: mt8183: jacuzzi: Move >>> panel under aux-bus")... because creating a dummy panel to get two wrongs >>> right is definitely not ok. >> Sure, except that leaves us with ... a breakage. :-P >> >> Although I haven't tested it, I have a hard time believing that >> exynos5250-snow and exynos5420-peach-pit will work properly with the >> panel defined as an eDP panel. That means that they will be broken. If >> someone cared to get those fixed in a stable backport then we'd be >> stuck deciding who to break. If you have any brilliant ideas then I'm >> all ears. >> >> ...then again, I presume this has been broken since commit >> 88d3457ceb82 ("drm/panel: auo,b116xw03: fix flash backlight when power >> on"). That was a little over 3 years ago. Maybe I'm wrong and somehow >> things still limp along and sorta work even though the panel is >> defined incorrectly? > I dug out a exynos5250-snow out of my pile and booted postmarket OS on > it, which was shockingly easy/pleasant (kudos to those involved!). I > found that it was booting a kernel based on 6.1.24. Digging into > sysfs, I found that indeed it appeared to be using the "panel-edp" > driver, so I guess it is limping along with the wrong driver and wrong > flags... > > It wasn't totally clear for me how to build a new kernel and deploy it > for postmarket OS, so I wasn't able to confirm this change. I've CCed > the person listed on the postmarket OS wiki though to see if they have > any insight. Tested it on peach-pit using linux-next with this patch applied. Panel still works and "dmesg | grep panel" returns panel_simple instead of panel_edp.
Tested-by: Anton Bambura <jenneron@postmarketos.org> > > In any case, it sounds as if things are working well enough on older > OSes, so maybe we can just skip trying to do any stable backport on > this. It still seems like we should land it, though, since the current > state of the world seems pretty broken. Anyone willing to give a > Reviewed-by or Acked-by tag? > > -Doug > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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