On Mon, Oct 23, 2023 at 07:35:36AM -0700, Doug Anderson wrote:
> Hi,
>
> On Mon, Oct 23, 2023 at 4:12 AM Greg Kroah-Hartman
> <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> >
> > 6.5-stable review patch. If anyone has any objections, please let me know.
> >
> > ------------------
> >
> > From: Douglas Anderson <dianders@xxxxxxxxxxxx>
> >
> > [ Upstream commit ad3e33fe071dffea07279f96dab4f3773c430fe2 ]
> >
> > 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")
> > Tested-by: Anton Bambura <jenneron@xxxxxxxxxxxxxxxx>
> > Acked-by: Hsin-Yi Wang <hsinyi@xxxxxxxxxxxx>
> > Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
> > Link: https://patchwork.freedesktop.org/patch/msgid/20230925150010.1.Iff672233861bcc4cf25a7ad0a81308adc3bda8a4@changeid
> > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> > ---
> > drivers/gpu/drm/panel/panel-edp.c | 29 -----------------------
> > drivers/gpu/drm/panel/panel-simple.c | 35 ++++++++++++++++++++++++++++
> > 2 files changed, 35 insertions(+), 29 deletions(-)
>
> I responded to Sasha but managed to miss CCing stable@. My
> apologies... Copying what I wrote there:
>
> ---
>
> I feel that this should not be added to any stable trees. Please
> remove it from the 6.1 and 6.5 stable trees and, if possible, mark it
> so it won't get auto-selected in the future.
>
> The issue here is that several mediatek boards ended up (incorrectly)
> claiming that they included this panel and this change has the
> possibility to break those boards. In the latest upstream kernel
> mediatek boards that were using it have switched to the generic
> "edp-panel" compatible string, but if this is backported someplace
> before that change it has the potential to break folks.
>
> It should be noted that it was confirmed that the "snow" and
> "peach-pit" boards appeared to be working even without this patch, so
> there is no burning need (even for those boards) to get this patch
> backported.
>
> For discussion on the topic, please see the link pointed to by the patch, AKA:
>
> https://patchwork.freedesktop.org/patch/msgid/20230925150010.1.Iff672233861bcc4cf25a7ad0a81308adc3bda8a4@changeid
>
> ---
>
> Sasha has already said he'd remove it from the queue, but responding
> here just in case it's important. Thanks!
He's dropped them now, thanks!
greg k-h
