[PATCH 0/1][SRU][F][G][unstable][OEM-5.10] Stop using get_scalar_status command in Dell AIO uart backlight driver Edit

[AceLan Kao]

Yes, we are planning to upstream this driver, but it's required to
re-write the driver with serdev.
I got some troubles while re-writing it and then got distracted by
other bugs, so the plan has been suspended for quite a long time.

Currently we're enabling new AIOs, and require this updated function.
At least this fix is needed in the OEM-5.10 kernel for shipment, but
it would be better that 5.4 kernel could include this fix, too.
I'll resume the upstream plan as soon as possible.

Stefan Bader <stefan.bader at canonical.com> 於 2021年1月15日 週五 下午4:45寫道：
>
> On 17.12.20 09:08, AceLan Kao wrote:
> > From: "Chia-Lin Kao (AceLan)" <acelan.kao at canonical.com>
> >
> > BugLink: https://bugs.launchpad.net/bugs/1865402
> >
> > [Impact]
> > The get_scalar_status command was provided by ODM engineer and was newly
> > introduced to determinate whether scalar is responsible for the backlight
> > adjustment. That guy asked the scalar vendor to add this command and the
> > command works as expected. But there is already a command in the Dell AIO
> > scalar UART command spec. which can do the same thing since 2015, and the
> > newly introduced get_scalar_status command is undocumented. To prevent
> > from introducing regression in the future and to align with what Windows
> > uses, replace this command with get_display_mode command.
> >
> > [Fix]
> > Replace get_scalar_status command with get_display_mode command.
> >
> > [Test]
> > Verified on new Dell AIO platforms.
> >
> > [Regression Potential]
> > Low, the command is already in the spec. since 2015.
>
> That does not necessarily mean it works. I am probably rather hesitant here
> because I got burned a very long time ago when trying to fix some ACPI backlight
> issue. This started to become a nightmare ping-ponging between fixing new
> hardware while breaking older on in turn. Or the other way round.
> So, as simple as it looks, imo, this should be upstream with some settle time
> before going into a stable kernel.
>
> -Stefan
> >
> > Chia-Lin Kao (AceLan) (1):
> >   UBUNTU: SAUCE: platform/x86: dell-uart-backlight: add get_display_mode
> >     command
> >
> >  drivers/platform/x86/dell-uart-backlight.c | 91 +++++++++++-----------
> >  drivers/platform/x86/dell-uart-backlight.h |  7 +-
> >  2 files changed, 52 insertions(+), 46 deletions(-)
> >
>
>