Re: [REGRESSION] Backlight control broken on Dell G15 5515 since 6.1

[Daniel Dadap <ddadap@nvidia.com>]

On Tue, Jan 10, 2023 at 07:03:02PM +0200, Youssef Aly wrote:
> Hi,
> 
> Happy to test anytime, thanks for the p.s.
> 
> I would like to mention something probably unrelated, but thought I
> would mention it just in case. The backlight control has been broken
> on windows 10/11 on hybrid mode since Nvidia driver 526.47, this issue
> only affects the 3060 models (They have a mux switch). This is a link
> to the forum discussing the issue
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.dell.com%2Fcommunity%2FInspiron%2FG15-5515-Ryzen-Edition-Display-Brightness-Slider-not-Working%2Fm-p%2F8301504%23M154120&data=05%7C01%7Cddadap%40nvidia.com%7Cc5ba4337bec048cc9ec908daf32c9029%7C43083d15727340c1b7db39efd9ccc17a%7C0%7C0%7C638089669973715824%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=A7zkgMfX1Vbucho27pQSrW6dgIULEbIsFeEpekA9IfQ%3D&reserved=0
> .
> 
> Hope that is of some help.


Thanks, Youssef. Knowing that this is also broken on Windows will help.
 
> Thanks,
> 
> Youssef
> 
> 
> 
> On Tue, 10 Jan 2023 at 17:28, Hans de Goede <hdegoede@redhat.com> wrote:
> >
> > Hi,
> >
> > On 1/10/23 16:19, Youssef Aly wrote:
> > > Hi Hans,
> > >
> > > Yes, I added "acpi_backlight=nvidia_wmi_ec" to
> > > the kernel commandline for the patched kernel, it doesn't work without it.
> > >
> > > I have 2 modes in the bios Hybrid on/off (hybrid / discrete). I tried
> > > the modes with "acpi_backlight=nvidia_wmi_ec" and
> > > "acpi_backlight=native" using the patched kernel (v6.1.4):
> > >
> > > Hybrid:
> > > "acpi_backlight=native": Does not work, /sys/class/backlight contains
> > > amdgpu_bl1.
> > > "acpi_backlight=nvidia_wmi_ec": Works as expected,
> > > /sys/class/backlight contains nvidia_wmi_ec_backlight.
> > >
> > > Discrete:
> > > "acpi_backlight=native": Works but when brightness from 0-10 is the
> > > same as 0-100, for example 10 is full brightness like 100, 8 is the
> > > same as 80, etc... ,
> > > /sys/class/backlight contains nvidia_0.
> > > "acpi_backlight=nvidia_wmi_ec": Does not work, /sys/class/backlight
> > > contains nvidia_wmi_ec_backlight.
> >
> > Thank you for testing!
> >
> > Ok so it seems there are 2 issues at play here:
> >
> > 1. Depending on the BIOS setting we need to use either native (discrete mode)
> >    or nvidia_wmi_ec (hybrid mode)
> >
> > 2. There is a bug in the nvidia binary drivers backlight control in native
> >    mode on this system causing the range to be wrong
> >
> > Daniel, we really need help from NVidia with fixing 1. can you see if
> > there is a way to check the BIOS setting/mode from inside the kernel ?
> >
> > Regards,
> >
> > Hans
> >
> > p.s.
> >
> > Youssef, for your next email please use reply to all. You keep dropping
> > Daniel and the regressions-list from the To/Cc, using reply-to-all should
> > keep these in the To/Cc.
> >
> >
> >
> >
> > > On Tue, 10 Jan 2023 at 10:39, Hans de Goede <hdegoede@redhat.com> wrote:
> > >>
> > >> Hi,
> > >>
> > >> On 1/10/23 02:07, Youssef Aly wrote:
> > >>> Hello,
> > >>>
> > >>> Just reporting back, building with the patch fixed the issue.
> > >>
> > >> I assume that you also added "acpi_backlight=nvidia_wmi_ec" to
> > >> the kernel commandline for the patched kernel, right ?
> > >>
> > >> If you have time, can you please also check the other BIOS
> > >> (hybrid / discrete / ...) modes in the BIOS?
> > >>
> > >> Based on the previous bug report, I would expect you to need
> > >> to pass "acpi_backlight=native" in at least some of the other
> > >> modes ...
> > >>
> > >> Regards,
> > >>
> > >> Hans
> > >>
> > >>
> > >>
> > >>> On Mon, 9 Jan 2023 at 22:23, Youssef Aly <youssefaswad@gmail.com> wrote:
> > >>>>
> > >>>> Hello Hans,
> > >>>>
> > >>>> Ok, I'll try building with the patch you provided, and report back.
> > >>>>
> > >>>> Thanks,
> > >>>>
> > >>>> Youssef
> > >>>>
> > >>>> On Mon, 9 Jan 2023 at 21:19, Hans de Goede <hdegoede@redhat.com> wrote:
> > >>>>>
> > >>>>> Hi Youssef,
> > >>>>>
> > >>>>> On 1/9/23 17:18, Youssef Aly wrote:
> > >>>>>> Hello,
> > >>>>>>
> > >>>>>> The backlight control has been broken on Dell G15 5515 since 6.1, it
> > >>>>>> is always at full brightness, this is only the case in hybrid (mux)
> > >>>>>> graphics mode.
> > >>>>>>
> > >>>>>> As per the output of lsmod the nvidia_wmi_ec_backlight is loaded:
> > >>>>>> nvidia_wmi_ec_backlight    16384  0
> > >>>>>> video                  61440  5
> > >>>>>> nvidia_wmi_ec_backlight,dell_wmi,amdgpu,dell_laptop,nvidia_modeset
> > >>>>>> wmi                    36864  7
> > >>>>>> video,nvidia_wmi_ec_backlight,alienware_wmi,dell_wmi,wmi_bmof,dell_smbios,dell_wmi_descriptor
> > >>>>>>
> > >>>>>> but it is not present in /sys/class/backlight, only amdgpu_bl1 is
> > >>>>>> present which is not functional
> > >>>>>> contents of /sys/class/backlight
> > >>>>>> total 0
> > >>>>>> lrwxrwxrwx 1 root root 0 Jan  9 00:49 amdgpu_bl1 ->
> > >>>>>> ../../devices/pci0000:00/0000:00:08.1/0000:06:00.0/backlight/amdgpu_bl1/
> > >>>>>>
> > >>>>>> this is the content on 6.0.12
> > >>>>>> total 0
> > >>>>>> lrwxrwxrwx 1 root root 0 Jan  8 20:59 amdgpu_bl1 ->
> > >>>>>> ../../devices/pci0000:00/0000:00:08.1/0000:06:00.0/backlight/amdgpu_bl1/
> > >>>>>> lrwxrwxrwx 1 root root 0 Jan  8 20:59 nvidia_wmi_ec_backlight ->
> > >>>>>> ../../devices/pci0000:00/PNP0C14:00/wmi_bus/wmi_bus-PNP0C14:00/603E9613-EF25-4338-A3D0-C46177516DB7/backlight/nvidia_wmi_ec_backlight/
> > >>>>>>
> > >>>>>> Distro: Endeavour OS
> > >>>>>> Kernel: 6.1.4-arch1-1
> > >>>>>> GPU: RTX 3060 Using nvidia proprietary drivers version 525.78.01
> > >>>>>>
> > >>>>>> #regzbot introduced v6.1..v6.1.4
> > >>>>>
> > >>>>> Hmm, this is likely caused by:
> > >>>>>
> > >>>>> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.kernel.org%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Ftorvalds%2Flinux.git%2Fcommit%2F%3Fid%3Df46acc1efd4b5846de9fa05f966e504f328f34a6&data=05%7C01%7Cddadap%40nvidia.com%7Cc5ba4337bec048cc9ec908daf32c9029%7C43083d15727340c1b7db39efd9ccc17a%7C0%7C0%7C638089669973715824%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=uWiblfqPL%2BrX9MmIGbzTyFTAkcdD1KXT2SSFxWKJ01M%3D&reserved=0
> > >>>>>
> > >>>>> Which was added because according to the reporter on their G15 5515
> > >>>>> backlight control only works in native mode ...
> > >>>>>
> > >>>>> I'm getting the feeling that we need to detect the BIOS setting
> > >>>>> and use a different backlight device depending on the setting...
> > >>>>>
> > >>>>> Daniel, any ideas?
> > >>>>>
> > >>>>> For now can you try building a kernel with the attached patch
> > >>>>> (which I've also just submitted upstream) and with:
> > >>>>>
> > >>>>> acpi_backlight=nvidia_wmi_ec
> > >>>>>
> > >>>>> added to your kernel commandline. That should work around this
> > >>>>> for now...
> > >>>>>
> > >>>>> Regards,
> > >>>>>
> > >>>>> Hans
> > >>>
> > >>
> > >
> >