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Re: [i915/drm error] Cannot control brightness

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Hello, I understand you may be busy, however, could you please confirm you have received my request or give me a link to a tracking ticket ? 

Sorry for disturbing, and thank you very much

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Nov 23, 2020, 16:06 by prog-amateur@tutamail.com:

> Hello, the brightness doesn't work (cursor moves but not real brightness). Could you please help or at least forward to the relevant member ? Thank you very much for your kind help. 
> Error message>  :Some messages appear during boot (after grub) :
>
> i915 0000:00:02.0 : [drm] *ERROR* Failed to get the PMIC PWM chip
>  i915 0000:00:02.0 : [drm] *ERROR* [CRTC:51:pipe A] mismatch in pixel_rate
>  i915 0000:00:02.0 : [drm] *ERROR* [CRTC:51:pipe A] mismatch in hw_adjusted_mode.crtc_clock
>  i915 0000:00:02.0 : [drm] *ERROR* [CRTC:51:pipe A] mismatch in port_clock
> Information about device and version>  : My device is an HP Pro Tablet 608 (CPU : Intel Atom X5-Z8500, 64 bits, RAM : 4GB)I am using Debian Testing GNU/Linux 5.9 (but this bug appears also in 5.8, and Stable version), kernel 5.9.0-1-amd64, GNOME 3.38.1 under Wayland.
> Possible solution after test with Fedora (GNOME/Wayland/similar kernel)>  :Brightness can be controlled fine. It seems that this bug has been already fixed in Fedora with patches (c.f. : > https://patchwork.freedesktop.org/series/69686/> ). Summary of this patch is below : 
> "drivers/acpi/acpi_lpss.c and/or driver/mfd/intel_soc_pmic_core.c 
> registers a pwm with the generic name "pwm_backlight" and then 
> the i915 panel code makes a pwm_get(dev, "pwm_backlight"). 
>
> Some devices use a PMIC Crystal Cove, but the LCD screen is connected to 
> the PWM SoC/LPSS controller (and the VBT indicates it correctly), 
> so here the heuristics in drivers/acpi/acpi_lpss.c and mfd/intel_soc_pmic_core.c fail.
>
> This series of patches renames the PWM consultations recorded by the 
> LPSS / intel_soc_pmic_core.c code from "pwm_backlight" to 
> "pwm_soc_backlight" resp. "pwm_pmic_backlight" and, in the case of LPSS, 
> also removes the heuristic. This, combined with teaching the 
> i915 panel to call pwm_get for the right search name according to the 
> bits of the VBT, solves this problem."
>

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[i915/drm error] Cannot control brightness prog-amateur@tutamail.com - 2020-11-23 17:30 +0100
  Re: [i915/drm error] Cannot control brightness prog-amateur@tutamail.com - 2020-11-27 14:50 +0100
    Re: [i915/drm error] Cannot control brightness Dan Ritter <dsr@randomstring.org> - 2020-11-27 15:00 +0100
    Re: [i915/drm error] Cannot control brightness didier gaumet <didier.gaumet@gmail.com> - 2020-11-27 20:30 +0100

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