Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.debian.user > #228968

[i915/drm error] Cannot control brightness

Show all headers | View raw

[Multipart message — attachments visible in raw view] - view raw

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."

Back to linux.debian.user | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

[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

csiph-web