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.cregisters a pwm with the generic name "pwm_backlight" and thenthe i915 panel code makes a pwm_get(dev, "pwm_backlight").Some devices use a PMIC Crystal Cove, but the LCD screen is connected tothe 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 theLPSS / 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 thei915 panel to call pwm_get for the right search name according to thebits of the VBT, solves this problem."