Build errors on kernel 6.5.0-10-generic

[tr33]

I updated to ubuntu 23.10 which has kernel 6.5.0.

Building the module from git fails with

# make make -C /lib/modules/6.5.0-10-generic/build M=/usr/src/mba6x_bl modules make[1]: Verzeichnis „/usr/src/linux-headers-6.5.0-10-generic“ wird betreten warning: the compiler differs from the one used to build the kernel The kernel was built by: x86_64-linux-gnu-gcc-13 (Ubuntu 13.2.0-4ubuntu3) 13.2.0 You are using: gcc-13 (Ubuntu 13.2.0-4ubuntu3) 13.2.0 CC [M] /usr/src/mba6x_bl/mba6x_bl.o /usr/src/mba6x_bl/mba6x_bl.c: In function ‘platform_probe’: /usr/src/mba6x_bl/mba6x_bl.c:325:9: error: implicit declaration of function ‘acpi_video_set_dmi_backlight_type’; did you mean ‘acpi_video_get_backlight_type’? [-Werror=implicit-function-declaration] 325 | acpi_video_set_dmi_backlight_type(acpi_backlight_vendor); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | acpi_video_get_backlight_type cc1: some warnings being treated as errors make[3]: *** [scripts/Makefile.build:251: /usr/src/mba6x_bl/mba6x_bl.o] Fehler 1 make[2]: *** [/usr/src/linux-headers-6.5.0-10-generic/Makefile:2037: /usr/src/mba6x_bl] Fehler 2 make[1]: *** [Makefile:234: __sub-make] Fehler 2 make[1]: Verzeichnis „/usr/src/linux-headers-6.5.0-10-generic“ wird verlassen make: *** [Makefile:8: all] Fehler 2

is the driver still required, or did it go upstream?

[patjak]

The driver was intended to work around a bug in the i915 driver. The bug was eventually fixed so this driver is no longer needed.

It does, however give you a much more linear brightness curve so I kept using it for a while. But I haven't touch the machine for quite a few years so I have no idea if it still works. I know nothing about the Ubuntu package but it looks like the kernel API has changed.

[tr33]

The brightness is not adjustable at all in kernel 6.5, probably because /sys/class/backlight is empty.

[patjak]

Then that's a different issue all together. Is i915 loading properly?

[tr33]

It look like its being loaded:

# lsmod|grep i915 i915 4145152 41 drm_buddy 20480 1 i915 i2c_algo_bit 16384 1 i915 ttm 110592 1 i915 drm_display_helper 241664 1 i915 cec 94208 2 drm_display_helper,i915 drm_kms_helper 270336 2 drm_display_helper,i915 drm 761856 44 drm_kms_helper,drm_display_helper,drm_buddy,i915,ttm video 73728 2 apple_bl,i915

dmesg output:

# dmesg|grep i915 [ 0.000000] Command line: BOOT_IMAGE=/vmlinuz-6.5.0-10-generic root=/dev/mapper/vgubuntu-root ro crashkernel=384M-:128M i915.enable_dpcd_backlight=1 acpi_backlight=vendor libata.force=1:noncq intel_idle.max_cstate=1 pcie_aspm=force i915.enable_psr=0 i915.i915_enable_rc6=1 i915.i915_enable_fbc=1 i915.lvds_downclock=1 kopt=root=/dev/mapper/vgubuntu-root resume=/dev/mapper/vgubuntu-swap quiet splash vt.handoff=7 [ 0.041715] Kernel command line: BOOT_IMAGE=/vmlinuz-6.5.0-10-generic root=/dev/mapper/vgubuntu-root ro crashkernel=384M-:128M i915.enable_dpcd_backlight=1 acpi_backlight=vendor libata.force=1:noncq intel_idle.max_cstate=1 pcie_aspm=force i915.enable_psr=0 i915.i915_enable_rc6=1 i915.i915_enable_fbc=1 i915.lvds_downclock=1 kopt=root=/dev/mapper/vgubuntu-root resume=/dev/mapper/vgubuntu-swap quiet splash vt.handoff=7 [ 3.176906] i915: unknown parameter 'i915_enable_rc6' ignored [ 3.176909] i915: unknown parameter 'i915_enable_fbc' ignored [ 3.176911] i915: unknown parameter 'lvds_downclock' ignored [ 3.178146] i915 0000:00:02.0: vgaarb: deactivate vga console [ 3.179177] i915 0000:00:02.0: vgaarb: changed VGA decodes: olddecodes=io+mem,decodes=io+mem:owns=io+mem [ 3.241904] i915 0000:00:02.0: [drm] Skipping intel_backlight registration [ 3.242479] [drm] Initialized i915 1.6.0 20201103 for 0000:00:02.0 on minor 0 [ 3.513817] fbcon: i915drmfb (fb0) is primary device [ 4.945114] i915 0000:00:02.0: [drm] fb0: i915drmfb frame buffer device [ 17.150192] snd_hda_intel 0000:00:03.0: bound 0000:00:02.0 (ops i915_audio_component_bind_ops [i915])

[patjak]

Why are you passing all those kernel parameters to the i915 driver?

[ 3.241904] i915 0000:00:02.0: [drm] Skipping intel_backlight registration The above line tells you that the i915 driver is skipping it's backlight registration.

Try removing: i915.enable_dpcd_backlight=1 acpi_backlight=vendor

And you can also remove the following since they are not being used: [ 3.176906] i915: unknown parameter 'i915_enable_rc6' ignored [ 3.176909] i915: unknown parameter 'i915_enable_fbc' ignored [ 3.176911] i915: unknown parameter 'lvds_downclock' ignored

[tr33]

The parameters are there for historical reasons: someone previously mentioned that these parameters fixed some problems - since then I have never read again whether they are still necessary. Because the machine was running pretty fine 🤷🏻‍♂️

removed both parameters -> works! AWESOME 💋😘

how about the other parameters - are they still necessary?

[patjak]

If the machine is running fine I wouldn't bother. It's been to long since I used my MBA 6.2 to remember which quirks was actually useful. I'll close this issue now. Thanks.