Arch Linux User Repository

Should linux-headers not be part of makedeps?

Here it is: https://aur.archlinux.org/packages/ddcci-driver-linux-dkms-git . Currently works even with 6.9

I have decided to wait for upstream to tag their new version rather than patch 3eb20df68a545d07b8501f13fa9d20e9c6f577ed (upstream probably hasn't done so in light of https://gitlab.com/ddcci-driver-linux/ddcci-driver-linux/-/merge_requests/15#note_1830989470 's citation that the commit causes a new regression even for kernel version 6.7).

To satisfy people's needs, someone can create and maintain the -git package variant. If nobody does so within a few days, I can.

As mentioned here, running the following makes ddcci/ddcci_backlight pick up the device in 6.8 with the most recent upstream commit:

echo 'ddcci 0x37' | sudo tee /sys/bus/i2c/devices/i2c-7/new_device

Now my backlight control works ＼(^o^)／

A different (or multiple) i2c device may be needed on your system, just check the destination of the symlinks in /sys/bus/i2c/devices. The one(s) you want will go to a DRM card-connector sysfs. 0x37 is the address where the ddc/ci protocol is used so it should not be changed.

Forgot to say I'm also on Intel iGPU. Mesa, mkinitcpio, linux 6.8.9, 15.patch, dkms and linux-headers, everything is installed and set up correctly but GNOME does not show the slider like before Linux 6.8.

It also doesn't work for me either on 6.8, no messages in dmesg. Interestingly, KDE Plasma can still change the brightness over ddc/ci, even without the module loaded (but only on AMDGPU, it doesn't seem to work with an Intel iGPU, but ddcutil is still working).

@dreieck were you able to see the slider in Gnome or another window manager?

I patched and built it for Linux 6.8 and installed it. I have the module in mkinitcpio.conf to load at early boot but GNOME still won't show the slider. Any help?

Patch for Linux 6.8 has now been incorporated into git master branch of upstream: https://gitlab.com/ddcci-driver-linux/ddcci-driver-linux/-/merge_requests/15

No new release yet, so I recommend that in the meantime you add the following patch manually to the PKGBUILD:
https://gitlab.com/ddcci-driver-linux/ddcci-driver-linux/-/merge_requests/15.patch

Hello, I'm new to ddcci-driver-linux-dkms, here's what I've attempted to fix it for Linux 6.8:

diff --git a/PKGBUILD b/PKGBUILD
index a18311b..3b8d57f 100644
--- a/PKGBUILD
+++ b/PKGBUILD
@@ -13,10 +13,15 @@ depends=('dkms')
 conflicts=("ddcci-driver-linux")
 source=(
   "https://gitlab.com/ddcci-driver-linux/ddcci-driver-linux/-/archive/v${pkgver}/ddcci-driver-linux-v${pkgver}.tar.gz"
+  "fix-linux-6.8.patch"
 )
 b2sums=('09c025953410adb5f8253e36d32400cf1ee8bf7bfd39a2ffc43784a92211e354fac5b8ed891eaa0c9395317d63982abfca00da99d2ee8f7028d28af37ec1f6b7'
-        )
+        '4837fb645b71baa86ddf9ea26977821bcc9285c895abf017f9e6cf815a95462dd97d13dfb4104f88aae4d9d9fcab625dd118b8bdf473fa143f9e3224faf2ad88')

+build() {
+  cd "${srcdir}/ddcci-driver-linux-v${pkgver}"
+  patch -Np1 -i ../fix-linux-6.8.patch
+}

 package() {
   local destdir="${pkgdir}/usr/src/ddcci-${pkgver}"
diff --git a/fix-linux-6.8.patch b/fix-linux-6.8.patch
new file mode 100644
index 0000000..1e7d2f9
--- /dev/null
+++ b/fix-linux-6.8.patch
@@ -0,0 +1,25 @@
+--- a/ddcci/ddcci.c
++++ b/ddcci/ddcci.c
+@@ -31,6 +31,10 @@
+ #define DEVICE_NAME "ddcci"
+ #define DDCCI_MAX_CAP_CHUNKS 200
+ 
++#if LINUX_VERSION_CODE >= KERNEL_VERSION(6, 8, 0)
++#define I2C_CLASS_DDC          (1<<3)  /* DDC bus on graphics adapters */
++#endif
++
+ static unsigned int delay = 60;
+ static unsigned short autoprobe_addrs[127] = {0xF0, 0xF2, 0xF4, 0xF6, 0xF8};
+ static int autoprobe_addr_count = 5;
+@@ -1666,7 +1670,11 @@ static int ddcci_detect(struct i2c_clien
+   pr_debug("detected %d:%02x\n", client->adapter->nr, outer_addr);
+ 
+   /* set device type */
++#if LINUX_VERSION_CODE >= KERNEL_VERSION(6, 8, 0)
++  strscpy(info->type, (outer_addr == DDCCI_DEFAULT_DEVICE_ADDR) ? "ddcci" : "ddcci-dependent", I2C_NAME_SIZE);
++#else
+   strlcpy(info->type, (outer_addr == DDCCI_DEFAULT_DEVICE_ADDR) ? "ddcci" : "ddcci-dependent", I2C_NAME_SIZE);
++#endif
+ 
+   return 0;
+ }

... which doesn't seem to fix the problem. With all debug info turned into warnings, I get this:

[ 1683.513585] ddcci: ddcci driver initialized
[ 1683.513916] ddcci: registering driver [ddcci-backlight]
[ 1683.513927] ddcci: driver [ddcci-backlight] registered

... which means that init is called, but probe is not.

"Useful" links:

• https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e965a707276760cc010eb77fba64b08ee9e8781f
• ^ the place where all class-based autodetect are removed from major HDMI controller drivers
• https://review.lttng.org/c/lttng-modules/+/11701/7/src/lib/ringbuffer/ring_buffer_backend.c#418
• ^ they also had to work around strlcpy.

The most straightforward fix I see is to revert e965a707276760cc010eb77fba64b08ee9e8781f in the kernel.