Hi dear LKML and community, this is my first post here, so I'd appreciate any guidance or redirection if it's due.
Starting from commit https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i..., HDMI handling for certain refresh rates on my intel iGPU is broken.
The error is still present in 6.16rc1.
Specifically, this is the command that disambiguates the newer broken kernels:
xrandr --output HDMI-1 --auto --scale 1x1 --mode 1920x1080 --rate 120 --pos 0x0 --output eDP-1 --off
The important parts are 1920x1080 and 120Hz. When run on commits prior to the bisected above, it behaves as expected, delivering 1920x1080 @ 120Hz. When run on kernel builds with the above commit included (that commit or later), the monitor goes completely blank. After about 30 seconds, it shuts down entirely (which I assume means that from the monitor's perspective, HDMI got "disconnected").
On this link you can see my original report in the ArchLinux community, where Christian Heusel (@gromit) kindly guided me through the bisection process and built the bisection images for me to try: https://gitlab.archlinux.org/archlinux/packaging/packages/linux/-/issues/145... This link also contains the bisection history.
Additional info:
* The monitor and the notebook are connected via an HDMI cable, the monitor itself is a 4k@120Hz monitor.
* According to `lsmod | grep -E "(i915|Xe)"`, I'm using the i915 kernel driver for the GPU.
* The GPU is an iGPU from intel, specifically `Intel Core Ultra 7 155H`.
* One symptom that disambiguates the working and non-working kernels, besides whether they actually have the bug, is that the broken kernels cause xrandr to additionally report the 144.05 refresh rate as possible for the monitor, whereas the non-broken kernels consistently cause xrandr to only list refresh rate 120 and below as possible. I'm only ever testing the refresh rate of 120, but the presence of the 144.05 rate is correlated.
If any other information or anything is needed, please write.
Thank you, Vas
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#regzbot introduced: 1efd5384277eb71fce20922579061cd3acdb07cf #regzbot title: intel iGPU with HDMI PLL stopped working at 1080p@120Hz 1efd5384 #regzbot link: https://gitlab.archlinux.org/archlinux/packaging/packages/linux/-/issues/145
On Tue, 17 Jun 2025, Vas Novikov vasya.novikov@gmail.com wrote:
If any other information or anything is needed, please write.
Does [1] help?
If not, please file a bug as described at [2], in particular attach dmesg with debugs enabled all the way from boot to reproducing the problem.
Thanks, Jani.
[1] https://lore.kernel.org/r/20250613061246.1118579-1-ankit.k.nautiyal@intel.co... [2] https://drm.pages.freedesktop.org/intel-docs/how-to-file-i915-bugs.html
Hi Jani and everyone,
On 17/06/2025 12.33, Jani Nikula wrote:
Does [1] help?
The patch works. (Applied on top of 6.16.0-rc2-1.1-mainline, built by Christian @gromit who helped again.)
The patch (or the new kernel) also have a side effect of xrandr allowing a completely new refresh rate, ~144Hz. This new refresh also seems to work (I cannot easily disambiguate 144 versus 120, but I can tell it's not 60Hz). So as far as my hardware is concerned, this patch leaves the whole system working in all scenarios that I've tested.
Thanks!
Kind regards, Vas
On Tue, 17 Jun 2025, Vas Novikov vasya.novikov@gmail.com wrote:
Hi Jani and everyone,
On 17/06/2025 12.33, Jani Nikula wrote:
Does [1] help?
The patch works. (Applied on top of 6.16.0-rc2-1.1-mainline, built by Christian @gromit who helped again.)
The patch (or the new kernel) also have a side effect of xrandr allowing a completely new refresh rate, ~144Hz. This new refresh also seems to work (I cannot easily disambiguate 144 versus 120, but I can tell it's not 60Hz). So as far as my hardware is concerned, this patch leaves the whole system working in all scenarios that I've tested.
Thanks a lot for testing! Ankit will send a v2 of it, and I think we'll have it in mainline and backported to stable in a few weeks.
There's no need to file that bug report, this will suffice.
BR, Jani.
linux-stable-mirror@lists.linaro.org
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Jani Nikula -
Vas Novikov