*** This bug is a duplicate of bug 1714178 ***
https://bugs.launchpad.net/bugs/1714178
Thank you for taking the time to report this bug and helping to make
Ubuntu better. This particular bug has already been reported and is a
duplicate of bug 1714178, so it is being marked as such. Please look at
the other bug report to see if there is any missing information that you
can provide, or to see if there is a workaround for the bug.
Additionally, any further discussion regarding the bug should occur in
the other report. Feel free to continue to report any other bugs you may
find.
** This bug has been marked a duplicate of bug 1714178
Triple 4K monitor display failed (modesetting driver)
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Packages, which is subscribed to xorg-server in Ubuntu.
https://bugs.launchpad.net/bugs/1790390
Title:
Modesetting driver cannot exceed pipeline dimensions reported by
kernel (8192x8192). The old intel driver could.
Status in X.Org X server:
Unknown
Status in xorg-server package in Ubuntu:
Triaged
Bug description:
The i915 driver in the Linux kernel misrepresents the max output of
certain, newer, GPUs.
The output should be 16384x16384 for newer models (on at least 7th and
8th gen Intel CPUs) but it is stuck in 8192x8192.
The problem lies in:
https://github.com/torvalds/linux/blob/master/drivers/gpu/drm/i915/intel_display.c
The conditional branch which is wrong is:
/* maximum framebuffer dimensions */
if (IS_GEN2(dev_priv)) {
dev->mode_config.max_width = 2048;
dev->mode_config.max_height = 2048;
} else if (IS_GEN3(dev_priv)) {
dev->mode_config.max_width = 4096;
dev->mode_config.max_height = 4096;
} else {
dev->mode_config.max_width = 8192;
dev->mode_config.max_height = 8192;
}
While I'm not certain which generations specifically allows the higher
output it is most certainly true of all iGPUs on the 7th and 8th
generation CPUs.
This is corroborated by Intel's own hardware pages, and can be proven
by running Wayland which ignores the limitation in the driver.
Bug is present both on all Ubuntu releases, including 18.04.
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https://bugs.launchpad.net/xorg-server/+bug/1790390/+subscriptions
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