*** This bug is a duplicate of bug 1714178 ***
https://bugs.launchpad.net/bugs/1714178
Actually Chris's comment explains everything:
https://bugs.freedesktop.org/show_bug.cgi?id=107840#c1
So the kernel is behaving correctly. And the modesetting driver is doing
its best. But it sounds like "its best" can possibly be improved.
** Package changed: linux (Ubuntu) => xorg-server (Ubuntu)
** Changed in: xorg-server (Ubuntu)
Importance: Undecided => Medium
** Changed in: xorg-server (Ubuntu)
Status: Incomplete => Triaged
** Summary changed:
- Xorg cannot exceed pipeline dimensions reported by kernel
+ Modesetting driver cannot exceed pipeline dimensions reported by kernel
** Also affects: xorg-server via
https://bugs.freedesktop.org/show_bug.cgi?id=107840
Importance: Unknown
Status: Unknown
** Summary changed:
- Modesetting driver cannot exceed pipeline dimensions reported by kernel
+ Modesetting driver cannot exceed pipeline dimensions reported by kernel
(8192x8192)
** Summary changed:
- Modesetting driver cannot exceed pipeline dimensions reported by kernel
(8192x8192)
+ Modesetting driver cannot exceed pipeline dimensions reported by kernel
(8192x8192). The old intel driver could.
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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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