Modesetting driver cannot exceed pipeline dimensions reported by kernel (8192x8192). The old intel driver could.

[Kristian Robertsen]

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.

[Kristian Robertsen (kristian-robertsen)]

Update. This is a functional regression as a result of switching to modesetting.
Source: https://bugs.freedesktop.org/show_bug.cgi?id=107840#c1

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1790390

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Daniel van Vugt (vanvugt)]

Is it possible you're confusing the max texture size for max framebuffer size?

Can you share that link to "Intel's own hardware pages"?

[Daniel van Vugt (vanvugt)]

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.

[Daniel van Vugt (vanvugt)]

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.