On Mon, Mar 10, 2025 at 12:31:21PM +0100, Florian Bezdeka wrote:
> Hi all,
>
> the following commit (taken from 6.6-rt branch) resides in all stable-
> rt branches but is not part of mainline 6.12 and above, which makes it
> impossible to use i915 in combination with PREEMPT_RT enabled.
>
> Is that by intention? Are there any known issues that makes it
> necessary to disable i915 in combination with RT in current releases?
There is a set of changes that were not merged along with the PREEMPT_RT
bits that are required to have i915 behaving properly (or as well as
possible) wrt PREEMPT_RT. While those changes are not carried by the driver
(i915) itself, they are available here:
* git tree:
https://web.git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git/tree/patches?h=linux-6.12.y-rt-patches&id=b7402ed929a05397b5c02802bdfaae40df4f2fc8
* patches:
https://cdn.kernel.org/pub/linux/kernel/projects/rt/6.12/
Best regards,
Luis
> Best regards,
> Florian
>
> commit f532acfe5c63d53756c86e3d3fb1a51b02d29762
> Author: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> Date: Mon Feb 21 17:59:14 2022 +0100
>
> Revert "drm/i915: Depend on !PREEMPT_RT."
>
> Once the known issues are addressed, it should be safe to enable the
> driver.
>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
>
> diff --git a/drivers/gpu/drm/i915/Kconfig b/drivers/gpu/drm/i915/Kconfig
> index 3efce05d7b57..392d51703096 100644
> --- a/drivers/gpu/drm/i915/Kconfig
> +++ b/drivers/gpu/drm/i915/Kconfig
> @@ -3,7 +3,6 @@ config DRM_I915
> tristate "Intel 8xx/9xx/G3x/G4x/HD Graphics"
> depends on DRM
> depends on X86 && PCI
> - depends on !PREEMPT_RT
> select INTEL_GTT if X86
> select INTERVAL_TREE
> # we need shmfs for the swappable backing store, and in particular
>
---end quoted text---
