Hi all, RC6p got re-enabled on Sandy Bridge over time, seemingly by accident over time, causing graphical glitches and occasional GPU hangs on my old ThinkPad T420, severity depending on kernel version. It is a known issue, e.g.: https://wiki.ubuntu.com/Kernel/PowerManagementRC6 https://www.yoctoproject.org/pipermail/yocto/2012-June/007164.html It was originally disabled in commit 1c8ecf80fdee ("drm/i915: do not enable RC6p on Sandy Bridge"), and subsequently re-enabled by 13c5a577b342 ("drm/i915/gt: Select the deepest available parking mode for rc6"), which seems to focus only on Ivy Bridge. This patch re-disables RC6p on Sandy Bridge. I don't know if this issue is fixed otherwise, and I just have a faulty hardware, but there are few unresolved Sandy Bridge issues floating on the net, which could be related to this. When disabling RC6p graphics works flawlessly, as it also works on 4.15 kernel without modifications. I didn't want to clutter this mail with too much info, so feel free to ask for details, links or to file bug report if necessary. Thanks, Sasa Sasa Dragic (1): drm/i915: re-disable RC6p on Sandy Bridge drivers/gpu/drm/i915/i915_pci.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) -- 2.37.2
