On Mon, Dec 19, 2022 at 06:29:27PM +0100, Sasa Dragic wrote: > RC6p on Sandy Bridge got re-enabled over time, causing visual glitches > and GPU hangs. > > Disabled originally in commit 1c8ecf80fdee ("drm/i915: do not enable > RC6p on Sandy Bridge"). re cover letter: > 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. That only kicks in while parked (ie. fully idle from software POV). I think the real bad commit is fb6db0f5bf1d ("drm/i915: Remove unsafe i915.enable_rc6") which seems to affects which rc6 level is selected while unparked. We should mention both of those commits here: Fixes: fb6db0f5bf1d ("drm/i915: Remove unsafe i915.enable_rc6") Fixes: 13c5a577b342 ("drm/i915/gt: Select the deepest available parking mode for rc6") Also we want Cc: stable@xxxxxxxxxxxxxxx We can add those while pushing, so no need to resend for that. > > Signed-off-by: Sasa Dragic <sasa.dragic@xxxxxxxxx> > --- > drivers/gpu/drm/i915/i915_pci.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c > index 668e9da52584..69377564028a 100644 > --- a/drivers/gpu/drm/i915/i915_pci.c > +++ b/drivers/gpu/drm/i915/i915_pci.c > @@ -423,7 +423,8 @@ static const struct intel_device_info ilk_m_info = { > .has_coherent_ggtt = true, \ > .has_llc = 1, \ > .has_rc6 = 1, \ > - .has_rc6p = 1, \ > + /* snb does support rc6p, but enabling it causes various issues */ \ > + .has_rc6p = 0, \ The one downside of doing it this way is that we also lose the debugfs/sysfs files so we can't monitor rc6+/++ residency anymore to make sure they are not entered. I think ideally we'd split this into two parts: which rc6 states the hw actually has vs. which rc6 states we actually want to use. But at least for the time being I think this simple should be sufficient, and should be easy to backport to stable releases. > .has_rps = true, \ > .dma_mask_size = 40, \ > .__runtime.ppgtt_type = INTEL_PPGTT_ALIASING, \ > -- > 2.37.2 -- Ville Syrjälä Intel