On Tue, 2023-04-04 at 23:26 +0200, Das, Nirmoy wrote: > > On 4/4/2023 8:27 PM, Ville Syrjälä wrote: > > On Tue, Apr 04, 2023 at 08:13:42PM +0200, Nirmoy Das wrote: > > > Stolen memory is not usable for MTL A0 stepping beyond > > > certain access size and we have no control over userspace > > > access size of /dev/fb which can be backed by stolen memory. > > > So disable stolen memory backed fb by setting i915- > > > >dsm.usable_size > > > to zero. > > > > > > v2: remove hsdes reference and fix commit message(Andi) > > > v3: use revid as we want to target SOC stepping(Radhakrishna) > > > > > > Cc: Matthew Auld <matthew.auld@xxxxxxxxx> > > > Cc: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx> > > > Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx> > > > Cc: Lucas De Marchi <lucas.demarchi@xxxxxxxxx> > > > Cc: Radhakrishna Sripada <radhakrishna.sripada@xxxxxxxxx> > > > Signed-off-by: Nirmoy Das <nirmoy.das@xxxxxxxxx> > > > Reviewed-by: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx> > > > --- > > > drivers/gpu/drm/i915/gem/i915_gem_stolen.c | 8 ++++++++ > > > 1 file changed, 8 insertions(+) > > > > > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c > > > b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c > > > index 8ac376c24aa2..ee492d823f1b 100644 > > > --- a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c > > > +++ b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c > > > @@ -535,6 +535,14 @@ static int i915_gem_init_stolen(struct > > > intel_memory_region *mem) > > > /* Basic memrange allocator for stolen space. */ > > > drm_mm_init(&i915->mm.stolen, 0, i915->dsm.usable_size); > > > > > > + /* > > > + * Access to stolen lmem beyond certain size for MTL A0 > > > stepping > > > + * would crash the machine. Disable stolen lmem for > > > userspace access > > > + * by setting usable_size to zero. > > > + */ > > > + if (IS_METEORLAKE(i915) && INTEL_REVID(i915) == 0x0) > > > + i915->dsm.usable_size = 0; > > That certainly won't prevent FBC from using stolen. > > Are we sure that FBC accesses are fine? > > I think so. I remember Jouni tested this patch internally to unblock > a > FBC test. > > Jouni, could you please share your thoughts. I can't seem to find the > internal JIRA reference right now. I tested this patch and it was fixing the problem it was targeted. I didn't noticed any issue back then. > > > Regards, > > Nirmoy > > > > > > + > > > return 0; > > > } > > > > > > -- > > > 2.39.0
