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? > + > return 0; > } > > -- > 2.39.0 -- Ville Syrjälä Intel
