> -----Original Message-----
> From: Das, Nirmoy <nirmoy....@intel.com>
> Sent: Tuesday, April 4, 2023 11:14 AM
> To: intel-...@lists.freedesktop.org
> Cc: dri-devel@lists.freedesktop.org; Das, Nirmoy <nirmoy....@intel.com>;
> Auld, Matthew <matthew.a...@intel.com>; Andi Shyti
> <andi.sh...@linux.intel.com>; Ceraolo Spurio, Daniele
> <daniele.ceraolospu...@intel.com>; De Marchi, Lucas
> <lucas.demar...@intel.com>; Sripada, Radhakrishna
> <radhakrishna.srip...@intel.com>
> Subject: [PATCH v3] drm/i915/mtl: Disable stolen memory backed FB for A0
>
> 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.a...@intel.com>
> Cc: Andi Shyti <andi.sh...@linux.intel.com>
> Cc: Daniele Ceraolo Spurio <daniele.ceraolospu...@intel.com>
> Cc: Lucas De Marchi <lucas.demar...@intel.com>
> Cc: Radhakrishna Sripada <radhakrishna.srip...@intel.com>
> Signed-off-by: Nirmoy Das <nirmoy....@intel.com>
> Reviewed-by: Andi Shyti <andi.sh...@linux.intel.com>
LGTM,
Reviewed-by: Radhakrishna Sripada <radhakrishna.srip...@intel.com>
> ---
> 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;
> +
> return 0;
> }
>
> --
> 2.39.0
