Re: [Intel-gfx] [PATCH v2 2/2] drm/i915/display: Do not use stolen on MTL

[Nirmoy Das]

On 7/13/2023 4:56 PM, Andrzej Hajda wrote:

On 13.07.2023 16:45, Nirmoy Das wrote:

On 7/12/2023 12:06 AM, Nirmoy Das wrote:

Use smem on MTL due to a HW bug in MTL that prevents
reading from stolen memory using LMEM BAR.

v2: improve stolen skip detection(Andrzej)

Cc: Oak Zeng <oak.z...@intel.com>
Cc: Jani Nikula <jani.nik...@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahti...@linux.intel.com>
Cc: Andi Shyti <andi.sh...@linux.intel.com>
Cc: Andrzej Hajda <andrzej.ha...@intel.com>
Signed-off-by: Nirmoy Das <nirmoy....@intel.com>
Reviewed-by: Oak Zeng <oak.z...@intel.com>
Reviewed-by: Andrzej Hajda <andrzej.ha...@intel.com>
Reviewed-by: Andi Shyti <andi.sh...@linux.intel.com>
---
  drivers/gpu/drm/i915/display/intel_fbdev.c   | 5 ++++-
  drivers/gpu/drm/i915/display/intel_overlay.c | 5 +++--
  2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_fbdev.c b/drivers/gpu/drm/i915/display/intel_fbdev.c

index 1cc0ddc6a310..e019bbcd474e 100644
--- a/drivers/gpu/drm/i915/display/intel_fbdev.c
+++ b/drivers/gpu/drm/i915/display/intel_fbdev.c

@@ -187,8 +187,11 @@ static int intelfb_alloc(struct drm_fb_helper *helper,            * If the FB is too big, just don't use it since fbdev is not very            * important and we should probably use that space with FBC or other

           * features.
+         *
+         * Also skip stolen on MTL as Wa_22018444074 mitigation.
           */
-        if (size * 2 < dev_priv->dsm.usable_size)
+        if (size * 2 < dev_priv->dsm.usable_size ||
+            !(IS_METEORLAKE(dev_priv)))

Just realized  this is wrong, stolen will be picked on non-mtl even if the stolen usable size is < 2*size which is not expected.

if (!(IS_METEORLAKE(dev_priv)) && size * 2 < dev_priv->dsm.usable_size) ?

that should work, resent with that.


Thanks,

Nirmoy

Regards
Andrzej

I will keep this as v1


Regards,

Nirmoy

              obj = i915_gem_object_create_stolen(dev_priv, size);
          if (IS_ERR(obj))
              obj = i915_gem_object_create_shmem(dev_priv, size);

diff --git a/drivers/gpu/drm/i915/display/intel_overlay.c b/drivers/gpu/drm/i915/display/intel_overlay.c

index d6fe2bbabe55..09c1aa1427ad 100644
--- a/drivers/gpu/drm/i915/display/intel_overlay.c
+++ b/drivers/gpu/drm/i915/display/intel_overlay.c

@@ -1348,11 +1348,12 @@ int intel_overlay_attrs_ioctl(struct drm_device *dev, void *data,   static int get_registers(struct intel_overlay *overlay, bool use_phys)

  {
      struct drm_i915_private *i915 = overlay->i915;
-    struct drm_i915_gem_object *obj;
+    struct drm_i915_gem_object *obj = ERR_PTR(-ENODEV);
      struct i915_vma *vma;
      int err;
  -    obj = i915_gem_object_create_stolen(i915, PAGE_SIZE);
+    if (!IS_METEORLAKE(i915)) /* Wa_22018444074 */
+        obj = i915_gem_object_create_stolen(i915, PAGE_SIZE);
      if (IS_ERR(obj))
          obj = i915_gem_object_create_internal(i915, PAGE_SIZE);
      if (IS_ERR(obj))