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

[Nirmoy Das <nirmoy.das@xxxxxxxxxxxxxxx>]

On 7/6/2023 3:32 PM, Tvrtko Ursulin wrote:
> On 30/06/2023 18:01, Nirmoy Das wrote:
> > Use smem on MTL due to a HW bug in MTL that prevents
> > reading from stolen memory using LMEM BAR.
>
> Does anything remain in stolen or could the memory region just not be 
> created?


GSC requires DSM which can't use smem for another bug.


Regards,

Nirmoy


> Regards,
>
> Tvrtko
>
> > Cc: Oak Zeng <oak.zeng@xxxxxxxxx>
> > Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
> > Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> > Cc: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx>
> > Cc: Andrzej Hajda <andrzej.hajda@xxxxxxxxx>
> > Signed-off-by: Nirmoy Das <nirmoy.das@xxxxxxxxx>
> > ---
> >   drivers/gpu/drm/i915/display/intel_fbdev.c   | 2 ++
> >   drivers/gpu/drm/i915/display/intel_overlay.c | 7 ++++---
> >   2 files changed, 6 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..10e38d60f9ef 100644
> > --- a/drivers/gpu/drm/i915/display/intel_fbdev.c
> > +++ b/drivers/gpu/drm/i915/display/intel_fbdev.c
> > @@ -182,6 +182,8 @@ static int intelfb_alloc(struct drm_fb_helper 
> > *helper,
> >           obj = i915_gem_object_create_lmem(dev_priv, size,
> >                             I915_BO_ALLOC_CONTIGUOUS |
> >                             I915_BO_ALLOC_USER);
> > +    } else if (IS_METEORLAKE(dev_priv)) { /* Wa_22018444074 */
> > +        obj = i915_gem_object_create_shmem(dev_priv, size);
> >       } else {
> >           /*
> >            * If the FB is too big, just don't use it since fbdev is 
> > not very
> > diff --git a/drivers/gpu/drm/i915/display/intel_overlay.c 
> > b/drivers/gpu/drm/i915/display/intel_overlay.c
> > index d6fe2bbabe55..05ae446c8a56 100644
> > --- a/drivers/gpu/drm/i915/display/intel_overlay.c
> > +++ b/drivers/gpu/drm/i915/display/intel_overlay.c
> > @@ -1348,12 +1348,13 @@ 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 = NULL;
> >       struct i915_vma *vma;
> >       int err;
> >   -    obj = i915_gem_object_create_stolen(i915, PAGE_SIZE);
> > -    if (IS_ERR(obj))
> > +    if (!IS_METEORLAKE(i915)) /* Wa_22018444074 */
> > +        obj = i915_gem_object_create_stolen(i915, PAGE_SIZE);
> > +    if (IS_ERR_OR_NULL(obj))
> >           obj = i915_gem_object_create_internal(i915, PAGE_SIZE);
> >       if (IS_ERR(obj))
> >           return PTR_ERR(obj);