Re: [PATCH v5 6/9] drm/xe/display: Update intel_bo_read_from_page to use ttm_bo_access

[Matthew Brost <matthew.brost@intel.com>]

On Tue, Oct 22, 2024 at 09:43:35AM +0100, Matthew Auld wrote:
> On 21/10/2024 22:18, Matthew Brost wrote:
> > Don't open code vmap of a BO, use ttm_bo_access helper which is safe for
> > non-contiguous BOs and non-visible BOs.
> > 
> > Suggested-by: Matthew Auld <matthew.auld@intel.com>
> > Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> 
> I guess needs fixes tag?
> 

I don't know enough about display but it is possible / likely that FB
BOs met the requirements that ttm_bo_kmap worked. Regardless safe this
way and I suppose I'll add a fixes tag here.

Matt

> With that,
> Reviewed-by: Matthew Auld <matthew.auld@intel.com>
> 
> > ---
> >   drivers/gpu/drm/xe/display/intel_bo.c | 25 +------------------------
> >   1 file changed, 1 insertion(+), 24 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/xe/display/intel_bo.c b/drivers/gpu/drm/xe/display/intel_bo.c
> > index 9f54fad0f1c0..43141964f6f2 100644
> > --- a/drivers/gpu/drm/xe/display/intel_bo.c
> > +++ b/drivers/gpu/drm/xe/display/intel_bo.c
> > @@ -40,31 +40,8 @@ int intel_bo_fb_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
> >   int intel_bo_read_from_page(struct drm_gem_object *obj, u64 offset, void *dst, int size)
> >   {
> >   	struct xe_bo *bo = gem_to_xe_bo(obj);
> > -	struct ttm_bo_kmap_obj map;
> > -	void *src;
> > -	bool is_iomem;
> > -	int ret;
> > -	ret = xe_bo_lock(bo, true);
> > -	if (ret)
> > -		return ret;
> > -
> > -	ret = ttm_bo_kmap(&bo->ttm, offset >> PAGE_SHIFT, 1, &map);
> > -	if (ret)
> > -		goto out_unlock;
> > -
> > -	offset &= ~PAGE_MASK;
> > -	src = ttm_kmap_obj_virtual(&map, &is_iomem);
> > -	src += offset;
> > -	if (is_iomem)
> > -		memcpy_fromio(dst, (void __iomem *)src, size);
> > -	else
> > -		memcpy(dst, src, size);
> > -
> > -	ttm_bo_kunmap(&map);
> > -out_unlock:
> > -	xe_bo_unlock(bo);
> > -	return ret;
> > +	return ttm_bo_access(&bo->ttm, offset, dst, size, 0);
> >   }
> >   struct intel_frontbuffer *intel_bo_get_frontbuffer(struct drm_gem_object *obj)