[Intel-gfx] [PATCH] drm/i915: Fix display problems after resume

[Ville Syrjälä]

On Mon, Sep 12, 2022 at 02:19:57PM +0200, Thomas Hellström wrote:
> Commit 39a2bd34c933 ("drm/i915: Use the vma resource as argument for gtt
> binding / unbinding") introduced a regression that due to the vma resource
> tracking of the binding state, dpt ptes were not correctly repopulated.

Doesn't this mean all ggtt ptes weren't repopulated? So I'm
wondering how anything at all has been working?

> Fix this by clearing the vma resource state before repopulating.
> The state will subsequently be restored by the bind_vma operation.
> 
> Fixes: 39a2bd34c933 ("drm/i915: Use the vma resource as argument for gtt binding / unbinding")
> Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/gt/intel_ggtt.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_ggtt.c b/drivers/gpu/drm/i915/gt/intel_ggtt.c
> index 30cf5c3369d9..2049a00417af 100644
> --- a/drivers/gpu/drm/i915/gt/intel_ggtt.c
> +++ b/drivers/gpu/drm/i915/gt/intel_ggtt.c
> @@ -1275,10 +1275,16 @@ bool i915_ggtt_resume_vm(struct i915_address_space *vm)
>  			atomic_read(&vma->flags) & I915_VMA_BIND_MASK;
>  
>  		GEM_BUG_ON(!was_bound);
> -		if (!retained_ptes)
> +		if (!retained_ptes) {
> +			/*
> +			 * Clear the bound flags of the vma resource to allow
> +			 * ptes to be repopulated.
> +			 */
> +			vma->resource->bound_flags = 0;
>  			vma->ops->bind_vma(vm, NULL, vma->resource,
>  					   obj ? obj->cache_level : 0,
>  					   was_bound);
> +		}
>  		if (obj) { /* only used during resume => exclusive access */
>  			write_domain_objs |= fetch_and_zero(&obj->write_domain);
>  			obj->read_domains |= I915_GEM_DOMAIN_GTT;
> -- 
> 2.34.1

-- 
Ville Syrjälä
Intel