[PATCH v3 08/16] drm/i915: Fix region start during initial plane readout

[Shankar, Uma]

> -----Original Message-----
> From: Intel-gfx <intel-gfx-bounces at lists.freedesktop.org> On Behalf Of Ville
> Syrjala
> Sent: Tuesday, January 16, 2024 1:26 PM
> To: intel-gfx at lists.freedesktop.org
> Subject: [PATCH v3 08/16] drm/i915: Fix region start during initial plane readout
> 
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> On MTL the stolen region starts at offset 8MiB from the start of LMEMBAR. The
> dma addresses are thus also offset by 8MiB. However the mm_node/etc. is zero
> based, and i915_pages_create_for_stolen() will add the appropriate region.start
> into the sg dma address. So when we do the readout we need to convert the dma
> address read from the PTE to be zero based as well.
> 
> Note that currently we don't take this path on MTL, but we should and thus this
> needs to be fixed. For lmem this works correctly already as the lmem
> region.start==0.
> 
> While at it let's also make sure the address points to somewhere within the
> memory region. We don't need to check the size as
> i915_gem_object_create_region_at() should later fail if the object size exceeds
> the region size.

Looks Good to me.
Reviewed-by: Uma Shankar <uma.shankar at intel.com>

> Cc: Paz Zcharya <pazz at chromium.org>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_plane_initial.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_plane_initial.c
> b/drivers/gpu/drm/i915/display/intel_plane_initial.c
> index ffc92b18fcf5..db594ccf0323 100644
> --- a/drivers/gpu/drm/i915/display/intel_plane_initial.c
> +++ b/drivers/gpu/drm/i915/display/intel_plane_initial.c
> @@ -79,16 +79,18 @@ initial_plane_vma(struct drm_i915_private *i915,
>  		 * We don't currently expect this to ever be placed in the
>  		 * stolen portion.
>  		 */
> -		if (phys_base >= resource_size(&mem->region)) {
> +		if (phys_base < mem->region.start || phys_base > mem-
> >region.end) {
>  			drm_err(&i915->drm,
> -				"Initial plane programming using invalid range,
> phys_base=%pa\n",
> -				&phys_base);
> +				"Initial plane programming using invalid range,
> phys_base=%pa (%s [%pa-%pa])\n",
> +				&phys_base, mem->region.name, &mem-
> >region.start,
> +&mem->region.end);
>  			return NULL;
>  		}
> 
>  		drm_dbg(&i915->drm,
>  			"Using phys_base=%pa, based on initial plane
> programming\n",
>  			&phys_base);
> +
> +		phys_base -= mem->region.start;
>  	} else {
>  		phys_base = base;
>  		mem = i915->mm.stolen_region;
> --
> 2.41.0