Re: [PATCH v3 13/13] drm/i915: turn on small BAR support

["Thomas Hellström" <thomas.hellstrom@linux.intel.com>]

On 6/29/22 14:14, Matthew Auld wrote:
> With the uAPI in place we should now have enough in place to ensure a
> working system on small BAR configurations.
>
> v2: (Nirmoy & Thomas):
>    - s/full BAR/Resizable BAR/ which is hopefully more easily
>      understood by users.
>
> Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
> Cc: Jon Bloomfield <jon.bloomfield@intel.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Jordan Justen <jordan.l.justen@intel.com>
> Cc: Kenneth Graunke <kenneth@whitecape.org>
> Cc: Akeem G Abodunrin <akeem.g.abodunrin@intel.com>
> ---
>   drivers/gpu/drm/i915/gt/intel_region_lmem.c | 10 ++++------
>   1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_region_lmem.c b/drivers/gpu/drm/i915/gt/intel_region_lmem.c
> index d09b996a9759..fa7b86f83e7b 100644
> --- a/drivers/gpu/drm/i915/gt/intel_region_lmem.c
> +++ b/drivers/gpu/drm/i915/gt/intel_region_lmem.c
> @@ -112,12 +112,6 @@ static struct intel_memory_region *setup_lmem(struct intel_gt *gt)
>   		flat_ccs_base = intel_gt_mcr_read_any(gt, XEHP_FLAT_CCS_BASE_ADDR);
>   		flat_ccs_base = (flat_ccs_base >> XEHP_CCS_BASE_SHIFT) * SZ_64K;
>   
> -		/* FIXME: Remove this when we have small-bar enabled */
> -		if (pci_resource_len(pdev, 2) < lmem_size) {
> -			drm_err(&i915->drm, "System requires small-BAR support, which is currently unsupported on this kernel\n");
> -			return ERR_PTR(-EINVAL);
> -		}
> -
>   		if (GEM_WARN_ON(lmem_size < flat_ccs_base))
>   			return ERR_PTR(-EIO);
>   
> @@ -170,6 +164,10 @@ static struct intel_memory_region *setup_lmem(struct intel_gt *gt)
>   	drm_info(&i915->drm, "Local memory available: %pa\n",
>   		 &lmem_size);
>   
> +	if (io_size < lmem_size)
> +		drm_info(&i915->drm, "Using a reduced BAR size of %lluMiB. Consider enabling 'Resizable BAR' or similar, if available in the BIOS.\n",
> +			 (u64)io_size >> 20);
> +

Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>