drm/i915: turn on small BAR support

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>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220629174350.384910-13-matthew.auld@intel.com

diff --git a/drivers/gpu/drm/i915/gt/intel_region_lmem.c b/drivers/gpu/drm/i915/gt/intel_region_lmem.c
index d09b996a975944c0cbf78e9d96654c644bbdf12e..fa7b86f83e7b9d9bdc47e4a48aaa1fa4e11b2a48 100644 (file)
--- 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);
+
        return mem;
 
 err_region_put: