[PATCH v2 7/8] drm/i915: fixup the initial fb base on DG1

[Matthew Auld]

The offset we get looks to be the exact start of DSM, but the
inital_plane_vma expects the address to be relative.

v2(Ville):
  - The base is actually the pre-programmed GGTT address, which is then
    meant to 1:1 map to somewhere inside dsm. In the case of dgpu the
    base looks to just be some offset within lmem, but this also happens
    to be the exact dsm start, on dg1. Therefore we should only need to
    fudge the physical address, before allocating from stolen.
  - Bail if it's not located in dsm.

Signed-off-by: Matthew Auld <matthew.auld at intel.com>
Cc: Thomas Hellström <thomas.hellstrom at linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 .../drm/i915/display/intel_plane_initial.c    | 21 +++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_plane_initial.c b/drivers/gpu/drm/i915/display/intel_plane_initial.c
index f797fcef18fc..2aebde02ff57 100644
--- a/drivers/gpu/drm/i915/display/intel_plane_initial.c
+++ b/drivers/gpu/drm/i915/display/intel_plane_initial.c
@@ -50,7 +50,7 @@ initial_plane_vma(struct drm_i915_private *i915,
 	struct intel_memory_region *mem = i915->mm.stolen_region;
 	struct drm_i915_gem_object *obj;
 	struct i915_vma *vma;
-	u32 base, size;
+	u32 base, phys_base, size;
 	u64 pinctl;
 
 	if (!mem || plane_config->size == 0)
@@ -71,8 +71,25 @@ initial_plane_vma(struct drm_i915_private *i915,
 	    size * 2 > i915->stolen_usable_size)
 		return NULL;
 
+	/*
+	 * On discrete, it looks like the GGTT base address should 1:1 map to
+	 * somewhere in lmem. On DG1 for some reason this intersects with the
+	 * exact start of DSM(possibly due to small lmem size), in which case we
+	 * need to allocate it directly from stolen, which means fudging the
+	 * physical address to be relative to the start of DSM.  In such cases
+	 * we might also need to choose between initial fb vs fbc, if space is
+	 * limited.
+	 */
+	phys_base = base;
+	if (IS_DG1(i915)) {
+		if (WARN_ON(phys_base < i915->dsm.start))
+			return NULL;
+
+		phys_base -= i915->dsm.start;
+	}
+
 	obj = i915_gem_object_create_region_at(i915->mm.stolen_region,
-					       base, size, 0);
+					       phys_base, size, 0);
 	if (IS_ERR(obj))
 		return NULL;
 
-- 
2.34.1