drm/radeon: update comments to clarify VM setup (v2)

The actual set up and assignment of VM page tables
is done on the fly in radeon_gart.c.

v2: update vm size comments

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>

3 files changed, 12 insertions, 3 deletions

diff --git a/drivers/gpu/drm/radeon/ni.c b/drivers/gpu/drm/radeon/ni.c
index 8bcb554ea0c5..83dc0852d5c9 100644
--- a/drivers/gpu/drm/radeon/ni.c
+++ b/drivers/gpu/drm/radeon/ni.c
@@ -770,6 +770,10 @@ static int cayman_pcie_gart_enable(struct radeon_device *rdev)
         WREG32(0x15DC, 0);
 
         /* empty context1-7 */
+        /* Assign the pt base to something valid for now; the pts used for
+         * the VMs are determined by the application and setup and assigned
+         * on the fly in the vm part of radeon_gart.c
+         */
         for (i = 1; i < 8; i++) {
                 WREG32(VM_CONTEXT0_PAGE_TABLE_START_ADDR + (i << 2), 0);
                 WREG32(VM_CONTEXT0_PAGE_TABLE_END_ADDR + (i << 2), 0);
diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
index 64a42647f08a..bd13ca09eb62 100644
--- a/drivers/gpu/drm/radeon/radeon_device.c
+++ b/drivers/gpu/drm/radeon/radeon_device.c
@@ -1018,6 +1018,10 @@ int radeon_device_init(struct radeon_device *rdev,
                 return r;
         /* initialize vm here */
         mutex_init(&rdev->vm_manager.lock);
+        /* Adjust VM size here.
+         * Currently set to 4GB ((1 << 20) 4k pages).
+         * Max GPUVM size for cayman and SI is 40 bits.
+         */
         rdev->vm_manager.max_pfn = 1 << 20;
         INIT_LIST_HEAD(&rdev->vm_manager.lru_vm);
 
diff --git a/drivers/gpu/drm/radeon/si.c b/drivers/gpu/drm/radeon/si.c
index f79633a036c3..df8dd7701643 100644
--- a/drivers/gpu/drm/radeon/si.c
+++ b/drivers/gpu/drm/radeon/si.c
@@ -2407,12 +2407,13 @@ static int si_pcie_gart_enable(struct radeon_device *rdev)
         WREG32(0x15DC, 0);
 
         /* empty context1-15 */
-        /* FIXME start with 4G, once using 2 level pt switch to full
-         * vm size space
-         */
         /* set vm size, must be a multiple of 4 */
         WREG32(VM_CONTEXT1_PAGE_TABLE_START_ADDR, 0);
         WREG32(VM_CONTEXT1_PAGE_TABLE_END_ADDR, rdev->vm_manager.max_pfn);
+        /* Assign the pt base to something valid for now; the pts used for
+         * the VMs are determined by the application and setup and assigned
+         * on the fly in the vm part of radeon_gart.c
+         */
         for (i = 1; i < 16; i++) {
                 if (i < 8)
                         WREG32(VM_CONTEXT0_PAGE_TABLE_BASE_ADDR + (i << 2),