drm/radeon/kms: enable writeback (v2)

When writeback is enabled, the GPU shadows writes to certain
registers into a buffer in memory.  The driver can then read
the values from the shadow rather than reading back from the
register across the bus.  Writeback can be disabled by setting
the no_wb module param to 1.

On r6xx/r7xx/evergreen, the following registers are shadowed:
- CP scratch registers
- CP read pointer
- IH write pointer
On r1xx-rr5xx, the following registers are shadowed:
- CP scratch registers
- CP read pointer

v2:
- Combine wb patches for r6xx-evergreen and r1xx-r5xx
- Writeback is disabled on AGP boards since it tends to be
unreliable on AGP using the gart.
- Check radeon_wb_init return values properly.

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 9 insertions, 6 deletions

diff --git a/drivers/gpu/drm/radeon/rs600.c b/drivers/gpu/drm/radeon/rs600.c
index cc05b230d7ef..8d8359a5d459 100644
--- a/drivers/gpu/drm/radeon/rs600.c
+++ b/drivers/gpu/drm/radeon/rs600.c
@@ -795,6 +795,12 @@ static int rs600_startup(struct radeon_device *rdev)
         r = rs600_gart_enable(rdev);
         if (r)
                 return r;
+
+        /* allocate wb buffer */
+        r = radeon_wb_init(rdev);
+        if (r)
+                return r;
+
         /* Enable IRQ */
         rs600_irq_set(rdev);
         rdev->config.r300.hdp_cntl = RREG32(RADEON_HOST_PATH_CNTL);
@@ -804,9 +810,6 @@ static int rs600_startup(struct radeon_device *rdev)
                 dev_err(rdev->dev, "failled initializing CP (%d).\n", r);
                 return r;
         }
-        r = r100_wb_init(rdev);
-        if (r)
-                dev_err(rdev->dev, "failled initializing WB (%d).\n", r);
         r = r100_ib_init(rdev);
         if (r) {
                 dev_err(rdev->dev, "failled initializing IB (%d).\n", r);
@@ -847,7 +850,7 @@ int rs600_suspend(struct radeon_device *rdev)
 {
         r600_audio_fini(rdev);
         r100_cp_disable(rdev);
-        r100_wb_disable(rdev);
+        radeon_wb_disable(rdev);
         rs600_irq_disable(rdev);
         rs600_gart_disable(rdev);
         return 0;
@@ -857,7 +860,7 @@ void rs600_fini(struct radeon_device *rdev)
 {
         r600_audio_fini(rdev);
         r100_cp_fini(rdev);
-        r100_wb_fini(rdev);
+        radeon_wb_fini(rdev);
         r100_ib_fini(rdev);
         radeon_gem_fini(rdev);
         rs600_gart_fini(rdev);
@@ -931,7 +934,7 @@ int rs600_init(struct radeon_device *rdev)
                 /* Somethings want wront with the accel init stop accel */
                 dev_err(rdev->dev, "Disabling GPU acceleration\n");
                 r100_cp_fini(rdev);
-                r100_wb_fini(rdev);
+                radeon_wb_fini(rdev);
                 r100_ib_fini(rdev);
                 rs600_gart_fini(rdev);
                 radeon_irq_kms_fini(rdev);