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, 10 insertions, 5 deletions

diff --git a/drivers/gpu/drm/radeon/rv770.c b/drivers/gpu/drm/radeon/rv770.c
index bc2beb7d35e..ff1cc58920c 100644
--- a/drivers/gpu/drm/radeon/rv770.c
+++ b/drivers/gpu/drm/radeon/rv770.c
@@ -268,6 +268,7 @@ static void rv770_mc_program(struct radeon_device *rdev)
 void r700_cp_stop(struct radeon_device *rdev)
 {
 	WREG32(CP_ME_CNTL, (CP_ME_HALT | CP_PFP_HALT));
+	WREG32(SCRATCH_UMSK, 0);
 }
 
 static int rv770_cp_load_microcode(struct radeon_device *rdev)
@@ -1029,6 +1030,11 @@ static int rv770_startup(struct radeon_device *rdev)
 		dev_warn(rdev->dev, "failed blitter (%d) falling back to memcpy\n", r);
 	}
 
+	/* allocate wb buffer */
+	r = radeon_wb_init(rdev);
+	if (r)
+		return r;
+
 	/* Enable IRQ */
 	r = r600_irq_init(rdev);
 	if (r) {
@@ -1047,8 +1053,7 @@ static int rv770_startup(struct radeon_device *rdev)
 	r = r600_cp_resume(rdev);
 	if (r)
 		return r;
-	/* write back buffer are not vital so don't worry about failure */
-	r600_wb_enable(rdev);
+
 	return 0;
 }
 
@@ -1094,7 +1099,7 @@ int rv770_suspend(struct radeon_device *rdev)
 	r700_cp_stop(rdev);
 	rdev->cp.ready = false;
 	r600_irq_suspend(rdev);
-	r600_wb_disable(rdev);
+	radeon_wb_disable(rdev);
 	rv770_pcie_gart_disable(rdev);
 	/* unpin shaders bo */
 	if (rdev->r600_blit.shader_obj) {
@@ -1189,8 +1194,8 @@ int rv770_init(struct radeon_device *rdev)
 	if (r) {
 		dev_err(rdev->dev, "disabling GPU acceleration\n");
 		r700_cp_fini(rdev);
-		r600_wb_fini(rdev);
 		r600_irq_fini(rdev);
+		radeon_wb_fini(rdev);
 		radeon_irq_kms_fini(rdev);
 		rv770_pcie_gart_fini(rdev);
 		rdev->accel_working = false;
@@ -1222,8 +1227,8 @@ void rv770_fini(struct radeon_device *rdev)
 {
 	r600_blit_fini(rdev);
 	r700_cp_fini(rdev);
-	r600_wb_fini(rdev);
 	r600_irq_fini(rdev);
+	radeon_wb_fini(rdev);
 	radeon_irq_kms_fini(rdev);
 	rv770_pcie_gart_fini(rdev);
 	rv770_vram_scratch_fini(rdev);