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, 3 deletions

diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index a168d64..4e10938 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -365,6 +365,7 @@ bool radeon_atombios_sideport_present(struct radeon_device *rdev);
  */
 struct radeon_scratch {
 	unsigned		num_reg;
+	uint32_t                reg_base;
 	bool			free[32];
 	uint32_t		reg[32];
 };
@@ -593,8 +594,13 @@ struct radeon_wb {
 	struct radeon_bo	*wb_obj;
 	volatile uint32_t	*wb;
 	uint64_t		gpu_addr;
+	bool                    enabled;
 };
 
+#define RADEON_WB_SCRATCH_OFFSET 0
+#define RADEON_WB_CP_RPTR_OFFSET 1024
+#define R600_WB_IH_WPTR_OFFSET   2048
+
 /**
  * struct radeon_pm - power management datas
  * @max_bandwidth:      maximum bandwidth the gpu has (MByte/s)
@@ -1340,6 +1346,9 @@ extern void radeon_update_bandwidth_info(struct radeon_device *rdev);
 extern void radeon_update_display_priority(struct radeon_device *rdev);
 extern bool radeon_boot_test_post_card(struct radeon_device *rdev);
 extern void radeon_scratch_init(struct radeon_device *rdev);
+extern void radeon_wb_fini(struct radeon_device *rdev);
+extern int radeon_wb_init(struct radeon_device *rdev);
+extern void radeon_wb_disable(struct radeon_device *rdev);
 extern void radeon_surface_init(struct radeon_device *rdev);
 extern int radeon_cs_parser_init(struct radeon_cs_parser *p, void *data);
 extern void radeon_legacy_set_clock_gating(struct radeon_device *rdev, int enable);
@@ -1424,9 +1433,6 @@ extern int r600_pcie_gart_init(struct radeon_device *rdev);
 extern void r600_pcie_gart_tlb_flush(struct radeon_device *rdev);
 extern int r600_ib_test(struct radeon_device *rdev);
 extern int r600_ring_test(struct radeon_device *rdev);
-extern void r600_wb_fini(struct radeon_device *rdev);
-extern int r600_wb_enable(struct radeon_device *rdev);
-extern void r600_wb_disable(struct radeon_device *rdev);
 extern void r600_scratch_init(struct radeon_device *rdev);
 extern int r600_blit_init(struct radeon_device *rdev);
 extern void r600_blit_fini(struct radeon_device *rdev);