drm/radeon: update rptr saving logic for memory buffers

Add support for using memory buffers rather than
scratch registers.  Some rings may not be able to
write to scratch registers.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>

drivers/gpu/drm/radeon/evergreen.c

@@ -1364,17 +1364,25 @@ void evergreen_mc_program(struct radeon_device *rdev)
 void evergreen_ring_ib_execute(struct radeon_device *rdev, struct radeon_ib *ib)
 {
 	struct radeon_ring *ring = &rdev->ring[ib->ring];
+	u32 next_rptr;
 
 	/* set to DX10/11 mode */
 	radeon_ring_write(ring, PACKET3(PACKET3_MODE_CONTROL, 0));
 	radeon_ring_write(ring, 1);
 
 	if (ring->rptr_save_reg) {
-		uint32_t next_rptr = ring->wptr + 3 + 4;
+		next_rptr = ring->wptr + 3 + 4;
 		radeon_ring_write(ring, PACKET3(PACKET3_SET_CONFIG_REG, 1));
 		radeon_ring_write(ring, ((ring->rptr_save_reg - 
 					  PACKET3_SET_CONFIG_REG_START) >> 2));
 		radeon_ring_write(ring, next_rptr);
+	} else if (rdev->wb.enabled) {
+		next_rptr = ring->wptr + 5 + 4;
+		radeon_ring_write(ring, PACKET3(PACKET3_MEM_WRITE, 3));
+		radeon_ring_write(ring, ring->next_rptr_gpu_addr & 0xfffffffc);
+		radeon_ring_write(ring, (upper_32_bits(ring->next_rptr_gpu_addr) & 0xff) | (1 << 18));
+		radeon_ring_write(ring, next_rptr);
+		radeon_ring_write(ring, 0);
 	}
 
 	radeon_ring_write(ring, PACKET3(PACKET3_INDIRECT_BUFFER, 2));

drivers/gpu/drm/radeon/r600.c

@@ -2163,10 +2163,12 @@ void r600_ring_init(struct radeon_device *rdev, struct radeon_ring *ring, unsign
 	ring->ring_size = ring_size;
 	ring->align_mask = 16 - 1;
 
-	r = radeon_scratch_get(rdev, &ring->rptr_save_reg);
-	if (r) {
-		DRM_ERROR("failed to get scratch reg for rptr save (%d).\n", r);
-		ring->rptr_save_reg = 0;
+	if (radeon_ring_supports_scratch_reg(rdev, ring)) {
+		r = radeon_scratch_get(rdev, &ring->rptr_save_reg);
+		if (r) {
+			DRM_ERROR("failed to get scratch reg for rptr save (%d).\n", r);
+			ring->rptr_save_reg = 0;
+		}
 	}
 }
 
@@ -2576,13 +2578,21 @@ void r600_fini(struct radeon_device *rdev)
 void r600_ring_ib_execute(struct radeon_device *rdev, struct radeon_ib *ib)
 {
 	struct radeon_ring *ring = &rdev->ring[ib->ring];
+	u32 next_rptr;
 
 	if (ring->rptr_save_reg) {
-		uint32_t next_rptr = ring->wptr + 3 + 4;
+		next_rptr = ring->wptr + 3 + 4;
 		radeon_ring_write(ring, PACKET3(PACKET3_SET_CONFIG_REG, 1));
 		radeon_ring_write(ring, ((ring->rptr_save_reg -
 					 PACKET3_SET_CONFIG_REG_OFFSET) >> 2));
 		radeon_ring_write(ring, next_rptr);
+	} else if (rdev->wb.enabled) {
+		next_rptr = ring->wptr + 5 + 4;
+		radeon_ring_write(ring, PACKET3(PACKET3_MEM_WRITE, 3));
+		radeon_ring_write(ring, ring->next_rptr_gpu_addr & 0xfffffffc);
+		radeon_ring_write(ring, (upper_32_bits(ring->next_rptr_gpu_addr) & 0xff) | (1 << 18));
+		radeon_ring_write(ring, next_rptr);
+		radeon_ring_write(ring, 0);
 	}
 
 	radeon_ring_write(ring, PACKET3(PACKET3_INDIRECT_BUFFER, 2));

drivers/gpu/drm/radeon/radeon.h

@@ -623,6 +623,8 @@ struct radeon_ring {
 	unsigned		rptr_offs;
 	unsigned		rptr_reg;
 	unsigned		rptr_save_reg;
+	u64			next_rptr_gpu_addr;
+	volatile u32		*next_rptr_cpu_addr;
 	unsigned		wptr;
 	unsigned		wptr_old;
 	unsigned		wptr_reg;
@@ -758,6 +760,8 @@ int radeon_ib_pool_init(struct radeon_device *rdev);
 void radeon_ib_pool_fini(struct radeon_device *rdev);
 int radeon_ib_ring_tests(struct radeon_device *rdev);
 /* Ring access between begin & end cannot sleep */
+bool radeon_ring_supports_scratch_reg(struct radeon_device *rdev,
+				      struct radeon_ring *ring);
 void radeon_ring_free_size(struct radeon_device *rdev, struct radeon_ring *cp);
 int radeon_ring_alloc(struct radeon_device *rdev, struct radeon_ring *cp, unsigned ndw);
 int radeon_ring_lock(struct radeon_device *rdev, struct radeon_ring *cp, unsigned ndw);
@@ -871,6 +875,7 @@ struct radeon_wb {
 };
 
 #define RADEON_WB_SCRATCH_OFFSET 0
+#define RADEON_WB_RING0_NEXT_RPTR 256
 #define RADEON_WB_CP_RPTR_OFFSET 1024
 #define RADEON_WB_CP1_RPTR_OFFSET 1280
 #define RADEON_WB_CP2_RPTR_OFFSET 1536

drivers/gpu/drm/radeon/radeon_ring.c

@@ -207,6 +207,19 @@ void radeon_ring_write(struct radeon_ring *ring, uint32_t v)
 	ring->ring_free_dw--;
 }
 
+bool radeon_ring_supports_scratch_reg(struct radeon_device *rdev,
+				      struct radeon_ring *ring)
+{
+	switch (ring->idx) {
+	case RADEON_RING_TYPE_GFX_INDEX:
+	case CAYMAN_RING_TYPE_CP1_INDEX:
+	case CAYMAN_RING_TYPE_CP2_INDEX:
+		return true;
+	default:
+		return false;
+	}
+}
+
 void radeon_ring_free_size(struct radeon_device *rdev, struct radeon_ring *ring)
 {
 	u32 rptr;
@@ -372,7 +385,7 @@ unsigned radeon_ring_backup(struct radeon_device *rdev, struct radeon_ring *ring
 	mutex_lock(&rdev->ring_lock);
 	*data = NULL;
 
-	if (ring->ring_obj == NULL || !ring->rptr_save_reg) {
+	if (ring->ring_obj == NULL) {
 		mutex_unlock(&rdev->ring_lock);
 		return 0;
 	}
@@ -384,7 +397,16 @@ unsigned radeon_ring_backup(struct radeon_device *rdev, struct radeon_ring *ring
 	}
 
 	/* calculate the number of dw on the ring */
-	ptr = RREG32(ring->rptr_save_reg);
+	if (ring->rptr_save_reg)
+		ptr = RREG32(ring->rptr_save_reg);
+	else if (rdev->wb.enabled)
+		ptr = le32_to_cpu(*ring->next_rptr_cpu_addr);
+	else {
+		/* no way to read back the next rptr */
+		mutex_unlock(&rdev->ring_lock);
+		return 0;
+	}
+
 	size = ring->wptr + (ring->ring_size / 4);
 	size -= ptr;
 	size &= ring->ptr_mask;
@@ -478,6 +500,11 @@ int radeon_ring_init(struct radeon_device *rdev, struct radeon_ring *ring, unsig
 	}
 	ring->ptr_mask = (ring->ring_size / 4) - 1;
 	ring->ring_free_dw = ring->ring_size / 4;
+	if (rdev->wb.enabled) {
+		u32 index = RADEON_WB_RING0_NEXT_RPTR + (ring->idx * 4);
+		ring->next_rptr_gpu_addr = rdev->wb.gpu_addr + index;
+		ring->next_rptr_cpu_addr = &rdev->wb.wb[index/4];
+	}
 	if (radeon_debugfs_ring_init(rdev, ring)) {
 		DRM_ERROR("Failed to register debugfs file for rings !\n");
 	}

drivers/gpu/drm/radeon/si.c

@@ -1772,12 +1772,20 @@ void si_ring_ib_execute(struct radeon_device *rdev, struct radeon_ib *ib)
 
 		header = PACKET3(PACKET3_INDIRECT_BUFFER_CONST, 2);
 	} else {
+		u32 next_rptr;
 		if (ring->rptr_save_reg) {
-			uint32_t next_rptr = ring->wptr + 3 + 4 + 8;
+			next_rptr = ring->wptr + 3 + 4 + 8;
 			radeon_ring_write(ring, PACKET3(PACKET3_SET_CONFIG_REG, 1));
 			radeon_ring_write(ring, ((ring->rptr_save_reg -
 						  PACKET3_SET_CONFIG_REG_START) >> 2));
 			radeon_ring_write(ring, next_rptr);
+		} else if (rdev->wb.enabled) {
+			next_rptr = ring->wptr + 5 + 4 + 8;
+			radeon_ring_write(ring, PACKET3(PACKET3_WRITE_DATA, 3));
+			radeon_ring_write(ring, (1 << 8));
+			radeon_ring_write(ring, ring->next_rptr_gpu_addr & 0xfffffffc);
+			radeon_ring_write(ring, upper_32_bits(ring->next_rptr_gpu_addr) & 0xffffffff);
+			radeon_ring_write(ring, next_rptr);
 		}
 
 		header = PACKET3(PACKET3_INDIRECT_BUFFER, 2);