drm/msm/adreno: get CP_RPTR from register instead of shadow memory

As described in the downstream/kgsl driver:
Sometimes the RPTR shadow memory is unreliable causing timeouts
in adreno_idle().  Read it directly from the register instead.
Signed-off-by: Craig Stout <cstout@chromium.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/adreno/adreno_gpu.c

@@ -71,18 +71,15 @@ int adreno_hw_init(struct msm_gpu *gpu)
 	adreno_gpu_write(adreno_gpu, REG_ADRENO_CP_RB_CNTL,
 			/* size is log2(quad-words): */
 			AXXX_CP_RB_CNTL_BUFSZ(ilog2(gpu->rb->size / 8)) |
-			AXXX_CP_RB_CNTL_BLKSZ(ilog2(RB_BLKSIZE / 8)));
+			AXXX_CP_RB_CNTL_BLKSZ(ilog2(RB_BLKSIZE / 8)) |
+			(adreno_is_a430(adreno_gpu) ? AXXX_CP_RB_CNTL_NO_UPDATE : 0));
 
 	/* Setup ringbuffer address: */
 	adreno_gpu_write(adreno_gpu, REG_ADRENO_CP_RB_BASE, gpu->rb_iova);
-	adreno_gpu_write(adreno_gpu, REG_ADRENO_CP_RB_RPTR_ADDR,
-			rbmemptr(adreno_gpu, rptr));
 
-	/* Setup scratch/timestamp: */
-	adreno_gpu_write(adreno_gpu, REG_ADRENO_SCRATCH_ADDR,
-			rbmemptr(adreno_gpu, fence));
-
-	adreno_gpu_write(adreno_gpu, REG_ADRENO_SCRATCH_UMSK, 0x1);
+	if (!adreno_is_a430(adreno_gpu))
+		adreno_gpu_write(adreno_gpu, REG_ADRENO_CP_RB_RPTR_ADDR,
+						rbmemptr(adreno_gpu, rptr));
 
 	return 0;
 }
@@ -92,6 +89,16 @@ static uint32_t get_wptr(struct msm_ringbuffer *ring)
 	return ring->cur - ring->start;
 }
 
+/* Use this helper to read rptr, since a430 doesn't update rptr in memory */
+static uint32_t get_rptr(struct adreno_gpu *adreno_gpu)
+{
+	if (adreno_is_a430(adreno_gpu))
+		return adreno_gpu->memptrs->rptr = adreno_gpu_read(
+			adreno_gpu, REG_ADRENO_CP_RB_RPTR);
+	else
+		return adreno_gpu->memptrs->rptr;
+}
+
 uint32_t adreno_last_fence(struct msm_gpu *gpu)
 {
 	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
@@ -220,9 +227,12 @@ void adreno_idle(struct msm_gpu *gpu)
 {
 	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
 	uint32_t wptr = get_wptr(gpu->rb);
+	int ret;
 
 	/* wait for CP to drain ringbuffer: */
-	if (spin_until(adreno_gpu->memptrs->rptr == wptr))
+	ret = spin_until(get_rptr(adreno_gpu) == wptr);
+
+	if (ret)
 		DRM_ERROR("%s: timeout waiting to drain ringbuffer!\n", gpu->name);
 
 	/* TODO maybe we need to reset GPU here to recover from hang? */
@@ -241,7 +251,7 @@ void adreno_show(struct msm_gpu *gpu, struct seq_file *m)
 
 	seq_printf(m, "fence:    %d/%d\n", adreno_gpu->memptrs->fence,
 			gpu->submitted_fence);
-	seq_printf(m, "rptr:     %d\n", adreno_gpu->memptrs->rptr);
+	seq_printf(m, "rptr:     %d\n", get_rptr(adreno_gpu));
 	seq_printf(m, "wptr:     %d\n", adreno_gpu->memptrs->wptr);
 	seq_printf(m, "rb wptr:  %d\n", get_wptr(gpu->rb));
 
@@ -282,7 +292,7 @@ void adreno_dump_info(struct msm_gpu *gpu)
 
 	printk("fence:    %d/%d\n", adreno_gpu->memptrs->fence,
 			gpu->submitted_fence);
-	printk("rptr:     %d\n", adreno_gpu->memptrs->rptr);
+	printk("rptr:     %d\n", get_rptr(adreno_gpu));
 	printk("wptr:     %d\n", adreno_gpu->memptrs->wptr);
 	printk("rb wptr:  %d\n", get_wptr(gpu->rb));
 
@@ -317,7 +327,7 @@ static uint32_t ring_freewords(struct msm_gpu *gpu)
 	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
 	uint32_t size = gpu->rb->size / 4;
 	uint32_t wptr = get_wptr(gpu->rb);
-	uint32_t rptr = adreno_gpu->memptrs->rptr;
+	uint32_t rptr = get_rptr(adreno_gpu);
 	return (rptr + (size - 1) - wptr) % size;
 }