drm/msm: Add a parameter query for the number of ringbuffers

In order to manage ringbuffer priority to its fullest userspace
should know how many ringbuffers it has to work with. Add a
parameter to return the number of active rings.
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>

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

@@ -57,6 +57,9 @@ int adreno_get_param(struct msm_gpu *gpu, uint32_t param, uint64_t *value)
 			return ret;
 		}
 		return -EINVAL;
+	case MSM_PARAM_NR_RINGS:
+		*value = gpu->nr_rings;
+		return 0;
 	default:
 		DBG("%s: invalid param: %u", gpu->name, param);
 		return -EINVAL;

include/uapi/drm/msm_drm.h

@@ -73,6 +73,7 @@ struct drm_msm_timespec {
 #define MSM_PARAM_MAX_FREQ   0x04
 #define MSM_PARAM_TIMESTAMP  0x05
 #define MSM_PARAM_GMEM_BASE  0x06
+#define MSM_PARAM_NR_RINGS   0x07
 
 struct drm_msm_param {
 	__u32 pipe;           /* in, MSM_PIPE_x */