[media] s5p-mfc: support MIN_BUFFERS query for encoder

Add V4L2_CID_MIN_BUFFERS_FOR_OUTPUT query for encoder.
Once mfc encoder state is HEAD_PARSED, which is sequence
header produced, dpb_count is avaialable. Let user space
query this value.

Signed-off-by: Kiran AVND <avnd.kiran@samsung.com>
Signed-off-by: Arun Kumar K <arun.kk@samsung.com>
Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/platform/s5p-mfc/s5p_mfc_enc.c

@@ -690,6 +690,16 @@ static struct mfc_control controls[] = {
 		.step = 1,
 		.default_value = 0,
 	},
+	{
+		.id = V4L2_CID_MIN_BUFFERS_FOR_OUTPUT,
+		.type = V4L2_CTRL_TYPE_INTEGER,
+		.name = "Minimum number of output bufs",
+		.minimum = 1,
+		.maximum = 32,
+		.step = 1,
+		.default_value = 1,
+		.is_volatile = 1,
+	},
 };
 
 #define NUM_CTRLS ARRAY_SIZE(controls)
@@ -1624,8 +1634,40 @@ static int s5p_mfc_enc_s_ctrl(struct v4l2_ctrl *ctrl)
 	return ret;
 }
 
+static int s5p_mfc_enc_g_v_ctrl(struct v4l2_ctrl *ctrl)
+{
+	struct s5p_mfc_ctx *ctx = ctrl_to_ctx(ctrl);
+	struct s5p_mfc_dev *dev = ctx->dev;
+
+	switch (ctrl->id) {
+	case V4L2_CID_MIN_BUFFERS_FOR_OUTPUT:
+		if (ctx->state >= MFCINST_HEAD_PARSED &&
+		    ctx->state < MFCINST_ABORT) {
+			ctrl->val = ctx->pb_count;
+			break;
+		} else if (ctx->state != MFCINST_INIT) {
+			v4l2_err(&dev->v4l2_dev, "Encoding not initialised\n");
+			return -EINVAL;
+		}
+		/* Should wait for the header to be produced */
+		s5p_mfc_clean_ctx_int_flags(ctx);
+		s5p_mfc_wait_for_done_ctx(ctx,
+				S5P_MFC_R2H_CMD_SEQ_DONE_RET, 0);
+		if (ctx->state >= MFCINST_HEAD_PARSED &&
+		    ctx->state < MFCINST_ABORT) {
+			ctrl->val = ctx->pb_count;
+		} else {
+			v4l2_err(&dev->v4l2_dev, "Encoding not initialised\n");
+			return -EINVAL;
+		}
+		break;
+	}
+	return 0;
+}
+
 static const struct v4l2_ctrl_ops s5p_mfc_enc_ctrl_ops = {
 	.s_ctrl = s5p_mfc_enc_s_ctrl,
+	.g_volatile_ctrl = s5p_mfc_enc_g_v_ctrl,
 };
 
 static int vidioc_s_parm(struct file *file, void *priv,