[PATCH v2 2/4] soundwire: qcom: wait for fifo to be empty before suspend

[Srinivas Kandagatla <srinivas.kandagatla@linaro.org>]

Wait for Fifo to be empty before going to suspend or before bank
switch happens. Just to make sure that all the reads/writes are done.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
---
 drivers/soundwire/qcom.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/drivers/soundwire/qcom.c b/drivers/soundwire/qcom.c
index 9440787e924b..adf025194a31 100644
--- a/drivers/soundwire/qcom.c
+++ b/drivers/soundwire/qcom.c
@@ -404,6 +404,32 @@ static int swrm_wait_for_wr_fifo_avail(struct qcom_swrm_ctrl *ctrl)
 	return 0;
 }
 
+static bool swrm_wait_for_wr_fifo_done(struct qcom_swrm_ctrl *ctrl)
+{
+	u32 fifo_outstanding_cmds, value;
+	int fifo_retry_count = SWR_OVERFLOW_RETRY_COUNT;
+
+	/* Check for fifo overflow during write */
+	ctrl->reg_read(ctrl, ctrl->reg_layout[SWRM_REG_CMD_FIFO_STATUS], &value);
+	fifo_outstanding_cmds = FIELD_GET(SWRM_WR_CMD_FIFO_CNT_MASK, value);
+
+	if (fifo_outstanding_cmds) {
+		while (fifo_retry_count) {
+			usleep_range(500, 510);
+			ctrl->reg_read(ctrl, ctrl->reg_layout[SWRM_REG_CMD_FIFO_STATUS], &value);
+			fifo_outstanding_cmds = FIELD_GET(SWRM_WR_CMD_FIFO_CNT_MASK, value);
+			fifo_retry_count--;
+			if (fifo_outstanding_cmds == 0)
+				return true;
+		}
+	} else {
+		return true;
+	}
+
+
+	return false;
+}
+
 static int qcom_swrm_cmd_fifo_wr_cmd(struct qcom_swrm_ctrl *ctrl, u8 cmd_data,
 				     u8 dev_addr, u16 reg_addr)
 {
@@ -434,6 +460,7 @@ static int qcom_swrm_cmd_fifo_wr_cmd(struct qcom_swrm_ctrl *ctrl, u8 cmd_data,
 		usleep_range(150, 155);
 
 	if (cmd_id == SWR_BROADCAST_CMD_ID) {
+		swrm_wait_for_wr_fifo_done(ctrl);
 		/*
 		 * sleep for 10ms for MSM soundwire variant to allow broadcast
 		 * command to complete.
@@ -1230,6 +1257,7 @@ static void qcom_swrm_shutdown(struct snd_pcm_substream *substream,
 {
 	struct qcom_swrm_ctrl *ctrl = dev_get_drvdata(dai->dev);
 
+	swrm_wait_for_wr_fifo_done(ctrl);
 	sdw_release_stream(ctrl->sruntime[dai->id]);
 	ctrl->sruntime[dai->id] = NULL;
 	pm_runtime_mark_last_busy(ctrl->dev);
@@ -1688,6 +1716,7 @@ static int __maybe_unused swrm_runtime_suspend(struct device *dev)
 	struct qcom_swrm_ctrl *ctrl = dev_get_drvdata(dev);
 	int ret;
 
+	swrm_wait_for_wr_fifo_done(ctrl);
 	if (!ctrl->clock_stop_not_supported) {
 		/* Mask bus clash interrupt */
 		ctrl->intr_mask &= ~SWRM_INTERRUPT_STATUS_MASTER_CLASH_DET;
-- 
2.21.0