Re: [PATCH 3/5] soundwire: qcom: wait for fifo to be empty before suspend

On 09/02/2023 15:23, Pierre-Louis Bossart wrote:

On 2/9/23 07:13, Srinivas Kandagatla wrote:

...

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.

For the suspend case that seems like a valid approach, but for bank switch don't we already have a bus->msg_lock mutex that will prevent the bank switch command from being sent before the other commands are handled?

All read/writes are fifo based, so writes could be still pending.

--srini

...

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 b2363839624c..465b2a2ef0d5 100644 --- a/drivers/soundwire/qcom.c +++ b/drivers/soundwire/qcom.c @@ -325,6 +325,32 @@ static int swrm_wait_for_wr_fifo_avail(struct qcom_swrm_ctrl *swrm) return 0; }

+static bool swrm_wait_for_wr_fifo_done(struct qcom_swrm_ctrl *swrm) +{

• u32 fifo_outstanding_cmds, value;
• int fifo_retry_count = SWR_OVERFLOW_RETRY_COUNT;
• /* Check for fifo overflow during write */
• swrm->reg_read(swrm, SWRM_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);
  

• 	swrm->reg_read(swrm, SWRM_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 *swrm, u8 cmd_data, u8 dev_addr, u16 reg_addr) {

@@ -356,6 +382,7 @@ static int qcom_swrm_cmd_fifo_wr_cmd(struct qcom_swrm_ctrl *swrm, u8 cmd_data, usleep_range(150, 155);

if (cmd_id == SWR_BROADCAST_CMD_ID) {

• swrm_wait_for_wr_fifo_done(swrm);
  

  /*
  • sleep for 10ms for MSM soundwire variant to allow broadcast
  • command to complete.

@@ -1122,6 +1149,7 @@ 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);

@@ -1558,6 +1586,7 @@ 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;