linux-kernel - [PATCH 2/6] soundwire: qcom: check for outanding writes before doing a read

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Date:   Wed, 26 Oct 2022 12:02:06 +0100
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     vkoul@...nel.org, yung-chuan.liao@...ux.intel.com
Cc:     andersson@...nel.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org,
        pierre-louis.bossart@...ux.intel.com, sanyog.r.kale@...el.com,
        srinivas.kandagatla@...aro.org, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        alsa-devel@...a-project.org
Subject: [PATCH 2/6] soundwire: qcom: check for outanding writes before doing a read

Reading will increase the fifo count, so check for outstanding cmd wrt.
write fifo depth to avoid overflow as read will also increase
write fifo cnt.

Fixes: a661308c34de ("soundwire: qcom: wait for fifo space to be available before read/write")
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
---
 drivers/soundwire/qcom.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/soundwire/qcom.c b/drivers/soundwire/qcom.c
index 8f1a1eb017a2..cee2b2223141 100644
--- a/drivers/soundwire/qcom.c
+++ b/drivers/soundwire/qcom.c
@@ -380,6 +380,12 @@ static int qcom_swrm_cmd_fifo_rd_cmd(struct qcom_swrm_ctrl *swrm,
 
 	val = swrm_get_packed_reg_val(&swrm->rcmd_id, len, dev_addr, reg_addr);
 
+	/*
+	 * Check for outstanding cmd wrt. write fifo depth to avoid
+	 * overflow as read will also increase write fifo cnt.
+	 */
+	swrm_wait_for_wr_fifo_avail(swrm);
+
 	/* wait for FIFO RD to complete to avoid overflow */
 	usleep_range(100, 105);
 	swrm->reg_write(swrm, SWRM_CMD_FIFO_RD_CMD, val);
-- 
2.21.0