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From:   tanveer1.alam@intel.com
To:     gregkh@linuxfoundation.org, heikki.krogerus@linux.intel.com,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     tanveer1.alam@intel.com, abhijeet.rao@intel.com
Subject: [PATCH] usb: typec: mux: intel_pmc_mux: Add retry logic to a PMC command
Date:   Mon, 28 Mar 2022 16:21:37 +0530
Message-Id: <20220328105137.6223-1-tanveer1.alam@intel.com>
Precedence: bulk

From: Tanveer Alam <tanveer1.alam@intel.com>

There are few scenerio when PMC reports 'busy condition' and command
fail.

If PMC receives a high priority command while servicing a low priority
command then it discards the low priority command and start servicing
the high priority command. The lower priority command fail and driver
returns error. If the same command resend to the PMC then PMC latches
the command and service it accordingly.

Thus adds the retry logic for the PMC command.

Signed-off-by: Tanveer Alam <tanveer1.alam@intel.com>
---
 drivers/usb/typec/mux/intel_pmc_mux.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/typec/mux/intel_pmc_mux.c b/drivers/usb/typec/mux/intel_pmc_mux.c
index 2cdd22130834..da6b381ddf00 100644
--- a/drivers/usb/typec/mux/intel_pmc_mux.c
+++ b/drivers/usb/typec/mux/intel_pmc_mux.c
@@ -173,7 +173,7 @@ static int hsl_orientation(struct pmc_usb_port *port)
 	return port->orientation - 1;
 }
 
-static int pmc_usb_command(struct pmc_usb_port *port, u8 *msg, u32 len)
+static int pmc_usb_send_command(struct intel_scu_ipc_dev *ipc, u8 *msg, u32 len)
 {
 	u8 response[4];
 	u8 status_res;
@@ -184,7 +184,7 @@ static int pmc_usb_command(struct pmc_usb_port *port, u8 *msg, u32 len)
 	 * Status can be checked from the response message if the
 	 * function intel_scu_ipc_dev_command succeeds.
 	 */
-	ret = intel_scu_ipc_dev_command(port->pmc->ipc, PMC_USBC_CMD, 0, msg,
+	ret = intel_scu_ipc_dev_command(ipc, PMC_USBC_CMD, 0, msg,
 					len, response, sizeof(response));
 
 	if (ret)
@@ -203,6 +203,23 @@ static int pmc_usb_command(struct pmc_usb_port *port, u8 *msg, u32 len)
 	return 0;
 }
 
+static int pmc_usb_command(struct pmc_usb_port *port, u8 *msg, u32 len)
+{
+	int retry_count = 3;
+	int ret;
+
+	/*
+	 * If PMC is busy then retry the command once again
+	 */
+	while (retry_count--) {
+		ret = pmc_usb_send_command(port->pmc->ipc, msg, len);
+		if (ret != -EBUSY)
+			break;
+	}
+
+	return ret;
+}
+
 static int
 pmc_usb_mux_dp_hpd(struct pmc_usb_port *port, struct typec_displayport_data *dp)
 {
-- 
2.17.1