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From:   Lucas Tanure <tanureal@opensource.cirrus.com>
To:     Michal Simek <michal.simek@xilinx.com>,
        Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
CC:     <linux-arm-kernel@lists.infradead.org>,
        <linux-i2c@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <patches@opensource.cirrus.com>,
        Lucas Tanure <tanureal@opensource.cirrus.com>
Subject: [PATCH v2] i2c: cadence: Increase timeout per message if necessary
Date:   Tue, 22 Mar 2022 15:50:31 +0000
Message-ID: <20220322155031.7942-1-tanureal@opensource.cirrus.com>
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Timeout as 1 second sets an upper limit on the length
of the transfer executed, but there is no maximum length
of a write or read message set in i2c_adapter_quirks for
this controller.

This upper limit affects devices that require sending
large firmware blobs over I2C.

To remove that limitation, calculate the minimal time
necessary, plus some wiggle room, for every message and
use it instead of the default one second, if more than
one second.

Signed-off-by: Lucas Tanure <tanureal@opensource.cirrus.com>
Acked-by: Michal Simek <michal.simek@xilinx.com>
---
 drivers/i2c/busses/i2c-cadence.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-cadence.c b/drivers/i2c/busses/i2c-cadence.c
index 805c77143a0f..b4c1ad19cdae 100644
--- a/drivers/i2c/busses/i2c-cadence.c
+++ b/drivers/i2c/busses/i2c-cadence.c
@@ -760,7 +760,7 @@ static void cdns_i2c_master_reset(struct i2c_adapter *adap)
 static int cdns_i2c_process_msg(struct cdns_i2c *id, struct i2c_msg *msg,
 		struct i2c_adapter *adap)
 {
-	unsigned long time_left;
+	unsigned long time_left, msg_timeout;
 	u32 reg;
 
 	id->p_msg = msg;
@@ -785,8 +785,16 @@ static int cdns_i2c_process_msg(struct cdns_i2c *id, struct i2c_msg *msg,
 	else
 		cdns_i2c_msend(id);
 
+	/* Minimal time to execute this message */
+	msg_timeout = msecs_to_jiffies((1000 * msg->len * BITS_PER_BYTE) / id->i2c_clk);
+	/* Plus some wiggle room */
+	msg_timeout += msecs_to_jiffies(500);
+
+	if (msg_timeout < adap->timeout)
+		msg_timeout = adap->timeout;
+
 	/* Wait for the signal of completion */
-	time_left = wait_for_completion_timeout(&id->xfer_done, adap->timeout);
+	time_left = wait_for_completion_timeout(&id->xfer_done, msg_timeout);
 	if (time_left == 0) {
 		cdns_i2c_master_reset(adap);
 		dev_err(id->adap.dev.parent,
-- 
2.35.1