[linux-yocto] [kernel v5.2/standard/xlnx-soc][PATCH 1/2] i2c: cadence: do not clear bus_hold_flag in mrecv

[quanyang.wang at windriver.com]

From: Quanyang Wang <quanyang.wang at windriver.com>

When using i2c_smbus_read_byte_data to read one byte from a
slave device, because of the commit d358def70688
("i2c: cadence: Fix the hold bit setting"), the transaction becomes:

S Addr Wr [A] Comm [A] P S Addr Rd [A] [Data] NA P
                       ^
                CR_HOLD bit as 0

This will result that the read operation fails and will read "0xff" from
the slave device. In the SMBus protocol stipulates that it must follow that
command with a repeated START condition as below:

S Addr Wr [A] Comm [A] Sr Addr Rd [A] [Data] NA P

So keep CR_HOLD bit to be 1 to make sure that the read operation begins
with a Sr (repeated START) but not a STOP followed by START.

Signed-off-by: Quanyang Wang <quanyang.wang at windriver.com>
---
 drivers/i2c/busses/i2c-cadence.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-cadence.c b/drivers/i2c/busses/i2c-cadence.c
index 6b011931e090..d9493914be15 100644
--- a/drivers/i2c/busses/i2c-cadence.c
+++ b/drivers/i2c/busses/i2c-cadence.c
@@ -626,8 +626,6 @@ static void cdns_i2c_mrecv(struct cdns_i2c *id)
 	 */
 	if ((id->recv_count > CDNS_I2C_FIFO_DEPTH)  || id->bus_hold_flag)
 		ctrl_reg |= CDNS_I2C_CR_HOLD;
-	else
-		ctrl_reg = ctrl_reg & ~CDNS_I2C_CR_HOLD;
 
 	cdns_i2c_writereg(ctrl_reg, CDNS_I2C_CR_OFFSET);
 
-- 
2.17.1