The timeout for transfers was only set to 2ms. Because of this relatively
low limit, 12-byte read operations to the frontend MCU of a RTL8239 POE PSE
chip cluster was consistently resulting in a timeout.

The original OpenWrt downstream driver [1] was not using any timeout limit
at all. This is also possible by setting the timeout_us parameter of
regmap_read_poll_timeout() to 0. But since the driver currently is
implements the ETIMEDOUT error, it is more sensible to increase the timeout
in such a way that the communication with the (quite common) Realtek
I2C-connected POE management solution is possible.

[1] https://git.openwrt.org/?p=openwrt/openwrt.git;a=blob;f=target/linux/realtek/files-6.12/drivers/i2c/busses/i2c-rtl9300.c;h=c4d973195ef39dc56d6207e665d279745525fcac#l202

Cc: <stable@vger.kernel.org>
Fixes: c366be720235 ("i2c: Add driver for the RTL9300 I2C controller")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 drivers/i2c/busses/i2c-rtl9300.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-rtl9300.c b/drivers/i2c/busses/i2c-rtl9300.c
index 1b3cbe3ea84a4fa480c5c00438eecc551d047348..a10e5e6e00075fabb8906d56f09f5b9141fbc06e 100644
--- a/drivers/i2c/busses/i2c-rtl9300.c
+++ b/drivers/i2c/busses/i2c-rtl9300.c
@@ -178,7 +178,7 @@ static int rtl9300_i2c_execute_xfer(struct rtl9300_i2c *i2c, char read_write,
 		return ret;
 
 	ret = regmap_read_poll_timeout(i2c->regmap, i2c->reg_base + RTL9300_I2C_MST_CTRL1,
-				       val, !(val & RTL9300_I2C_MST_CTRL1_I2C_TRIG), 100, 2000);
+				       val, !(val & RTL9300_I2C_MST_CTRL1_I2C_TRIG), 100, 100000);
 	if (ret)
 		return ret;
 

-- 
2.47.2