[PATCH 4.19 38/86] i2c: rcar: always clear ICSAR to avoid side effects

Greg Kroah-Hartman
2020-07-27T14:11:53Z

From: Wolfram Sang <wsa+renesas@sang-engineering.com>

[ Upstream commit eb01597158ffb1853a7a7fc2c57d4c844640f75e ]

On R-Car Gen2, we get a timeout when reading from the address set in
ICSAR, even though the slave interface is disabled. Clearing it fixes
this situation. Note that Gen3 is not affected.

To reproduce: bind and undbind an I2C slave on some bus, run
'i2cdetect' on that bus.

Fixes: de20d1857dd6 ("i2c: rcar: add slave support")
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/i2c/busses/i2c-rcar.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index 2c29f901d3090..6e49e438ef5a5 100644
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -863,6 +863,7 @@ static int rcar_unreg_slave(struct i2c_client *slave)
/* disable irqs and ensure none is running before clearing ptr */
rcar_i2c_write(priv, ICSIER, 0);
rcar_i2c_write(priv, ICSCR, 0);
+ rcar_i2c_write(priv, ICSAR, 0); /* Gen2: must be 0 if not using slave */

synchronize_irq(priv->irq);
priv->slave = NULL;
@@ -966,6 +967,8 @@ static int rcar_i2c_probe(struct platform_device *pdev)
if (ret < 0)
goto out_pm_put;

+ rcar_i2c_write(priv, ICSAR, 0); /* Gen2: must be 0 if not using slave */
+
if (priv->devtype == I2C_RCAR_GEN3) {
priv->rstc = devm_reset_control_get_exclusive(&pdev->dev, NULL);
if (!IS_ERR(priv->rstc)) {
--
2.25.1