[PATCH v2] i2c: rcar: slave: only send STOP event when we have been addressed

[PATCH v2] i2c: rcar: slave: only send STOP event when we have been addressed

[Wolfram Sang]

When the SSR interrupt is activated, it will detect every STOP condition
on the bus, not only the ones after we have been addressed. So, enable
this interrupt only after we have been addressed, and disable it
otherwise.

Fixes: de20d1857dd6 ("i2c: rcar: add slave support")
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---

Change since v1: It is probably cleaner to clear the SSR flag before we
enable the SSR interrupt.

 drivers/i2c/busses/i2c-rcar.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index a45c4bf1ec01..51a3909f8688 100644
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -572,6 +572,9 @@ static bool rcar_i2c_slave_irq(struct rcar_i2c_priv *priv)
 
 	/* address detected */
 	if (ssr_filtered & SAR) {
+		/* Clear SSR, too, because of old STOPs to other clients than us */
+		rcar_i2c_write(priv, ICSSR, ~(SAR | SSR) & 0xff);
+
 		/* read or write request */
 		if (ssr_raw & STM) {
 			i2c_slave_event(priv->slave, I2C_SLAVE_READ_REQUESTED, &value);
@@ -582,14 +585,12 @@ static bool rcar_i2c_slave_irq(struct rcar_i2c_priv *priv)
 			rcar_i2c_read(priv, ICRXTX);	/* dummy read */
 			rcar_i2c_write(priv, ICSIER, SDR | SSR | SAR);
 		}
-
-		rcar_i2c_write(priv, ICSSR, ~SAR & 0xff);
 	}
 
 	/* master sent stop */
 	if (ssr_filtered & SSR) {
 		i2c_slave_event(priv->slave, I2C_SLAVE_STOP, &value);
-		rcar_i2c_write(priv, ICSIER, SAR | SSR);
+		rcar_i2c_write(priv, ICSIER, SAR);
 		rcar_i2c_write(priv, ICSSR, ~SSR & 0xff);
 	}
 
@@ -853,7 +854,7 @@ static int rcar_reg_slave(struct i2c_client *slave)
 	priv->slave = slave;
 	rcar_i2c_write(priv, ICSAR, slave->addr);
 	rcar_i2c_write(priv, ICSSR, 0);
-	rcar_i2c_write(priv, ICSIER, SAR | SSR);
+	rcar_i2c_write(priv, ICSIER, SAR);
 	rcar_i2c_write(priv, ICSCR, SIE | SDBS);
 
 	return 0;
-- 
2.20.1

Re: [PATCH v2] i2c: rcar: slave: only send STOP event when we have been addressed

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 763 bytes --]

On Mon, Jun 29, 2020 at 06:15:06PM +0200, Wolfram Sang wrote:
> When the SSR interrupt is activated, it will detect every STOP condition
> on the bus, not only the ones after we have been addressed. So, enable
> this interrupt only after we have been addressed, and disable it
> otherwise.
> 
> Fixes: de20d1857dd6 ("i2c: rcar: add slave support")
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> ---
> 
> Change since v1: It is probably cleaner to clear the SSR flag before we
> enable the SSR interrupt.

I am going to apply v1 of this patch. The above is not cleaner. It is
cleaner to clear SAR only when we are done with everything to make sure
SCL is stretched long enough. Clearing SSR a tad later is still good
enough.


[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]