Patch "i2c: rcar: bring hardware to known state when probing" has been added to the 6.9-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    i2c: rcar: bring hardware to known state when probing

to the 6.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     i2c-rcar-bring-hardware-to-known-state-when-probing.patch
and it can be found in the queue-6.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit a86d50f061ff40c902a50ab8a38421827910acf7
Author: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
Date:   Sun Jul 7 10:28:46 2024 +0200

    i2c: rcar: bring hardware to known state when probing
    
    [ Upstream commit 4e36c0f20cb1c74c7bd7ea31ba432c1c4a989031 ]
    
    When probing, the hardware is not brought into a known state. This may
    be a problem when a hypervisor restarts Linux without resetting the
    hardware, leaving an old state running. Make sure the hardware gets
    initialized, especially interrupts should be cleared and disabled.
    
    Reported-by: Dirk Behme <dirk.behme@xxxxxxxxxxxx>
    Reported-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
    Closes: https://lore.kernel.org/r/20240702045535.2000393-1-dirk.behme@xxxxxxxxxxxx
    Fixes: 6ccbe607132b ("i2c: add Renesas R-Car I2C driver")
    Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Andi Shyti <andi.shyti@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index 828aa2ea0fe4c..ec73463ea9b5e 100644
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -257,6 +257,14 @@ static void rcar_i2c_init(struct rcar_i2c_priv *priv)
 	}
 }
 
+static void rcar_i2c_reset_slave(struct rcar_i2c_priv *priv)
+{
+	rcar_i2c_write(priv, ICSIER, 0);
+	rcar_i2c_write(priv, ICSSR, 0);
+	rcar_i2c_write(priv, ICSCR, SDBS);
+	rcar_i2c_write(priv, ICSAR, 0); /* Gen2: must be 0 if not using slave */
+}
+
 static int rcar_i2c_bus_barrier(struct rcar_i2c_priv *priv)
 {
 	int ret;
@@ -1033,11 +1041,8 @@ static int rcar_unreg_slave(struct i2c_client *slave)
 
 	/* ensure no irq is running before clearing ptr */
 	disable_irq(priv->irq);
-	rcar_i2c_write(priv, ICSIER, 0);
-	rcar_i2c_write(priv, ICSSR, 0);
+	rcar_i2c_reset_slave(priv);
 	enable_irq(priv->irq);
-	rcar_i2c_write(priv, ICSCR, SDBS);
-	rcar_i2c_write(priv, ICSAR, 0); /* Gen2: must be 0 if not using slave */
 
 	priv->slave = NULL;
 
@@ -1152,7 +1157,9 @@ static int rcar_i2c_probe(struct platform_device *pdev)
 		goto out_pm_disable;
 	}
 
-	rcar_i2c_write(priv, ICSAR, 0); /* Gen2: must be 0 if not using slave */
+	/* Bring hardware to known state */
+	rcar_i2c_init(priv);
+	rcar_i2c_reset_slave(priv);
 
 	if (priv->devtype < I2C_RCAR_GEN3) {
 		irqflags |= IRQF_NO_THREAD;