* [PATCH AUTOSEL 4.9 6/8] i2c: mv64xxx: Fix random system lock caused by runtime PM
[not found] <20210419204554.7071-1-sashal@kernel.org>
@ 2021-04-19 20:45 ` Sasha Levin
0 siblings, 0 replies; only message in thread
From: Sasha Levin @ 2021-04-19 20:45 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Marek Behún, Gregory CLEMENT, Samuel Holland, Wolfram Sang,
Sasha Levin, linux-i2c
From: Marek Behún <kabel@kernel.org>
[ Upstream commit 39930213e7779b9c4257499972b8afb8858f1a2d ]
I noticed a weird bug with this driver on Marvell CN9130 Customer
Reference Board.
Sometime after boot, the system locks with the following message:
[104.071363] i2c i2c-0: mv64xxx: I2C bus locked, block: 1, time_left: 0
The system does not respond afterwards, only warns about RCU stalls.
This first appeared with commit e5c02cf54154 ("i2c: mv64xxx: Add runtime
PM support").
With further experimentation I discovered that adding a delay into
mv64xxx_i2c_hw_init() fixes this issue. This function is called before
every xfer, due to how runtime PM works in this driver. It seems that in
order to work correctly, a delay is needed after the bus is reset in
this function.
Since there already is a known erratum with this controller needing a
delay, I assume that this is just another place this needs to be
applied. Therefore I apply the delay only if errata_delay is true.
Signed-off-by: Marek Behún <kabel@kernel.org>
Acked-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Reviewed-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/i2c/busses/i2c-mv64xxx.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
index 5c9dea7a40bc..b10e89b4f8e9 100644
--- a/drivers/i2c/busses/i2c-mv64xxx.c
+++ b/drivers/i2c/busses/i2c-mv64xxx.c
@@ -217,6 +217,10 @@ mv64xxx_i2c_hw_init(struct mv64xxx_i2c_data *drv_data)
writel(0, drv_data->reg_base + drv_data->reg_offsets.ext_addr);
writel(MV64XXX_I2C_REG_CONTROL_TWSIEN | MV64XXX_I2C_REG_CONTROL_STOP,
drv_data->reg_base + drv_data->reg_offsets.control);
+
+ if (drv_data->errata_delay)
+ udelay(5);
+
drv_data->state = MV64XXX_I2C_STATE_IDLE;
}
--
2.30.2
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