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 332d32c53c41..73324f047932 100644 --- a/drivers/i2c/busses/i2c-mv64xxx.c +++ b/drivers/i2c/busses/i2c-mv64xxx.c @@ -219,6 +219,10 @@ 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; }