From 39930213e7779b9c4257499972b8afb8858f1a2d Mon Sep 17 00:00:00 2001 From: Marek Behún Date: Thu, 8 Apr 2021 04:00:00 +0200 Subject: i2c: mv64xxx: Fix random system lock caused by runtime PM 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 Acked-by: Gregory CLEMENT Reviewed-by: Samuel Holland Signed-off-by: Wolfram Sang --- drivers/i2c/busses/i2c-mv64xxx.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'drivers') diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c index c590d36b5fd1..5c8e94b6cdb5 100644 --- a/drivers/i2c/busses/i2c-mv64xxx.c +++ b/drivers/i2c/busses/i2c-mv64xxx.c @@ -221,6 +221,10 @@ 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; } -- cgit v1.2.3