Commit 39930213 authored by Marek Behún's avatar Marek Behún Committed by Wolfram Sang
Browse files

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 e5c02cf5 ("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: default avatarMarek Behún <kabel@kernel.org>
Acked-by: default avatarGregory CLEMENT <gregory.clement@bootlin.com>
Reviewed-by: default avatarSamuel Holland <samuel@sholland.org>
Signed-off-by: default avatarWolfram Sang <wsa@kernel.org>
parent d434405a

drivers/i2c/busses/i2c-mv64xxx.c

+4 −0
Original line number Diff line number Diff line
@@ -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;

}