• Marek Behún's avatar
    i2c: mv64xxx: Fix random system lock caused by runtime PM · 39930213
    Marek Behún authored
    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>
    39930213
i2c-mv64xxx.c 29.3 KB