• Tony Lindgren's avatar
    usb: musb: Fix hardirq-safe hardirq-unsafe lock order error · d8e5f0ec
    Tony Lindgren authored
    If we configure musb with 2430 glue as a peripheral, and then rmmod
    omap2430 module, we'll get the following error:
    
    [ INFO: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected ]
    ...
    rmmod/413 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
     (&phy->mutex){+.+.+.}, at: [<c04b9fd0>] phy_power_off+0x1c/0xb8
    [  204.678710]
                   and this task is already holding:
     (&(&musb->lock)->rlock){-.-...}, at: [<bf3a482c>]
     musb_gadget_stop+0x24/0xec [musb_hdrc]
    which would create a new lock dependency:
     (&(&musb->lock)->rlock){-.-...} -> (&phy->mutex){+.+.+.}
    ...
    
    This is because some glue layers expect musb_platform_enable/disable
    to be called with spinlock held, and 2430 glue layer has USB PHY on
    the I2C bus using a mutex.
    
    We could fix the glue layers to take the spinlock, but we still have
    a problem of musb_plaform_enable/disable being called in an unbalanced
    manner. So that would still lead into USB PHY enable/disable related
    problems for omap2430 glue layer.
    
    While it makes sense to only enable USB PHY when needed from PM point
    of view, in this case we just can't do it yet without breaking things.
    So let's just revert phy_enable/disable related changes instead and
    reconsider this after we have fixed musb_platform_enable/disable to
    be balanced.
    
    Fixes: a83e17d0 ("usb: musb: Improve PM runtime and phy handling for 2430 glue layer")
    Reviewed-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
    Signed-off-by: default avatarTony Lindgren <tony@atomide.com>
    Signed-off-by: default avatarBin Liu <b-liu@ti.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    d8e5f0ec
omap2430.c 15.7 KB