phy: sun4i-usb: Use spinlock to guard phyctl register access
commit 919ab252 upstream. The musb driver calls into this phy driver to disable/enable squelch detection. This function was introduced in 24fe86a6 ("phy: sun4i-usb: Add a sunxi specific function for setting squelch-detect"). This function in turn calls sun4i_usb_phy_write, which uses a mutex to guard the common access register. Unfortunately musb does this in atomic context, which results in the following warning with lock debugging enabled: BUG: sleeping function called from invalid context at kernel/locking/mutex.c:97 in_atomic(): 1, irqs_disabled(): 128, pid: 96, name: kworker/0:2 CPU: 0 PID: 96 Comm: kworker/0:2 Not tainted 4.8.0-rc4-00181-gd502f8ad1c3e #13 Hardware name: Allwinner sun8i Family Workqueue: events musb_deassert_reset [<c010bc01>] (unwind_backtrace) from [<c0109237>] (show_stack+0xb/0xc) [<c0109237>] (show_stack) from [<c02a669b>] (dump_stack+0x67/0x74) [<c02a669b>] (dump_stack) from [<c05d68c9>] (mutex_lock+0x15/0x2c) [<c05d68c9>] (mutex_lock) from [<c02c3589>] (sun4i_usb_phy_write+0x39/0xec) [<c02c3589>] (sun4i_usb_phy_write) from [<c03e6327>] (musb_port_reset+0xfb/0x184) [<c03e6327>] (musb_port_reset) from [<c03e4917>] (musb_deassert_reset+0x1f/0x2c) [<c03e4917>] (musb_deassert_reset) from [<c012ecb5>] (process_one_work+0x129/0x2b8) [<c012ecb5>] (process_one_work) from [<c012f5e3>] (worker_thread+0xf3/0x424) [<c012f5e3>] (worker_thread) from [<c0132dbd>] (kthread+0xa1/0xb8) [<c0132dbd>] (kthread) from [<c0105f31>] (ret_from_fork+0x11/0x20) Since the register access is mmio, we can use a spinlock to guard this specific access, rather than the mutex that guards the entire phy. Fixes: ba4bdc9e ("PHY: sunxi: Add driver for sunxi usb phy") Cc: Hans de Goede <hdegoede@redhat.com> Signed-off-by:Chen-Yu Tsai <wens@csie.org> Reviewed-by:
Hans de Goede <hdegoede@redhat.com> Signed-off-by:
Kishon Vijay Abraham I <kishon@ti.com> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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