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Subject[PATCH 4.4 126/268] usb: musb: call pm_runtime_{get,put}_sync before reading vbus registers
4.4-stable review patch.  If anyone has any objections, please let me know.


From: Merlijn Wajer <>

[ Upstream commit df6b074dbe248d8c43a82131e8fd429e401841a5 ]

Without pm_runtime_{get,put}_sync calls in place, reading
vbus status via /sys causes the following error:

Unhandled fault: external abort on non-linefetch (0x1028) at 0xfa0ab060
pgd = b333e822
[fa0ab060] *pgd=48011452(bad)

[<c05261b0>] (musb_default_readb) from [<c0525bd0>] (musb_vbus_show+0x58/0xe4)
[<c0525bd0>] (musb_vbus_show) from [<c04c0148>] (dev_attr_show+0x20/0x44)
[<c04c0148>] (dev_attr_show) from [<c0259f74>] (sysfs_kf_seq_show+0x80/0xdc)
[<c0259f74>] (sysfs_kf_seq_show) from [<c0210bac>] (seq_read+0x250/0x448)
[<c0210bac>] (seq_read) from [<c01edb40>] (__vfs_read+0x1c/0x118)
[<c01edb40>] (__vfs_read) from [<c01edccc>] (vfs_read+0x90/0x144)
[<c01edccc>] (vfs_read) from [<c01ee1d0>] (SyS_read+0x3c/0x74)
[<c01ee1d0>] (SyS_read) from [<c0106fe0>] (ret_fast_syscall+0x0/0x54)

Solution was suggested by Tony Lindgren <>.

Signed-off-by: Merlijn Wajer <>
Acked-by: Tony Lindgren <>
Signed-off-by: Bin Liu <>
Signed-off-by: Sasha Levin <>
Signed-off-by: Greg Kroah-Hartman <>
drivers/usb/musb/musb_core.c | 2 ++
1 file changed, 2 insertions(+)

--- a/drivers/usb/musb/musb_core.c
+++ b/drivers/usb/musb/musb_core.c
@@ -1775,6 +1775,7 @@ musb_vbus_show(struct device *dev, struc
int vbus;
u8 devctl;

+ pm_runtime_get_sync(dev);
spin_lock_irqsave(&musb->lock, flags);
val = musb->a_wait_bcon;
vbus = musb_platform_get_vbus_status(musb);
@@ -1788,6 +1789,7 @@ musb_vbus_show(struct device *dev, struc
vbus = 0;
spin_unlock_irqrestore(&musb->lock, flags);
+ pm_runtime_put_sync(dev);

return sprintf(buf, "Vbus %s, timeout %lu msec\n",
vbus ? "on" : "off", val);

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