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usb: musb: call pm_runtime_{get,put}_sync before reading vbus registers

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 <>
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MerlijnWajer committed Feb 24, 2018
1 parent 871229e commit b090e83acf4f71fd354c3fe82aeff9b7ae1dd3c2
Showing with 2 additions and 0 deletions.
  1. +2 −0 drivers/usb/musb/musb_core.c
@@ -1756,6 +1756,7 @@ musb_vbus_show(struct device *dev, struct device_attribute *attr, char *buf)
int vbus;
u8 devctl;

spin_lock_irqsave(&musb->lock, flags);
val = musb->a_wait_bcon;
vbus = musb_platform_get_vbus_status(musb);
@@ -1769,6 +1770,7 @@ musb_vbus_show(struct device *dev, struct device_attribute *attr, char *buf)
vbus = 0;
spin_unlock_irqrestore(&musb->lock, flags);

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

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