Commit 9e565114 authored Mar 05, 2018 by Merlijn Wajer Committed by Greg Kroah-Hartman Apr 29, 2018

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



commit df6b074dbe248d8c43a82131e8fd429e401841a5 upstream.

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 <tony@atomide.com>.

Signed-off-by: Merlijn Wajer <merlijn@wizzup.org>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent c274101c

drivers/usb/musb/musb_core.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -1774,6 +1774,7 @@ musb_vbus_show(struct device dev, struct device_attribute attr, char *buf)
		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);
		@@ -1787,6 +1788,7 @@ musb_vbus_show(struct device dev, struct device_attribute attr, char *buf)
		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);