linux-kernel - [26/42] usb: musb: fix pm

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Date:	Tue, 10 Jan 2012 13:48:36 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Hema HK <hemahk@...com>,
	Felipe Contreras <felipe.contreras@...il.com>,
	Felipe Balbi <balbi@...com>
Subject: [26/42] usb: musb: fix pm_runtime mismatch

3.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Felipe Contreras <felipe.contreras@...il.com>

commit 772aed45b604c5ff171f0f12c12392d868333f79 upstream.

In musb_init_controller() there's a pm_runtime_put(), but there's no
pm_runtime_get(), which creates a mismatch that causes the driver to
sleep when it shouldn't.

This was introduced in 7acc619[1], but it wasn't triggered in my setup
until 18a2689[2] was merged to Linus' branch at point df0914[3]. IOW;
when PM is working as it was supposed to.

However, it seems most of the time this is used in a way that keeps the
counter above 0, so nobody noticed. Also, it seems to depend on the
configuration used in versions before 3.1, but not later (or in it).

I found the problem by loading isp1704_charger before any usb gadgets:
http://article.gmane.org/gmane.linux.kernel/1226122

All versions after 2.6.39 are affected.

[1] usb: musb: Idle path retention and offmode support for OMAP3
[2] OMAP2+: musb: hwmod adaptation for musb registration
[3] Merge branch 'omap-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap-2.6

Cc: Hema HK <hemahk@...com>
Signed-off-by: Felipe Contreras <felipe.contreras@...il.com>
Signed-off-by: Felipe Balbi <balbi@...com>

---
 drivers/usb/musb/musb_core.c |    2 --
 1 file changed, 2 deletions(-)

--- a/drivers/usb/musb/musb_core.c
+++ b/drivers/usb/musb/musb_core.c
@@ -2013,8 +2013,6 @@ musb_init_controller(struct device *dev,
 	if (status < 0)
 		goto fail3;
 
-	pm_runtime_put(musb->controller);
-
 	status = musb_init_debugfs(musb);
 	if (status < 0)
 		goto fail4;


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