linux-kernel - [PATCH v2] usb: musb: fix pm

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Date:	Mon, 19 Dec 2011 22:01:54 +0200
From:	Felipe Contreras <felipe.contreras@...ia.com>
To:	linux-usb@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org,
	linux-omap <linux-omap@...r.kernel.org>,
	Felipe Balbi <balbi@...com>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Jarkko Nikula <jarkko.nikula@...mer.com>,
	Felipe Contreras <felipe.contreras@...il.com>,
	stable@...r.kernel.org, Hema HK <hemahk@...com>
Subject: [PATCH v2] usb: musb: fix pm_runtime mismatch

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

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: stable@...r.kernel.org
Cc: Hema HK <hemahk@...com>
Signed-off-by: Felipe Contreras <felipe.contreras@...il.com>
---
 drivers/usb/musb/musb_core.c |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
index b63ab15..920f04e 100644
--- a/drivers/usb/musb/musb_core.c
+++ b/drivers/usb/musb/musb_core.c
@@ -2012,8 +2012,6 @@ musb_init_controller(struct device *dev, int nIrq, void __iomem *ctrl)
 	if (status < 0)
 		goto fail3;
 
-	pm_runtime_put(musb->controller);
-
 	status = musb_init_debugfs(musb);
 	if (status < 0)
 		goto fail4;
-- 
1.7.8

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