[PATCH 1/2] mfd: rtsx_usb: Fix runtime PM deadlock

[Roger Tseng]

On Tue, 2015-01-20 at 16:07 +0000, Lee Jones wrote:
> On Tue, 20 Jan 2015, Roger Tseng wrote:
> 
> > On Mon, 2015-01-19 at 09:45 +0000, Lee Jones wrote:
> > > On Thu, 15 Jan 2015, Roger Tseng wrote:
> > > 
> > > > sd_set_power_mode() in derived module drivers/mmc/host/rtsx_usb_sdmmc.c
> > > > acquires dev_mutex and then calls pm_runtime_get_sync() to make sure the
> > > > device is awake while initializing a newly inserted card. Once it is
> > > > called during suspending state and explicitly before rtsx_usb_suspend()
> > > > acquires the same dev_mutex, both routine deadlock and further hang the
> > > > driver because pm_runtime_get_sync() waits the pending PM operations.
> > > > 
> > > > Fix this by using an empty suspend method. mmc_core always turns the
> > > > LED off after a request is done and thus it is ok to remove the only
> > > > rtsx_usb_turn_off_led() here.
> > > > 
> > > > Cc: <stable at vger.kernel.org> # v3.16+
> > > > Fixes: 730876be2566 ("mfd: Add realtek USB card reader driver")
> > > > Signed-off-by: Roger Tseng <rogerable at realtek.com>
> > > > ---
> > > >  drivers/mfd/rtsx_usb.c | 9 ---------
> > > >  1 file changed, 9 deletions(-)
> > > 
> > > Applied, thanks.
> > > 
> > I'm sorry but build bot from Intel just reported me that I forgot to
> > delete an unused variable "ucr" between two commits. My bad.
> > 
> > Do I have a chance to send v2?
> 
> You're lucky I'm in a good mood. ;)
> 
> I fixed it already.
> 
That's great, thanks! And thus patch 2/2 also needs to be changed
accordingly.

By the way, the build bot reported again about an undefined variable
build error in 2/2(I'm sorry for this again). I put the overall updated
content of 2/2 here for you if you're going to fix it, or I can also
re-send it individually.

diff --git a/drivers/mfd/rtsx_usb.c b/drivers/mfd/rtsx_usb.c
index 210d1f85679e..ede50244f265 100644
--- a/drivers/mfd/rtsx_usb.c
+++ b/drivers/mfd/rtsx_usb.c
@@ -681,9 +681,27 @@ static void rtsx_usb_disconnect(struct
usb_interface *intf)
 #ifdef CONFIG_PM
 static int rtsx_usb_suspend(struct usb_interface *intf, pm_message_t
message)
 {
+	struct rtsx_ucr *ucr =
+		(struct rtsx_ucr *)usb_get_intfdata(intf);
+	u16 val = 0;
+
 	dev_dbg(&intf->dev, "%s called with pm message 0x%04x\n",
 			__func__, message.event);
 
+	if (PMSG_IS_AUTO(message)) {
+		if (mutex_trylock(&ucr->dev_mutex)) {
+			rtsx_usb_get_card_status(ucr, &val);
+			mutex_unlock(&ucr->dev_mutex);
+
+			/* Defer the autosuspend if card exists */
+			if (val & (SD_CD | MS_CD))
+				return -EAGAIN;
+		} else {
+			/* There is an ongoing operation*/
+			return -EAGAIN;
+		}
+	}
+
 	return 0;
 }



> > > > diff --git a/drivers/mfd/rtsx_usb.c b/drivers/mfd/rtsx_usb.c
> > > > index dbdd0faeb6ce..076694126e5d 100644
> > > > --- a/drivers/mfd/rtsx_usb.c
> > > > +++ b/drivers/mfd/rtsx_usb.c
> > > > @@ -687,15 +687,6 @@ static int rtsx_usb_suspend(struct usb_interface *intf, pm_message_t message)
> > > >  	dev_dbg(&intf->dev, "%s called with pm message 0x%04x\n",
> > > >  			__func__, message.event);
> > > >  
> > > > -	/*
> > > > -	 * Call to make sure LED is off during suspend to save more power.
> > > > -	 * It is NOT a permanent state and could be turned on anytime later.
> > > > -	 * Thus no need to call turn_on when resunming.
> > > > -	 */
> > > > -	mutex_lock(&ucr->dev_mutex);
> > > > -	rtsx_usb_turn_off_led(ucr);
> > > > -	mutex_unlock(&ucr->dev_mutex);
> > > > -
> > > >  	return 0;
> > > >  }
> > > >  
> > > 
> > 
> 

-- 
Best regards,
Roger Tseng