mmc: rtsx_usb_sdmmc: Handle runtime PM while changing the led

BugLink: http://bugs.launchpad.net/bugs/1637510

commit 4f48aa7a upstream.

Accesses of the rtsx sdmmc's parent device, which is the rtsx usb device,
must be done when it's runtime resumed. Currently this isn't case when
changing the led, so let's fix this by adding a pm_runtime_get_sync() and
a pm_runtime_put() around those operations.
Reported-by: Ritesh Raj Sarraf <rrs@researchut.com>
Tested-by: Ritesh Raj Sarraf <rrs@researchut.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

drivers/mmc/host/rtsx_usb_sdmmc.c

@@ -1309,6 +1309,7 @@ static void rtsx_usb_update_led(struct work_struct *work)
 		container_of(work, struct rtsx_usb_sdmmc, led_work);
 	struct rtsx_ucr *ucr = host->ucr;
 
+	pm_runtime_get_sync(sdmmc_dev(host));
 	mutex_lock(&ucr->dev_mutex);
 
 	if (host->led.brightness == LED_OFF)
@@ -1317,6 +1318,7 @@ static void rtsx_usb_update_led(struct work_struct *work)
 		rtsx_usb_turn_on_led(ucr);
 
 	mutex_unlock(&ucr->dev_mutex);
+	pm_runtime_put(sdmmc_dev(host));
 }
 #endif