mfd: rtsx_usb: Defer autosuspend while card exists

A card insertion happens after the lastest polling before reader is
suspended may never have a chance to be detected. Under current 1-HZ
polling interval setting in mmc_core, the worst case of such
undetectablility is about 1 second.

To further reduce the undetectability, detect card slot again in suspend
method and defer the autosuspend if the slot is loaded. The default 2
second autosuspend delay of USB subsystem should let the next polling
detects the card.

Signed-off-by: Roger Tseng <rogerable@realtek.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

1 files changed, 18 insertions, 0 deletions

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;
 }