drivers/card_reader/rtsx_usb: Restore interrupt based detection

This commit reintroduces interrupt-based card detection previously
used in the rts5139 driver. This functionality was removed in commit
00d8521dcd ("staging: remove rts5139 driver code").

Reintroducing this mechanism fixes presence detection for certain card
readers, which with the current driver, will taken approximately 20
seconds to enter S3 as `mmc_rescan` has to be frozen.

Fixes: 00d8521dcd ("staging: remove rts5139 driver code")
Cc: [email protected]
Cc: Arnd Bergmann <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Sean Rhodes <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

drivers/misc/cardreader/rtsx_usb.c

@@ -286,6 +286,7 @@ static int rtsx_usb_get_status_with_bulk(struct rtsx_ucr *ucr, u16 *status)
 int rtsx_usb_get_card_status(struct rtsx_ucr *ucr, u16 *status)
 {
 	int ret;
+	u8 interrupt_val = 0;
 	u16 *buf;
 
 	if (!status)
@@ -308,6 +309,20 @@ int rtsx_usb_get_card_status(struct rtsx_ucr *ucr, u16 *status)
 		ret = rtsx_usb_get_status_with_bulk(ucr, status);
 	}
 
+	rtsx_usb_read_register(ucr, CARD_INT_PEND, &interrupt_val);
+	/* Cross check presence with interrupts */
+	if (*status & XD_CD)
+		if (!(interrupt_val & XD_INT))
+			*status &= ~XD_CD;
+
+	if (*status & SD_CD)
+		if (!(interrupt_val & SD_INT))
+			*status &= ~SD_CD;
+
+	if (*status & MS_CD)
+		if (!(interrupt_val & MS_INT))
+			*status &= ~MS_CD;
+
 	/* usb_control_msg may return positive when success */
 	if (ret < 0)
 		return ret;