[PATCH 2/3] drivers/card_reader/rtsx_usb: Add interrupt based detection

[Sean Rhodes <sean@starlabs.systems>]

This commit introduces interrupt-based card detection, identical to
the `rts5139` driver in staging.

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

Cc: stable@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sean Rhodes <sean@starlabs.systems>
---
 drivers/misc/cardreader/rtsx_usb.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/misc/cardreader/rtsx_usb.c b/drivers/misc/cardreader/rtsx_usb.c
index f150d8769f19..285a748748d7 100644
--- a/drivers/misc/cardreader/rtsx_usb.c
+++ b/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;
-- 
2.43.0