linux-kernel - [PATCH] misc: rtsx: usb: Ensure mmc child device is active when card is present

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Message-ID: <20250711140143.2105224-1-ricky_wu@realtek.com>
Date: Fri, 11 Jul 2025 22:01:43 +0800
From: Ricky Wu <ricky_wu@...ltek.com>
To: <linux-kernel@...r.kernel.org>, <arnd@...db.de>,
        <gregkh@...uxfoundation.org>, <mingo@...nel.org>,
        <ricky_wu@...ltek.com>, <ulf.hansson@...aro.org>,
        <kai.heng.feng@...onical.com>
CC: <stable@...r.kernel.org>
Subject: [PATCH] misc: rtsx: usb: Ensure mmc child device is active when card is present

When a card is present in the reader, the driver currently defers
autosuspend by returning -EAGAIN during the suspend callback to
trigger USB remote wakeup signaling. However, this does not guarantee
that the mmc child device has been resumed, which may cause issues if
it remains suspended while the card is accessible.
This patch ensures that all child devices, including the mmc host
controller, are explicitly resumed before returning -EAGAIN. This
fixes a corner case introduced by earlier remote wakeup handling,
improving reliability of runtime PM when a card is inserted.

Fixes: 883a87ddf2f1 ("misc: rtsx_usb: Use USB remote wakeup signaling for card insertion detection")
Cc: stable@...r.kernel.org
Signed-off-by: Ricky Wu <ricky_wu@...ltek.com>
---
 drivers/misc/cardreader/rtsx_usb.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/misc/cardreader/rtsx_usb.c b/drivers/misc/cardreader/rtsx_usb.c
index 148107a4547c..d007a4455ce5 100644
--- a/drivers/misc/cardreader/rtsx_usb.c
+++ b/drivers/misc/cardreader/rtsx_usb.c
@@ -698,6 +698,12 @@ static void rtsx_usb_disconnect(struct usb_interface *intf)
 }
 
 #ifdef CONFIG_PM
+static int rtsx_usb_resume_child(struct device *dev, void *data)
+{
+	pm_request_resume(dev);
+	return 0;
+}
+
 static int rtsx_usb_suspend(struct usb_interface *intf, pm_message_t message)
 {
 	struct rtsx_ucr *ucr =
@@ -713,8 +719,10 @@ static int rtsx_usb_suspend(struct usb_interface *intf, pm_message_t message)
 			mutex_unlock(&ucr->dev_mutex);
 
 			/* Defer the autosuspend if card exists */
-			if (val & (SD_CD | MS_CD))
+			if (val & (SD_CD | MS_CD)) {
+				device_for_each_child(&intf->dev, NULL, rtsx_usb_resume_child);
 				return -EAGAIN;
+			}
 		} else {
 			/* There is an ongoing operation*/
 			return -EAGAIN;
@@ -724,12 +732,6 @@ static int rtsx_usb_suspend(struct usb_interface *intf, pm_message_t message)
 	return 0;
 }
 
-static int rtsx_usb_resume_child(struct device *dev, void *data)
-{
-	pm_request_resume(dev);
-	return 0;
-}
-
 static int rtsx_usb_resume(struct usb_interface *intf)
 {
 	device_for_each_child(&intf->dev, NULL, rtsx_usb_resume_child);
-- 
2.25.1