linux-kernel - [PATCH 2/2] mfd: rtsx_usb: Defer autosuspend while card exists

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Message-ID: <1421306085-32254-3-git-send-email-rogerable@realtek.com>
Date:	Thu, 15 Jan 2015 15:14:45 +0800
From:	Roger Tseng <rogerable@...ltek.com>
To:	Samuel Ortiz <sameo@...ux.intel.com>,
	Lee Jones <lee.jones@...aro.org>
CC:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	<linux-kernel@...r.kernel.org>,
	<driverdev-devel@...uxdriverproject.org>,
	<wei_wang@...lsil.com.cn>, <micky_ching@...lsil.com.cn>,
	Roger Tseng <rogerable@...ltek.com>
Subject: [PATCH 2/2] 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@...ltek.com>
---
 drivers/mfd/rtsx_usb.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/mfd/rtsx_usb.c b/drivers/mfd/rtsx_usb.c
index 076694126e5d..63883fd025c0 100644
--- a/drivers/mfd/rtsx_usb.c
+++ b/drivers/mfd/rtsx_usb.c
@@ -687,6 +687,20 @@ static int rtsx_usb_suspend(struct usb_interface *intf, pm_message_t message)
 	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;
 }
 
-- 
2.1.3

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