linux-kernel - [PATCH v2] mmc: dw_mmc: insmod followed by rmmod will hung for eMMC

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Message-ID: <705D14B1C7978B40A723277C067CEDE245184BC7@IN01WEMBXB.internal.synopsys.com>
Date:	Thu, 28 May 2015 12:21:06 +0000
From:	Prabu Thangamuthu <Prabu.T@...opsys.com>
To:	Seungwon Jeon <tgih.jun@...sung.com>,
	Jaehoon Chung <jh80.chung@...sung.com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:	Manjunath M Bettegowda <Manjunath.MB@...opsys.com>,
	"prabu.t@...opsys.com" <prabu.t@...opsys.com>
Subject: [PATCH v2] mmc: dw_mmc: insmod followed by rmmod will hung for eMMC

Remove module of dw_mmc driver will hung for eMMC devices if we follow the
steps which are listed below,
	insmod dw_mmc.ko
	insmod dw_mmc-pci.ko
	rmmod dw_mmc-pci.ko

The root cause for this issue is, dw_mci_remove() will disable all the
interrupts by programming 0x0 to INTMASK register then it will call
dw_mci_cleanup_slot(). But dw_mci_cleanup_slot() is issuing CMD6 to
disable the eMMC boot partition and it is waiting for Command Complete
interrupt. Since INTMASK was already cleared by dw_mci_remove(), Command
Complete interrupt is not reaching the system. This leads to process hung.

Signed-off-by: Prabu Thangamuthu <prabu.t@...opsys.com>
---
Change log v2:
	-Added prefix "mmc:" to the commit message header.
	-Updated the Commit Message.

 drivers/mmc/host/dw_mmc.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 55179f1..40e9d8e 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -2926,15 +2926,15 @@ void dw_mci_remove(struct dw_mci *host)
 {
 	int i;
 
-	mci_writel(host, RINTSTS, 0xFFFFFFFF);
-	mci_writel(host, INTMASK, 0); /* disable all mmc interrupt first */
-
 	for (i = 0; i < host->num_slots; i++) {
 		dev_dbg(host->dev, "remove slot %d\n", i);
 		if (host->slot[i])
 			dw_mci_cleanup_slot(host->slot[i], i);
 	}
 
+	mci_writel(host, RINTSTS, 0xFFFFFFFF);
+	mci_writel(host, INTMASK, 0); /* disable all mmc interrupt first */
+
 	/* disable clock to CIU */
 	mci_writel(host, CLKENA, 0);
 	mci_writel(host, CLKSRC, 0);
-- 
1.7.6.5
--
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