diff mbox

[v3,1/4] mmc: sdhci: fix interrupt storm from card detection

Message ID 1308566325-11600-2-git-send-email-shawn.guo@linaro.org (mailing list archive)
State New, archived
Headers show

Commit Message

Shawn Guo June 20, 2011, 10:38 a.m. UTC
The issue was initially found by Eric Benard as below.

http://permalink.gmane.org/gmane.linux.ports.arm.kernel/108031

Not sure about other SDHCI based controller, but on Freescale eSDHC,
the SDHCI_INT_CARD_INSERT bits will be immediately set again when it
gets cleared, if a card is inserted. The driver need to mask the irq
to prevent interrupt storm which will freeze the system.  And the
SDHCI_INT_CARD_REMOVE gets the same situation.

The patch fixes the problem based on the initial idea from
Eric Benard.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Cc: Eric Benard <eric@eukrea.com>
---
 drivers/mmc/host/sdhci.c |   27 +++++++++++++++++++++++----
 1 files changed, 23 insertions(+), 4 deletions(-)

Comments

Philip Rakity June 20, 2011, 3:59 p.m. UTC | #1
On Jun 20, 2011, at 3:38 AM, Shawn Guo wrote:

> The issue was initially found by Eric Benard as below.
> 
> http://permalink.gmane.org/gmane.linux.ports.arm.kernel/108031
> 
> Not sure about other SDHCI based controller, but on Freescale eSDHC,
> the SDHCI_INT_CARD_INSERT bits will be immediately set again when it
> gets cleared, if a card is inserted. The driver need to mask the irq
> to prevent interrupt storm which will freeze the system.  And the
> SDHCI_INT_CARD_REMOVE gets the same situation.
> 
> The patch fixes the problem based on the initial idea from
> Eric Benard.
> 
> Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
> Cc: Eric Benard <eric@eukrea.com>
> ---
> drivers/mmc/host/sdhci.c |   27 +++++++++++++++++++++++----
> 1 files changed, 23 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 91d9892..d94e2b4 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -127,7 +127,9 @@ static void sdhci_mask_irqs(struct sdhci_host *host, u32 irqs)
> 
> static void sdhci_set_card_detection(struct sdhci_host *host, bool enable)
> {
> -	u32 irqs = SDHCI_INT_CARD_REMOVE | SDHCI_INT_CARD_INSERT;
> +	u32 present = sdhci_readl(host, SDHCI_PRESENT_STATE) &
> +		      SDHCI_CARD_PRESENT;
> +	u32 irqs = present ? SDHCI_INT_CARD_REMOVE : SDHCI_INT_CARD_INSERT;
> 
> 	if (host->quirks & SDHCI_QUIRK_BROKEN_CARD_DETECTION)
> 		return;


Accessing off chip registers is slow.  It would be better to check for the quirk first
and then read the present state register.

eg
	
	u32 present;
	u32 irqs;	

> 	if (host->quirks & SDHCI_QUIRK_BROKEN_CARD_DETECTION)
> 		return;

>  	present = sdhci_readl(host, SDHCI_PRESENT_STATE) &
> 		      SDHCI_CARD_PRESENT;


> 	irqs = present ? SDHCI_INT_CARD_REMOVE : SDHCI_INT_CARD_INSERT;


Philip
Shawn Guo June 21, 2011, 1:34 a.m. UTC | #2
On Mon, Jun 20, 2011 at 08:59:38AM -0700, Philip Rakity wrote:
> 
> On Jun 20, 2011, at 3:38 AM, Shawn Guo wrote:
> 
> > The issue was initially found by Eric Benard as below.
> > 
> > http://permalink.gmane.org/gmane.linux.ports.arm.kernel/108031
> > 
> > Not sure about other SDHCI based controller, but on Freescale eSDHC,
> > the SDHCI_INT_CARD_INSERT bits will be immediately set again when it
> > gets cleared, if a card is inserted. The driver need to mask the irq
> > to prevent interrupt storm which will freeze the system.  And the
> > SDHCI_INT_CARD_REMOVE gets the same situation.
> > 
> > The patch fixes the problem based on the initial idea from
> > Eric Benard.
> > 
> > Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
> > Cc: Eric Benard <eric@eukrea.com>
> > ---
> > drivers/mmc/host/sdhci.c |   27 +++++++++++++++++++++++----
> > 1 files changed, 23 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> > index 91d9892..d94e2b4 100644
> > --- a/drivers/mmc/host/sdhci.c
> > +++ b/drivers/mmc/host/sdhci.c
> > @@ -127,7 +127,9 @@ static void sdhci_mask_irqs(struct sdhci_host *host, u32 irqs)
> > 
> > static void sdhci_set_card_detection(struct sdhci_host *host, bool enable)
> > {
> > -	u32 irqs = SDHCI_INT_CARD_REMOVE | SDHCI_INT_CARD_INSERT;
> > +	u32 present = sdhci_readl(host, SDHCI_PRESENT_STATE) &
> > +		      SDHCI_CARD_PRESENT;
> > +	u32 irqs = present ? SDHCI_INT_CARD_REMOVE : SDHCI_INT_CARD_INSERT;
> > 
> > 	if (host->quirks & SDHCI_QUIRK_BROKEN_CARD_DETECTION)
> > 		return;
> 
> 
> Accessing off chip registers is slow.  It would be better to check for the quirk first
> and then read the present state register.
> 
> eg
> 	
> 	u32 present;
> 	u32 irqs;	
> 
> > 	if (host->quirks & SDHCI_QUIRK_BROKEN_CARD_DETECTION)
> > 		return;
> 
> >  	present = sdhci_readl(host, SDHCI_PRESENT_STATE) &
> > 		      SDHCI_CARD_PRESENT;
> 
> 
> > 	irqs = present ? SDHCI_INT_CARD_REMOVE : SDHCI_INT_CARD_INSERT;
> 
Makes sense.  Will do.
diff mbox

Patch

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 91d9892..d94e2b4 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -127,7 +127,9 @@  static void sdhci_mask_irqs(struct sdhci_host *host, u32 irqs)
 
 static void sdhci_set_card_detection(struct sdhci_host *host, bool enable)
 {
-	u32 irqs = SDHCI_INT_CARD_REMOVE | SDHCI_INT_CARD_INSERT;
+	u32 present = sdhci_readl(host, SDHCI_PRESENT_STATE) &
+		      SDHCI_CARD_PRESENT;
+	u32 irqs = present ? SDHCI_INT_CARD_REMOVE : SDHCI_INT_CARD_INSERT;
 
 	if (host->quirks & SDHCI_QUIRK_BROKEN_CARD_DETECTION)
 		return;
@@ -2154,13 +2156,30 @@  static irqreturn_t sdhci_irq(int irq, void *dev_id)
 		mmc_hostname(host->mmc), intmask);
 
 	if (intmask & (SDHCI_INT_CARD_INSERT | SDHCI_INT_CARD_REMOVE)) {
+		u32 present = sdhci_readl(host, SDHCI_PRESENT_STATE) &
+			      SDHCI_CARD_PRESENT;
+
+		/*
+		 * There is a observation on i.mx esdhc.  INSERT bit will be
+		 * immediately set again when it gets cleared, if a card is
+		 * inserted.  We have to mask the irq to prevent interrupt
+		 * storm which will freeze the system.  And the REMOVE gets
+		 * the same situation.
+		 *
+		 * More testing are needed here to ensure it works for other
+		 * platforms though.
+		 */
+		sdhci_mask_irqs(host, present ? SDHCI_INT_CARD_INSERT :
+						SDHCI_INT_CARD_REMOVE);
+		sdhci_unmask_irqs(host, present ? SDHCI_INT_CARD_REMOVE :
+						  SDHCI_INT_CARD_INSERT);
+
 		sdhci_writel(host, intmask & (SDHCI_INT_CARD_INSERT |
-			SDHCI_INT_CARD_REMOVE), SDHCI_INT_STATUS);
+			     SDHCI_INT_CARD_REMOVE), SDHCI_INT_STATUS);
+		intmask &= ~(SDHCI_INT_CARD_INSERT | SDHCI_INT_CARD_REMOVE);
 		tasklet_schedule(&host->card_tasklet);
 	}
 
-	intmask &= ~(SDHCI_INT_CARD_INSERT | SDHCI_INT_CARD_REMOVE);
-
 	if (intmask & SDHCI_INT_CMD_MASK) {
 		sdhci_writel(host, intmask & SDHCI_INT_CMD_MASK,
 			SDHCI_INT_STATUS);