[PATCH v4 1/4] mmc: sdhci: fix interrupt storm from card detection

[Shawn Guo]

On Tue, Jun 21, 2011 at 09:05:25AM -0700, Philip Rakity wrote:
> 
> On Jun 21, 2011, at 7:41 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 at linaro.org>
> > Cc: Eric Benard <eric at eukrea.com>
> > Tested-by: Arnaud Patard <arnaud.patard at rtp-net.org>
> > ---
> > drivers/mmc/host/sdhci.c |   29 +++++++++++++++++++++++++----
> > 1 files changed, 25 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> > index 91d9892..790f959 100644
> > --- a/drivers/mmc/host/sdhci.c
> > +++ b/drivers/mmc/host/sdhci.c
> > @@ -127,11 +127,15 @@ 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, 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;
> > +
> > 	if (enable)
> > 		sdhci_unmask_irqs(host, irqs);
> > 	else
> > @@ -2154,13 +2158,30 @@ 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);
> 
> ====
> Please keep the old formatting since code does not change anything.  Makes it easier to find
> the real change
> 

I actually rewrote the body of the if-statement, and fixed one
indentation in that specific line.

> > +		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);
> > -- 
> > 1.7.4.1
> > 
> 
> 
> Reviewed-by: Philip Rakity <prakity at marvell.com>
> 

-- 
Regards,
Shawn