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@xxxxxxxxxx> > > Cc: Eric Benard <eric@xxxxxxxxxx> > > --- > > 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. -- Regards, Shawn -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
