I have encountered an interrupt storm during the eMMC chip probing (and
the chip finally didn't get detected).  It turned out that U-Boot left
the DMAC interrupts enabled while the Linux driver  didn't use those.
The SDHI driver's interrupt handler somehow assumes that, even if an
SDIO interrupt didn't happen, it should return IRQ_HANDLED.  I think
that if none of the enabled interrupts happened and got handled, we
should return IRQ_NONE -- that way the kernel IRQ code recoginizes
a spurious interrupt and masks it off pretty quickly...

Fixes: 7729c7a232a9 ("mmc: tmio: Provide separate interrupt handlers")
Signed-off-by: Sergei Shtylyov <sergei.shtyl...@cogentembedded.com>

---
The patch is against Ulf Hansson's 'mmc.git' repo's 'fixes' branch.

Changes in version 3:
- simplified the final *return* statement in __tmio_mmc_sdio_irq();
- added the "Fixes:" tag;
- cleaned up the whitespace in the patch description.

Changes in version 2:
- refreshed the patch;
- fixed an article and whitespace in the patch description.

 drivers/mmc/host/tmio_mmc_core.c |   11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

Index: mmc/drivers/mmc/host/tmio_mmc_core.c
===================================================================
--- mmc.orig/drivers/mmc/host/tmio_mmc_core.c
+++ mmc/drivers/mmc/host/tmio_mmc_core.c
@@ -629,7 +629,7 @@ static bool __tmio_mmc_sdcard_irq(struct
        return false;
 }
 
-static void __tmio_mmc_sdio_irq(struct tmio_mmc_host *host)
+static bool __tmio_mmc_sdio_irq(struct tmio_mmc_host *host)
 {
        struct mmc_host *mmc = host->mmc;
        struct tmio_mmc_data *pdata = host->pdata;
@@ -637,7 +637,7 @@ static void __tmio_mmc_sdio_irq(struct t
        unsigned int sdio_status;
 
        if (!(pdata->flags & TMIO_MMC_SDIO_IRQ))
-               return;
+               return false;
 
        status = sd_ctrl_read16(host, CTL_SDIO_STATUS);
        ireg = status & TMIO_SDIO_MASK_ALL & ~host->sdio_irq_mask;
@@ -650,6 +650,8 @@ static void __tmio_mmc_sdio_irq(struct t
 
        if (mmc->caps & MMC_CAP_SDIO_IRQ && ireg & TMIO_SDIO_STAT_IOIRQ)
                mmc_signal_sdio_irq(mmc);
+
+       return ireg;
 }
 
 irqreturn_t tmio_mmc_irq(int irq, void *devid)
@@ -668,9 +670,10 @@ irqreturn_t tmio_mmc_irq(int irq, void *
        if (__tmio_mmc_sdcard_irq(host, ireg, status))
                return IRQ_HANDLED;
 
-       __tmio_mmc_sdio_irq(host);
+       if (__tmio_mmc_sdio_irq(host))
+               return IRQ_HANDLED;
 
-       return IRQ_HANDLED;
+       return IRQ_NONE;
 }
 EXPORT_SYMBOL_GPL(tmio_mmc_irq);
 

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