On Fri, 2011-06-03 at 00:13 +0100, Daniel Drake wrote:
> Commit 06e8935febe687e2a561707d4c7ca4245d261dbe adds an IRQ handling
> optimization for single-function SDIO cards like this one, but at the
> same time exposes a small hardware bug.
>
> During hardware init, an interrupt is generated with (apparently) no
> source. Previously, mmc threw this interrupt away, but now (due to the
> optimization), the mmc layer passes this onto libertas, before it is ready
> (and before it has enabled interrupts), causing a crash.
>
> Work around this hardware bug by registering the IRQ handler later and
> making it capable of handling interrupts with no cause. The change that
> makes the IRQ handler registration happen later actually eliminates
> the spurious interrupt as well.
>
> Signed-off-by: Daniel Drake <dsd@xxxxxxxxxx>
Acked-by: Dan Williams <dcbw@xxxxxxxxxx>
> ---
> drivers/net/wireless/libertas/if_sdio.c | 21 ++++++++++++++++-----
> 1 files changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/net/wireless/libertas/if_sdio.c b/drivers/net/wireless/libertas/if_sdio.c
> index a7b5cb0..224e985 100644
> --- a/drivers/net/wireless/libertas/if_sdio.c
> +++ b/drivers/net/wireless/libertas/if_sdio.c
> @@ -907,7 +907,7 @@ static void if_sdio_interrupt(struct sdio_func *func)
> card = sdio_get_drvdata(func);
>
> cause = sdio_readb(card->func, IF_SDIO_H_INT_STATUS, &ret);
> - if (ret)
> + if (ret || !cause)
> goto out;
>
> lbs_deb_sdio("interrupt: 0x%X\n", (unsigned)cause);
> @@ -1008,10 +1008,6 @@ static int if_sdio_probe(struct sdio_func *func,
> if (ret)
> goto release;
>
> - ret = sdio_claim_irq(func, if_sdio_interrupt);
> - if (ret)
> - goto disable;
> -
> /* For 1-bit transfers to the 8686 model, we need to enable the
> * interrupt flag in the CCCR register. Set the MMC_QUIRK_LENIENT_FN0
> * bit to allow access to non-vendor registers. */
> @@ -1083,6 +1079,21 @@ static int if_sdio_probe(struct sdio_func *func,
> card->rx_unit = 0;
>
> /*
> + * Set up the interrupt handler late.
> + *
> + * If we set it up earlier, the (buggy) hardware generates a spurious
> + * interrupt, even before the interrupt has been enabled, with
> + * CCCR_INTx = 0.
> + *
> + * We register the interrupt handler late so that we can handle any
> + * spurious interrupts, and also to avoid generation of that known
> + * spurious interrupt in the first place.
> + */
> + ret = sdio_claim_irq(func, if_sdio_interrupt);
> + if (ret)
> + goto disable;
> +
> + /*
> * Enable interrupts now that everything is set up
> */
> sdio_writeb(func, 0x0f, IF_SDIO_H_INT_MASK, &ret);
--
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