[PATCH v5] sdio: optimized SDIO IRQ handling for single irq

[Daniel Mack]

On Mon, Jun 6, 2011 at 3:17 PM, Daniel Mack <zonque at gmail.com> wrote:
> On Wed, May 11, 2011 at 6:45 PM, Chris Ball <cjb at laptop.org> wrote:
>> Hi Per,
>>
>> On Wed, May 11 2011, Per Forlin wrote:
>>> From: Stefan Nilsson XK <stefan.xk.nilsson at stericsson.com>
>>>
>>> If there is only 1 function interrupt registered it is possible to
>>> improve performance by directly calling the irq handler
>>> and avoiding the overhead of reading the CCCR registers.
>>>
>>> Signed-off-by: Per Forlin <per.forlin at linaro.org>
>>> Acked-by: Ulf Hansson <ulf.hansson at stericsson.com>
>>> Reviewed-by: Nicolas Pitre <nicolas.pitre at linaro.org>
>>> ---
>>>  drivers/mmc/core/sdio_irq.c |   33 ++++++++++++++++++++++++++++++++-
>>>  include/linux/mmc/card.h    |    1 +
>>>  2 files changed, 33 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/drivers/mmc/core/sdio_irq.c b/drivers/mmc/core/sdio_irq.c
>>> index bb192f9..a0890ac 100644
>>> --- a/drivers/mmc/core/sdio_irq.c
>>> +++ b/drivers/mmc/core/sdio_irq.c
>>> @@ -31,6 +31,17 @@ static int process_sdio_pending_irqs(struct mmc_card *card)
>>>  {
>>>       int i, ret, count;
>>>       unsigned char pending;
>>> +     struct sdio_func *func;
>>> +
>>> +     /*
>>> +      * Optimization, if there is only 1 function interrupt registered
>>> +      * call irq handler directly
>>> +      */
>>> +     func = card->sdio_single_irq;
>>> +     if (func) {
>>> +             func->irq_handler(func);
>>> +             return 1;
>>> +     }
>>>
>>>       ret = mmc_io_rw_direct(card, 0, 0, SDIO_CCCR_INTx, 0, &pending);
>>>       if (ret) {
>>> @@ -42,7 +53,7 @@ static int process_sdio_pending_irqs(struct mmc_card *card)
>>>       count = 0;
>>>       for (i = 1; i <= 7; i++) {
>>>               if (pending & (1 << i)) {
>>> -                     struct sdio_func *func = card->sdio_func[i - 1];
>>> +                     func = card->sdio_func[i - 1];
>>>                       if (!func) {
>>>                               printk(KERN_WARNING "%s: pending IRQ for "
>>>                                       "non-existant function\n",
>>> @@ -186,6 +197,24 @@ static int sdio_card_irq_put(struct mmc_card *card)
>>>       return 0;
>>>  }
>>>
>>> +/* If there is only 1 function registered set sdio_single_irq */
>>> +static void sdio_single_irq_set(struct mmc_card *card)
>>> +{
>>> +     struct sdio_func *func;
>>> +     int i;
>>> +
>>> +     card->sdio_single_irq = NULL;
>>> +     if ((card->host->caps & MMC_CAP_SDIO_IRQ) &&
>>> +         card->host->sdio_irqs == 1)
>>> +             for (i = 0; i < card->sdio_funcs; i++) {
>>> +                    func = card->sdio_func[i];
>>> +                    if (func && func->irq_handler) {
>>> +                            card->sdio_single_irq = func;
>>> +                            break;
>>> +                    }
>>> +            }
>>> +}
>>> +
>>>  /**
>>>   *   sdio_claim_irq - claim the IRQ for a SDIO function
>>>   *   @func: SDIO function
>>> @@ -227,6 +256,7 @@ int sdio_claim_irq(struct sdio_func *func, sdio_irq_handler_t *handler)
>>>       ret = sdio_card_irq_get(func->card);
>>>       if (ret)
>>>               func->irq_handler = NULL;
>>> +     sdio_single_irq_set(func->card);
>>>
>>>       return ret;
>>>  }
>>> @@ -251,6 +281,7 @@ int sdio_release_irq(struct sdio_func *func)
>>>       if (func->irq_handler) {
>>>               func->irq_handler = NULL;
>>>               sdio_card_irq_put(func->card);
>>> +             sdio_single_irq_set(func->card);
>>>       }
>>>
>>>       ret = mmc_io_rw_direct(func->card, 0, 0, SDIO_CCCR_IENx, 0, &reg);
>>> diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
>>> index d8dffc9..4910dec 100644
>>> --- a/include/linux/mmc/card.h
>>> +++ b/include/linux/mmc/card.h
>>> @@ -191,6 +191,7 @@ struct mmc_card {
>>>       struct sdio_cccr        cccr;           /* common card info */
>>>       struct sdio_cis         cis;            /* common tuple info */
>>>       struct sdio_func        *sdio_func[SDIO_MAX_FUNCS]; /* SDIO functions (devices) */
>>> +     struct sdio_func        *sdio_single_irq; /* SDIO function when only one IRQ active */
>>>       unsigned                num_info;       /* number of info strings */
>>>       const char              **info;         /* info strings */
>>>       struct sdio_func_tuple  *tuples;        /* unknown common tuples */
>>
>> Thanks, looks good now -- pushed to mmc-next for .40.
>
> This patch breaks libertas over SDIO, as the interrupt handler of that
> driver is now called even though the hardware didn't signal any
> interrupt condition. This is a problem for at least two reasons in
> this case:

I checked the libertas-dev archives too late and saw that there is a
fix by Daniel Drake for this problem already.

Sorry for the noise.

Daniel