[PATCH 01/38] mmc: sdio_irq: rework sdio irq handling

[Ulf Hansson]

On 23 April 2014 21:06, Russell King <rmk+kernel at arm.linux.org.uk> wrote:
> Rather than the SDIO support spawning it's own thread for handling card
> interrupts, use the generic IRQ infrastructure for this, triggering it
> from the host interface's interrupt handling directly.
>
> This avoids a race between the parent thread waiting to receive an
> interrupt response from the card, and the slow startup from the sdio
> irq thread, which can occur as a result of high system load (eg, while
> udev is running.)
>
> Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
> ---
>  drivers/mmc/core/sdio_irq.c | 41 +++++++++++++++++++++++++++++++----------
>  include/linux/mmc/host.h    |  3 +++
>  2 files changed, 34 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/mmc/core/sdio_irq.c b/drivers/mmc/core/sdio_irq.c
> index aaa90460ed23..f23d73993dc6 100644
> --- a/drivers/mmc/core/sdio_irq.c
> +++ b/drivers/mmc/core/sdio_irq.c
> @@ -90,6 +90,15 @@ static int process_sdio_pending_irqs(struct mmc_host *host)
>         return ret;
>  }
>
> +void sdio_run_irqs(struct mmc_host *host)
> +{
> +       mmc_claim_host(host);
> +       host->sdio_irq_pending = true;
> +       process_sdio_pending_irqs(host);
> +       mmc_release_host(host);
> +}
> +EXPORT_SYMBOL_GPL(sdio_run_irqs);
> +
>  static int sdio_irq_thread(void *_host)
>  {
>         struct mmc_host *host = _host;
> @@ -189,14 +198,20 @@ static int sdio_card_irq_get(struct mmc_card *card)
>         WARN_ON(!host->claimed);
>
>         if (!host->sdio_irqs++) {
> -               atomic_set(&host->sdio_irq_thread_abort, 0);
> -               host->sdio_irq_thread =
> -                       kthread_run(sdio_irq_thread, host, "ksdioirqd/%s",
> -                               mmc_hostname(host));
> -               if (IS_ERR(host->sdio_irq_thread)) {
> -                       int err = PTR_ERR(host->sdio_irq_thread);
> -                       host->sdio_irqs--;
> -                       return err;
> +               if (!(host->caps2 & MMC_CAP2_SDIO_NOTHREAD)) {
> +                       atomic_set(&host->sdio_irq_thread_abort, 0);
> +                       host->sdio_irq_thread =
> +                               kthread_run(sdio_irq_thread, host,
> +                                           "ksdioirqd/%s", mmc_hostname(host));
> +                       if (IS_ERR(host->sdio_irq_thread)) {
> +                               int err = PTR_ERR(host->sdio_irq_thread);
> +                               host->sdio_irqs--;
> +                               return err;
> +                       }
> +               } else {

I suppose you need to check for MMC_CAP_SDIO_IRQ here?

> +                       mmc_host_clk_hold(host);
> +                       host->ops->enable_sdio_irq(host, 1);
> +                       mmc_host_clk_release(host);
>                 }
>         }
>
> @@ -211,8 +226,14 @@ static int sdio_card_irq_put(struct mmc_card *card)
>         BUG_ON(host->sdio_irqs < 1);
>
>         if (!--host->sdio_irqs) {
> -               atomic_set(&host->sdio_irq_thread_abort, 1);
> -               kthread_stop(host->sdio_irq_thread);
> +               if (!(host->caps2 & MMC_CAP2_SDIO_NOTHREAD)) {
> +                       atomic_set(&host->sdio_irq_thread_abort, 1);
> +                       kthread_stop(host->sdio_irq_thread);
> +               } else {

I suppose you need to check for MMC_CAP_SDIO_IRQ here?

> +                       mmc_host_clk_hold(host);
> +                       host->ops->enable_sdio_irq(host, 0);
> +                       mmc_host_clk_release(host);
> +               }
>         }
>
>         return 0;
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index cb61ea4d6945..28c5e796292f 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -278,6 +278,7 @@ struct mmc_host {
>  #define MMC_CAP2_PACKED_CMD    (MMC_CAP2_PACKED_RD | \
>                                  MMC_CAP2_PACKED_WR)
>  #define MMC_CAP2_NO_PRESCAN_POWERUP (1 << 14)  /* Don't power up before scan */
> +#define MMC_CAP2_SDIO_NOTHREAD (1 << 15)
>
>         mmc_pm_flag_t           pm_caps;        /* supported pm features */
>
> @@ -391,6 +392,8 @@ static inline void mmc_signal_sdio_irq(struct mmc_host *host)
>         wake_up_process(host->sdio_irq_thread);
>  }
>
> +void sdio_run_irqs(struct mmc_host *host);
> +
>  #ifdef CONFIG_REGULATOR
>  int mmc_regulator_get_ocrmask(struct regulator *supply);
>  int mmc_regulator_set_ocr(struct mmc_host *mmc,
> --
> 1.8.3.1

Kind regards
Ulf Hansson

>
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