Re: [PATCH] mmc: sdio: avoid spurious calls to interrupt handlers

["Sujit Reddy Thumma" <sthumma@codeaurora.org>]

Hi Nicolas,

>
> Commit 06e8935feb "optimized SDIO IRQ handling for single irq"
> introduced some spurious calls to SDIO function interrupt handlers,
> such as when the SDIO IRQ thread is started, or the safety check
> performed upon a system resume.  Let's add a flag to perform the
> optimization only when a real interrupt is signaled by the host
> driver and we know there is no point confirming it.
>

Thanks for putting up formal patch.

> Reported-by: Sujit Reddy Thumma <sthumma@codeaurora.org>
> Signed-off-by: Nicolas Pitre <nico@linaro.org>
> Cc: stable@kernel.org
>
> diff --git a/drivers/mmc/core/sdio_irq.c b/drivers/mmc/core/sdio_irq.c
> index f573e7f9f7..3d8ceb4084 100644
> --- a/drivers/mmc/core/sdio_irq.c
> +++ b/drivers/mmc/core/sdio_irq.c
> @@ -28,18 +28,20 @@
>
>  #include "sdio_ops.h"
>
> -static int process_sdio_pending_irqs(struct mmc_card *card)
> +static int process_sdio_pending_irqs(struct mmc_host *host)
>  {
> +	struct mmc_card *card = host->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
> +	 * and we know an IRQ was signaled then call irq handler directly.
> +	 * Otherwise do the full probe.
>  	 */
>  	func = card->sdio_single_irq;
> -	if (func) {
> +	if (func && host->sdio_irq_pending) {
>  		func->irq_handler(func);
>  		return 1;
>  	}
> @@ -116,7 +118,8 @@ static int sdio_irq_thread(void *_host)
>  		ret = __mmc_claim_host(host, &host->sdio_irq_thread_abort);
>  		if (ret)
>  			break;
> -		ret = process_sdio_pending_irqs(host->card);
> +		ret = process_sdio_pending_irqs(host);
> +		host->sdio_irq_pending = false;
>  		mmc_release_host(host);
>
>  		/*
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index ee2b0363c0..557aa4cd66 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -323,6 +323,7 @@ struct mmc_host {
>
>  	unsigned int		sdio_irqs;
>  	struct task_struct	*sdio_irq_thread;
> +	bool			sdio_irq_pending;
>  	atomic_t		sdio_irq_thread_abort;
>
>  	mmc_pm_flag_t		pm_flags;	/* requested pm features */
> @@ -378,6 +379,7 @@ extern int mmc_cache_ctrl(struct mmc_host *, u8);
>  static inline void mmc_signal_sdio_irq(struct mmc_host *host)
>  {
>  	host->ops->enable_sdio_irq(host, 0);
> +	host->sdio_irq_pending = true;
>  	wake_up_process(host->sdio_irq_thread);
>  }

In this case probably we need to add the following:
@@ -946,8 +946,11 @@ static int mmc_sdio_resume(struct mmc_host *host)
                }
        }

-       if (!err && host->sdio_irqs)
-               mmc_signal_sdio_irq(host);
+       if (!err && host->sdio_irqs) {
+               host->ops->enable_sdio_irq(host, 0);
+               wake_up_process(host->sdio_irq_thread);
+       }

>
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-- 
Thanks & Regards,
Sujit Reddy Thumma

Consultant for Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum.