linux-kernel - Re: [PATCH RESEND] mmc: Delay the card_event callback into the mmc

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Date:	Wed, 9 Apr 2014 10:56:36 +0200
From:	Ulf Hansson <ulf.hansson@...aro.org>
To:	Markus Mayer <markus.mayer@...aro.org>
Cc:	Chris Ball <chris@...ntf.net>, Christian Daudt <bcm@...thebug.org>,
	Linux MMC List <linux-mmc@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RESEND] mmc: Delay the card_event callback into the
 mmc_rescan worker

On 9 April 2014 00:19, Markus Mayer <markus.mayer@...aro.org> wrote:
> This change removes the callback from atomic context which it doesn't
> need to be in, and puts it in line with the debounced rescan.
>
> This code is based on these e-mail threads with Christian Daudt:
>
>   https://lkml.org/lkml/2013/8/19/539
>   https://lkml.org/lkml/2014/3/19/79
>
> Signed-off-by: Markus Mayer <markus.mayer@...aro.org>
> ---
>  drivers/mmc/core/core.c      |    5 +++++
>  drivers/mmc/core/slot-gpio.c |    4 +---
>  include/linux/mmc/host.h     |    2 ++
>  3 files changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 098374b..ff7fd2e 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -2421,6 +2421,11 @@ void mmc_rescan(struct work_struct *work)
>                 container_of(work, struct mmc_host, detect.work);
>         int i;
>
> +       if (host->trigger_card_event && host->ops->card_event) {
> +               host->ops->card_event(host);
> +               host->trigger_card_event = false;
> +       }
> +

So this might be a stupid question. :-)

Could you elaborate on why the host->ops->card_event then is needed at
all. Why can't host drivers use host->ops->get_cd to perform the
actions they need?

The reason for bringing this up, is because this patch moves the
invokes of the these callbacks quite close to each other. Earlier they
were more separated.

Kind regards
Ulf Hansson

>         if (host->rescan_disable)
>                 return;
>
> diff --git a/drivers/mmc/core/slot-gpio.c b/drivers/mmc/core/slot-gpio.c
> index 46596b71..4029c85 100644
> --- a/drivers/mmc/core/slot-gpio.c
> +++ b/drivers/mmc/core/slot-gpio.c
> @@ -29,9 +29,7 @@ static irqreturn_t mmc_gpio_cd_irqt(int irq, void *dev_id)
>         /* Schedule a card detection after a debounce timeout */
>         struct mmc_host *host = dev_id;
>
> -       if (host->ops->card_event)
> -               host->ops->card_event(host);
> -
> +       host->trigger_card_event = true;
>         mmc_detect_change(host, msecs_to_jiffies(200));
>
>         return IRQ_HANDLED;
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index 99f5709..63b983b 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -322,6 +322,8 @@ struct mmc_host {
>         int                     rescan_disable; /* disable card detection */
>         int                     rescan_entered; /* used with nonremovable devices */
>
> +       bool                    trigger_card_event; /* card_event necessary */
> +
>         struct mmc_card         *card;          /* device attached to this host */
>
>         wait_queue_head_t       wq;
> --
> 1.7.9.5
>
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