linux-kernel - Re: [PATCH V3] MMC: PM: add suspend/resume in atmel-mci

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Date:	Mon, 4 Jul 2011 14:06:52 +0300
From:	Felipe Balbi <balbi@...com>
To:	Nicolas Ferre <nicolas.ferre@...el.com>
Cc:	cjb@...top.org, linux-mmc@...r.kernel.org,
	hans-christian.egtvedt@...el.com, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, kernel@...32linux.org,
	u.kleine-koenig@...gutronix.de
Subject: Re: [PATCH V3] MMC: PM: add suspend/resume in atmel-mci

Hi,

On Mon, Jul 04, 2011 at 01:38:25PM +0200, Nicolas Ferre wrote:
> Take care of slots while going to suspend state.
> 
> Signed-off-by: Nicolas Ferre <nicolas.ferre@...el.com>
> ---
> V3: take care of each slot SUSPENDED state
>     (adding a status bit in the slot "flags")
> V2: move to pm_ops
> 
>  drivers/mmc/host/atmel-mci.c |   60 ++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 60 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/mmc/host/atmel-mci.c b/drivers/mmc/host/atmel-mci.c
> index aa8039f..ed63bcd 100644
> --- a/drivers/mmc/host/atmel-mci.c
> +++ b/drivers/mmc/host/atmel-mci.c
> @@ -203,6 +203,7 @@ struct atmel_mci_slot {
>  #define ATMCI_CARD_PRESENT	0
>  #define ATMCI_CARD_NEED_INIT	1
>  #define ATMCI_SHUTDOWN		2
> +#define ATMCI_SUSPENDED		3
>  
>  	int			detect_pin;
>  	int			wp_pin;
> @@ -1878,10 +1879,69 @@ static int __exit atmci_remove(struct platform_device *pdev)
>  	return 0;
>  }
>  
> +#ifdef CONFIG_PM
> +static int atmci_suspend(struct device *dev)
> +{
> +	struct atmel_mci *host = dev_get_drvdata(dev);
> +	int i;
> +
> +	 for (i = 0; i < ATMEL_MCI_MAX_NR_SLOTS; i++) {
> +		struct atmel_mci_slot *slot = host->slot[i];
> +		int ret;
> +
> +		if (!slot)
> +			continue;
> +		ret = mmc_suspend_host(slot->mmc);
> +		if (ret < 0) {
> +			while (--i >= 0) {
> +				slot = host->slot[i];
> +				if (slot
> +				&& test_bit(ATMCI_SUSPENDED, &slot->flags)) {
> +					mmc_resume_host(host->slot[i]->mmc);
> +					clear_bit(ATMCI_SUSPENDED, &slot->flags);
> +				}
> +			}
> +			return ret;
> +		} else {
> +			set_bit(ATMCI_SUSPENDED, &slot->flags);
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static int atmci_resume(struct device *dev)
> +{
> +	struct atmel_mci *host = dev_get_drvdata(dev);
> +	int i;
> +	int ret = 0;
> +
> +	for (i = 0; i < ATMEL_MCI_MAX_NR_SLOTS; i++) {
> +		struct atmel_mci_slot *slot = host->slot[i];
> +		int err;
> +
> +		slot = host->slot[i];
> +		if (!slot)
> +			continue;
> +		if (!test_bit(ATMCI_SUSPENDED, &slot->flags))
> +			continue;
> +		err = mmc_resume_host(slot->mmc);
> +		if (err < 0)
> +			ret = err;
> +		else
> +			clear_bit(ATMCI_SUSPENDED, &slot->flags);
> +	}
> +
> +	return ret;
> +}
> +#endif
> +static SIMPLE_DEV_PM_OPS(atmci_pm, atmci_suspend, atmci_resume);

if you disable CONFIG_PM this won't work. atmci_resume and atmci_suspend
will be undefined.

>  static struct platform_driver atmci_driver = {
>  	.remove		= __exit_p(atmci_remove),
>  	.driver		= {
>  		.name		= "atmel_mci",
> +		.pm		= &atmci_pm,

this pointer will also be invalid.

what most people do is:

#ifdef CONFIG_PM

suspend()
resume()

static SIMPLE_DEV_PM_OPS(atmci_pm, suspend, resume);

#define DEV_PM_OPS	(&atmci_pm)
#else
#define DEV_PM_OPS	NULL
#endif

-- 
balbi

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