Re: [PATCH 1/32] mmc: add 'enable' and 'disable' methods to mmc host

From: Linus Walleij
Date: Thu Jul 23 2009 - 16:37:28 EST

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Acked-by: Linus Walleij <linus.walleij@xxxxxxxxxxxxxx>

And please drop my other patch in favor of this one then.

Linus Walleij

2009/7/10 Adrian Hunter <adrian.hunter@xxxxxxxxx>:
> From a0164897276e4d1f972fd90b1e9499e1ab8d221e Mon Sep 17 00:00:00 2001
> From: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> Date: Wed, 22 Apr 2009 12:50:45 +0300
> Subject: [PATCH] mmc: add 'enable' and 'disable' methods to mmc host
>
> MMC hosts that support power saving can use the 'enable' and
> 'disable' methods to exit and enter power saving states.
> An explanation of their use is provided in the comments
> added to include/linux/mmc/host.h.
>
> Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> ---
> drivers/mmc/core/core.c | 174 ++++++++++++++++++++++++++++++++++++++++++++--
> drivers/mmc/core/host.c | 1 +
> drivers/mmc/core/host.h | 2 +
> include/linux/mmc/host.h | 47 ++++++++++++
> 4 files changed, 218 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index d84c880..41fd127 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -344,6 +344,98 @@ unsigned int mmc_align_data_size(struct mmc_card *card, unsigned int sz)
> EXPORT_SYMBOL(mmc_align_data_size);
>
> /**
> + * mmc_host_enable - enable a host.
> + * @host: mmc host to enable
> + *
> + * Hosts that support power saving can use the 'enable' and 'disable'
> + * methods to exit and enter power saving states. For more information
> + * see comments for struct mmc_host_ops.
> + */
> +int mmc_host_enable(struct mmc_host *host)
> +{
> + if (!(host->caps & MMC_CAP_DISABLE))
> + return 0;
> +
> + if (host->en_dis_recurs)
> + return 0;
> +
> + if (host->nesting_cnt++)
> + return 0;
> +
> + cancel_delayed_work_sync(&host->disable);
> +
> + if (host->enabled)
> + return 0;
> +
> + if (host->ops->enable) {
> + int err;
> +
> + host->en_dis_recurs = 1;
> + err = host->ops->enable(host);
> + host->en_dis_recurs = 0;
> +
> + if (err) {
> + pr_debug("%s: enable error %d\n",
> + mmc_hostname(host), err);
> + return err;
> + }
> + }
> + host->enabled = 1;
> + return 0;
> +}
> +EXPORT_SYMBOL(mmc_host_enable);
> +
> +static int mmc_host_do_disable(struct mmc_host *host, int lazy)
> +{
> + if (host->ops->disable) {
> + int err;
> +
> + host->en_dis_recurs = 1;
> + err = host->ops->disable(host, lazy);
> + host->en_dis_recurs = 0;
> +
> + if (err < 0) {
> + pr_debug("%s: disable error %d\n",
> + mmc_hostname(host), err);
> + return err;
> + }
> + if (err > 0)
> + mmc_schedule_delayed_work(&host->disable, err);
> + }
> + host->enabled = 0;
> + return 0;
> +}
> +
> +/**
> + * mmc_host_disable - disable a host.
> + * @host: mmc host to disable
> + *
> + * Hosts that support power saving can use the 'enable' and 'disable'
> + * methods to exit and enter power saving states. For more information
> + * see comments for struct mmc_host_ops.
> + */
> +int mmc_host_disable(struct mmc_host *host)
> +{
> + int err;
> +
> + if (!(host->caps & MMC_CAP_DISABLE))
> + return 0;
> +
> + if (host->en_dis_recurs)
> + return 0;
> +
> + if (--host->nesting_cnt)
> + return 0;
> +
> + if (!host->enabled)
> + return 0;
> +
> + err = mmc_host_do_disable(host, 0);
> + return err;
> +}
> +EXPORT_SYMBOL(mmc_host_disable);
> +
> +/**
> * __mmc_claim_host - exclusively claim a host
> * @host: mmc host to claim
> * @abort: whether or not the operation should be aborted
> @@ -379,11 +471,81 @@ int __mmc_claim_host(struct mmc_host *host, atomic_t *abort)
> wake_up(&host->wq);
> spin_unlock_irqrestore(&host->lock, flags);
> remove_wait_queue(&host->wq, &wait);
> + if (!stop)
> + mmc_host_enable(host);
> return stop;
> }
>
> EXPORT_SYMBOL(__mmc_claim_host);
>
> +static int mmc_try_claim_host(struct mmc_host *host)
> +{
> + int claimed_host = 0;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&host->lock, flags);
> + if (!host->claimed) {
> + host->claimed = 1;
> + claimed_host = 1;
> + }
> + spin_unlock_irqrestore(&host->lock, flags);
> + return claimed_host;
> +}
> +
> +static void mmc_do_release_host(struct mmc_host *host)
> +{
> + unsigned long flags;
> +
> + spin_lock_irqsave(&host->lock, flags);
> + host->claimed = 0;
> + spin_unlock_irqrestore(&host->lock, flags);
> +
> + wake_up(&host->wq);
> +}
> +
> +void mmc_host_deeper_disable(struct work_struct *work)
> +{
> + struct mmc_host *host =
> + container_of(work, struct mmc_host, disable.work);
> +
> + /* If the host is claimed then we do not want to disable it anymore */
> + if (!mmc_try_claim_host(host))
> + return;
> + mmc_host_do_disable(host, 1);
> + mmc_do_release_host(host);
> +}
> +
> +/**
> + * mmc_host_lazy_disable - lazily disable a host.
> + * @host: mmc host to disable
> + *
> + * Hosts that support power saving can use the 'enable' and 'disable'
> + * methods to exit and enter power saving states. For more information
> + * see comments for struct mmc_host_ops.
> + */
> +int mmc_host_lazy_disable(struct mmc_host *host)
> +{
> + if (!(host->caps & MMC_CAP_DISABLE))
> + return 0;
> +
> + if (host->en_dis_recurs)
> + return 0;
> +
> + if (--host->nesting_cnt)
> + return 0;
> +
> + if (!host->enabled)
> + return 0;
> +
> + if (host->disable_delay) {
> + mmc_schedule_delayed_work(&host->disable,
> + msecs_to_jiffies(host->disable_delay));
> + return 0;
> + } else
> + return mmc_host_do_disable(host, 1);
> +}
> +EXPORT_SYMBOL(mmc_host_lazy_disable);
> +
> /**
> * mmc_release_host - release a host
> * @host: mmc host to release
> @@ -393,15 +555,11 @@ EXPORT_SYMBOL(__mmc_claim_host);
> */
> void mmc_release_host(struct mmc_host *host)
> {
> - unsigned long flags;
> -
> WARN_ON(!host->claimed);
>
> - spin_lock_irqsave(&host->lock, flags);
> - host->claimed = 0;
> - spin_unlock_irqrestore(&host->lock, flags);
> + mmc_host_lazy_disable(host);
>
> - wake_up(&host->wq);
> + mmc_do_release_host(host);
> }
>
> EXPORT_SYMBOL(mmc_release_host);
> @@ -947,6 +1105,8 @@ void mmc_stop_host(struct mmc_host *host)
> spin_unlock_irqrestore(&host->lock, flags);
> #endif
>
> + if (host->caps & MMC_CAP_DISABLE)
> + cancel_delayed_work(&host->disable);
> cancel_delayed_work(&host->detect);
> mmc_flush_scheduled_work();
>
> @@ -975,6 +1135,8 @@ void mmc_stop_host(struct mmc_host *host)
> */
> int mmc_suspend_host(struct mmc_host *host, pm_message_t state)
> {
> + if (host->caps & MMC_CAP_DISABLE)
> + cancel_delayed_work(&host->disable);
> cancel_delayed_work(&host->detect);
> mmc_flush_scheduled_work();
>
> diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
> index 5e945e6..a268d12 100644
> --- a/drivers/mmc/core/host.c
> +++ b/drivers/mmc/core/host.c
> @@ -83,6 +83,7 @@ struct mmc_host *mmc_alloc_host(int extra, struct device *dev)
> spin_lock_init(&host->lock);
> init_waitqueue_head(&host->wq);
> INIT_DELAYED_WORK(&host->detect, mmc_rescan);
> + INIT_DELAYED_WORK_DEFERRABLE(&host->disable, mmc_host_deeper_disable);
>
> /*
> * By default, hosts do not support SGIO or large requests.
> diff --git a/drivers/mmc/core/host.h b/drivers/mmc/core/host.h
> index c2dc3d2..8c87e11 100644
> --- a/drivers/mmc/core/host.h
> +++ b/drivers/mmc/core/host.h
> @@ -14,5 +14,7 @@
> int mmc_register_host_class(void);
> void mmc_unregister_host_class(void);
>
> +void mmc_host_deeper_disable(struct work_struct *work);
> +
> #endif
>
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index 3e7615e..583c068 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -51,6 +51,35 @@ struct mmc_ios {
> };
>
> struct mmc_host_ops {
> + /*
> + * Hosts that support power saving can use the 'enable' and 'disable'
> + * methods to exit and enter power saving states. 'enable' is called
> + * when the host is claimed and 'disable' is called (or scheduled with
> + * a delay) when the host is released. The 'disable' is scheduled if
> + * the disable delay set by 'mmc_set_disable_delay()' is non-zero,
> + * otherwise 'disable' is called immediately. 'disable' may be
> + * scheduled repeatedly, to permit ever greater power saving at the
> + * expense of ever greater latency to re-enable. Rescheduling is
> + * determined by the return value of the 'disable' method. A positive
> + * value gives the delay in jiffies.
> + *
> + * In the case where a host function (like set_ios) may be called
> + * with or without the host claimed, enabling and disabling can be
> + * done directly and will nest correctly. Call 'mmc_host_enable()' and
> + * 'mmc_host_lazy_disable()' for this purpose, but note that these
> + * functions must be paired.
> + *
> + * Alternatively, 'mmc_host_enable()' may be paired with
> + * 'mmc_host_disable()' which calls 'disable' immediately. In this
> + * case the 'disable' method will be called with 'lazy' set to 0.
> + * This is mainly useful for error paths.
> + *
> + * Because lazy disble may be called from a work queue, the 'disable'
> + * method must claim the host when 'lazy' != 0, which will work
> + * correctly because recursion is detected and handled.
> + */
> + int (*enable)(struct mmc_host *host);
> + int (*disable)(struct mmc_host *host, int lazy);
> void (*request)(struct mmc_host *host, struct mmc_request *req);
> /*
> * Avoid calling these three functions too often or in a "fast path",
> @@ -118,6 +147,7 @@ struct mmc_host {
> #define MMC_CAP_SPI (1 << 4) /* Talks only SPI protocols */
> #define MMC_CAP_NEEDS_POLL (1 << 5) /* Needs polling for card-detection */
> #define MMC_CAP_8_BIT_DATA (1 << 6) /* Can the host do 8 bit transfers */
> +#define MMC_CAP_DISABLE (1 << 7) /* Can the host be disabled */
>
> /* host specific block data */
> unsigned int max_seg_size; /* see blk_queue_max_segment_size */
> @@ -142,6 +172,13 @@ struct mmc_host {
> unsigned int removed:1; /* host is being removed */
> #endif
>
> + /* Only used with MMC_CAP_DISABLE */
> + int enabled; /* host is enabled */
> + int nesting_cnt; /* "enable" nesting count */
> + int en_dis_recurs; /* detect recursion */
> + unsigned int disable_delay; /* disable delay in msecs */
> + struct delayed_work disable; /* disabling work */
> +
> struct mmc_card *card; /* device attached to this host */
>
> wait_queue_head_t wq;
> @@ -197,5 +234,15 @@ struct regulator;
> int mmc_regulator_get_ocrmask(struct regulator *supply);
> int mmc_regulator_set_ocr(struct regulator *supply, unsigned short vdd_bit);
>
> +int mmc_host_enable(struct mmc_host *host);
> +int mmc_host_disable(struct mmc_host *host);
> +int mmc_host_lazy_disable(struct mmc_host *host);
> +
> +static inline void mmc_set_disable_delay(struct mmc_host *host,
> + unsigned int disable_delay)
> +{
> + host->disable_delay = disable_delay;
> +}
> +
> #endif
>
> --
> 1.5.6.3
>
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