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Commit 8e19c8cb authored by Adrian Hunter's avatar Adrian Hunter Committed by Veerabhadrarao Badiganti
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mmc: host: Add facility to support re-tuning 



Currently, there is core support for tuning during
initialization. There can also be a need to re-tune
periodically (e.g. sdhci) or to re-tune after the
host controller is powered off (e.g. after PM
runtime suspend / resume) or to re-tune in response
to CRC errors.

The main requirements for re-tuning are:
  - ability to enable / disable re-tuning
  - ability to flag that re-tuning is needed
  - ability to re-tune before any request
  - ability to hold off re-tuning if the card is busy
  - ability to hold off re-tuning if re-tuning is in
  progress
  - ability to run a re-tuning timer

To support those requirements 7 members are added to struct
mmc_host:

  unsigned int		can_retune:1;	/* re-tuning can be used */
  unsigned int		doing_retune:1;	/* re-tuning in progress */
  unsigned int		retune_now:1;   /* do re-tuning at next req */
  int			need_retune;	/* re-tuning is needed */
  int			hold_retune;	/* hold off re-tuning */
  unsigned int		retune_period;  /* re-tuning period in secs */
  struct timer_list	retune_timer;	/* for periodic re-tuning */

need_retune is an integer so it can be set without needing
synchronization. hold_retune is a integer to allow nesting.

Various simple functions are provided to set / clear those
variables.

Subsequent patches take those functions into use.

Signed-off-by: default avatarAdrian Hunter <adrian.hunter@intel.com>
Signed-off-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
Git-commit: dfa13ebbe3340e538b988f5608efd9ff2ca7fc35
Git-repo: git://git.linaro.org/people/ulf.hansson/mmc.git


Change-Id: I82fa292b96ee57f18dd089287940aaca5286a304
Signed-off-by: default avatarVeerabhadrarao Badiganti <vbadigan@codeaurora.org>
parent 4654d9ee

drivers/mmc/core/host.c

+68 −0
Original line number Diff line number Diff line
@@ -312,6 +312,73 @@ static inline void mmc_host_clk_sysfs_init(struct mmc_host *host) 


#endif



void mmc_retune_enable(struct mmc_host *host)

{

	host->can_retune = 1;

	if (host->retune_period)

		mod_timer(&host->retune_timer,

			  jiffies + host->retune_period * HZ);

}



void mmc_retune_disable(struct mmc_host *host)

{

	host->can_retune = 0;

	del_timer_sync(&host->retune_timer);

	host->retune_now = 0;

	host->need_retune = 0;

}



void mmc_retune_timer_stop(struct mmc_host *host)

{

	del_timer_sync(&host->retune_timer);

}

EXPORT_SYMBOL(mmc_retune_timer_stop);



void mmc_retune_hold(struct mmc_host *host)

{

	if (!host->hold_retune)

		host->retune_now = 1;

	host->hold_retune += 1;

}



void mmc_retune_release(struct mmc_host *host)

{

	if (host->hold_retune)

		host->hold_retune -= 1;

	else

		WARN_ON(1);

}



int mmc_retune(struct mmc_host *host)

{

	int err;



	if (host->retune_now)

		host->retune_now = 0;

	else

		return 0;



	if (!host->need_retune || host->doing_retune || !host->card)

		return 0;



	host->need_retune = 0;



	host->doing_retune = 1;



	err = mmc_execute_tuning(host->card);



	host->doing_retune = 0;



	return err;

}



static void mmc_retune_timer(unsigned long data)

{

	struct mmc_host *host = (struct mmc_host *)data;



	mmc_retune_needed(host);

}



/**

 *	mmc_of_parse() - parse host's device-tree node

 *	@host: host whose node should be parsed.
@@ -527,6 +594,7 @@ struct mmc_host *mmc_alloc_host(int extra, struct device *dev) 
#ifdef CONFIG_PM

	host->pm_notify.notifier_call = mmc_pm_notify;

#endif

	setup_timer(&host->retune_timer, mmc_retune_timer, (unsigned long)host);



	/*

	 * By default, hosts do not support SGIO or large requests.

drivers/mmc/core/host.h

+6 −0
Original line number Diff line number Diff line
@@ -15,5 +15,11 @@ 
int mmc_register_host_class(void);

void mmc_unregister_host_class(void);



void mmc_retune_enable(struct mmc_host *host);

void mmc_retune_disable(struct mmc_host *host);

void mmc_retune_hold(struct mmc_host *host);

void mmc_retune_release(struct mmc_host *host);

int mmc_retune(struct mmc_host *host);



#endif

include/linux/mmc/host.h

+23 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 


#include <linux/leds.h>

#include <linux/mutex.h>

#include <linux/timer.h>

#include <linux/sched.h>

#include <linux/device.h>

#include <linux/devfreq.h>
@@ -519,10 +520,18 @@ struct mmc_host { 
#ifdef CONFIG_MMC_DEBUG

	unsigned int		removed:1;	/* host is being removed */

#endif

	unsigned int		can_retune:1;	/* re-tuning can be used */

	unsigned int		doing_retune:1;	/* re-tuning in progress */

	unsigned int		retune_now:1;	/* do re-tuning at next req */



	int			rescan_disable;	/* disable card detection */

	int			rescan_entered;	/* used with nonremovable devices */



	int			need_retune;	/* re-tuning is needed */

	int			hold_retune;	/* hold off re-tuning */

	unsigned int		retune_period;	/* re-tuning period in secs */

	struct timer_list	retune_timer;	/* for periodic re-tuning */



	bool			trigger_card_event; /* card_event necessary */



	struct mmc_card		*card;		/* device attached to this host */
@@ -823,4 +832,18 @@ static inline bool mmc_card_hs400(struct mmc_card *card) 
	return card->host->ios.timing == MMC_TIMING_MMC_HS400;

}



void mmc_retune_timer_stop(struct mmc_host *host);



static inline void mmc_retune_needed(struct mmc_host *host)

{

	if (host->can_retune)

		host->need_retune = 1;

}



static inline void mmc_retune_recheck(struct mmc_host *host)

{

	if (host->hold_retune <= 1)

		host->retune_now = 1;

}



#endif /* LINUX_MMC_HOST_H */