Date:	Tue, 6 Nov 2012 20:28:54 -0800 (PST)
From:	merez@...eaurora.org
To:	"Jaehoon Chung" <jh80.chung@...sung.com>
Cc:	"Maya Erez" <merez@...eaurora.org>, linux-mmc@...r.kernel.org,
	linux-arm-msm@...r.kernel.org,
	"Jaehoon Chung" <jh80.chung@...sung.com>,
	"open list" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] mmc: core: Add support for idle time BKOPS

Hi Jaehoon,

Any update on this patch review and testing?

Thanks,
Maya
On Mon, October 15, 2012 11:53 pm, Jaehoon Chung wrote:
> Hi Maya,
>
> I'm testing with your patch..but i need to have the more time for testing.
> In now, it looks good to me. Thank you for working the idle bkops.
>
> Best Regards,
> Jaehoon Chung
>
>> ---
>> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
>> index 172a768..ed040d5 100644
>> --- a/drivers/mmc/card/block.c
>> +++ b/drivers/mmc/card/block.c
>> @@ -827,6 +827,9 @@ static int mmc_blk_issue_discard_rq(struct mmc_queue
>> *mq, struct request *req)
>>  	from = blk_rq_pos(req);
>>  	nr = blk_rq_sectors(req);
>>
>> +	if (card->ext_csd.bkops_en)
>> +		card->bkops_info.sectors_changed += blk_rq_sectors(req);
> using nr?
>> +
>>  	if (mmc_can_discard(card))
>>  		arg = MMC_DISCARD_ARG;
>>  	else if (mmc_can_trim(card))
>> @@ -1268,6 +1271,9 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue
>> *mq, struct request *rqc)
>>  	if (!rqc && !mq->mqrq_prev->req)
>>  		return 0;
>>
>> +	if (rqc && (card->ext_csd.bkops_en) && (rq_data_dir(rqc) == WRITE))
>> +			card->bkops_info.sectors_changed += blk_rq_sectors(rqc);
> Fix the indent.
>> +
>>  	do {
>>  		if (rqc) {
>>  			/*
>> diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c
>> index e360a97..e96f5cf 100644
>> --- a/drivers/mmc/card/queue.c
>> +++ b/drivers/mmc/card/queue.c
>> @@ -51,6 +51,7 @@ static int mmc_queue_thread(void *d)
>>  {
>>  	struct mmc_queue *mq = d;
>>  	struct request_queue *q = mq->queue;
>> +	struct mmc_card *card = mq->card;
>>
>>  	current->flags |= PF_MEMALLOC;
>>
>> @@ -66,6 +67,17 @@ static int mmc_queue_thread(void *d)
>>  		spin_unlock_irq(q->queue_lock);
>>
>>  		if (req || mq->mqrq_prev->req) {
>> +			/*
>> +			 * If this is the first request, BKOPs might be in
>> +			 * progress and needs to be stopped before issuing the
>> +			 * request
>> +			 */
>> +			if (card->ext_csd.bkops_en &&
>> +			    card->bkops_info.started_delayed_bkops) {
>> +				card->bkops_info.started_delayed_bkops = false;
>> +				mmc_stop_bkops(card);
> if mmc_stop_bkops is failed..?
>> +			}
>> +
>>  			set_current_state(TASK_RUNNING);
>>  			mq->issue_fn(mq, req);
>>  		} else {
>> @@ -73,6 +85,7 @@ static int mmc_queue_thread(void *d)
>>  				set_current_state(TASK_RUNNING);
>>  				break;
>>  			}
>> +			mmc_start_delayed_bkops(card);
>>  			up(&mq->thread_sem);
>>  			schedule();
>>  			down(&mq->thread_sem);
>> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
>> index 6612163..fd8783d 100644
>> --- a/drivers/mmc/core/core.c
>> +++ b/drivers/mmc/core/core.c
>> @@ -253,9 +253,42 @@ mmc_start_request(struct mmc_host *host, struct
>> mmc_request *mrq)
>>  }
>>
>>  /**
>> + * mmc_start_delayed_bkops() - Start a delayed work to check for
>> + *      the need of non urgent BKOPS
>> + *
>> + * @card: MMC card to start BKOPS on
>> + */
>> +void mmc_start_delayed_bkops(struct mmc_card *card)
>> +{
>> +	if (!card || !card->ext_csd.bkops_en || mmc_card_doing_bkops(card))
>> +		return;
>> +
>> +	if (card->bkops_info.sectors_changed <
>> +	    BKOPS_MIN_SECTORS_TO_QUEUE_DELAYED_WORK)
>> +		return;
>> +
>> +	pr_debug("%s: %s: queueing delayed_bkops_work\n",
>> +		 mmc_hostname(card->host), __func__);
>> +
>> +	card->bkops_info.sectors_changed = 0;
>> +
>> +	/*
>> +	 * cancel_delayed_bkops_work will prevent a race condition between
>> +	 * fetching a request by the mmcqd and the delayed work, in case
>> +	 * it was removed from the queue work but not started yet
>> +	 */
>> +	card->bkops_info.cancel_delayed_work = false;
>> +	card->bkops_info.started_delayed_bkops = true;
>> +	queue_delayed_work(system_nrt_wq, &card->bkops_info.dw,
>> +			   msecs_to_jiffies(
>> +				   card->bkops_info.delay_ms));
>> +}
>> +EXPORT_SYMBOL(mmc_start_delayed_bkops);
>> +
>> +/**
>>   *	mmc_start_bkops - start BKOPS for supported cards
>>   *	@card: MMC card to start BKOPS
>> - *	@form_exception: A flag to indicate if this function was
>> + *	@from_exception: A flag to indicate if this function was
>>   *			 called due to an exception raised by the card
>>   *
>>   *	Start background operations whenever requested.
>> @@ -269,25 +302,47 @@ void mmc_start_bkops(struct mmc_card *card, bool
>> from_exception)
>>  	bool use_busy_signal;
>>
>>  	BUG_ON(!card);
>> -
>> -	if (!card->ext_csd.bkops_en || mmc_card_doing_bkops(card))
>> +	if (!card->ext_csd.bkops_en)
>>  		return;
>>
>> +	mmc_claim_host(card->host);
>> +
>> +	if ((card->bkops_info.cancel_delayed_work) && !from_exception) {
>> +		pr_debug("%s: %s: cancel_delayed_work was set, exit\n",
>> +			 mmc_hostname(card->host), __func__);
>> +		card->bkops_info.cancel_delayed_work = false;
>> +		goto out;
>> +	}
>> +
>> +	if (mmc_card_doing_bkops(card)) {
>> +		pr_debug("%s: %s: already doing bkops, exit\n",
>> +			 mmc_hostname(card->host), __func__);
>> +		goto out;
>> +	}
>> +
>>  	err = mmc_read_bkops_status(card);
>>  	if (err) {
>>  		pr_err("%s: Failed to read bkops status: %d\n",
>>  		       mmc_hostname(card->host), err);
>> -		return;
>> +		goto out;
>>  	}
>>
>>  	if (!card->ext_csd.raw_bkops_status)
>> -		return;
>> +		goto out;
>> +
>> +	pr_info("%s: %s: card->ext_csd.raw_bkops_status = 0x%x\n",
>> +		mmc_hostname(card->host), __func__,
>> +		card->ext_csd.raw_bkops_status);
>>
>> +	/*
>> +	 * If the function was called due to exception but there is no need
>> +	 * for urgent BKOPS, BKOPs will be performed by the delayed BKOPs
>> +	 * work, before going to suspend
>> +	 */
>>  	if (card->ext_csd.raw_bkops_status < EXT_CSD_BKOPS_LEVEL_2 &&
>>  	    from_exception)
>> -		return;
>> +		goto out;
>>
>> -	mmc_claim_host(card->host);
>>  	if (card->ext_csd.raw_bkops_status >= EXT_CSD_BKOPS_LEVEL_2) {
>>  		timeout = MMC_BKOPS_MAX_TIMEOUT;
>>  		use_busy_signal = true;
>> @@ -309,13 +364,108 @@ void mmc_start_bkops(struct mmc_card *card, bool
>> from_exception)
>>  	 * bkops executed synchronously, otherwise
>>  	 * the operation is in progress
>>  	 */
>> -	if (!use_busy_signal)
>> +	if (!use_busy_signal) {
>>  		mmc_card_set_doing_bkops(card);
>> +		pr_debug("%s: %s: starting the polling thread\n",
>> +			 mmc_hostname(card->host), __func__);
>> +		queue_work(system_nrt_wq,
>> +			   &card->bkops_info.poll_for_completion);
>> +	}
>> +
>>  out:
>>  	mmc_release_host(card->host);
>>  }
>>  EXPORT_SYMBOL(mmc_start_bkops);
>>
>> +/**
>> + * mmc_bkops_completion_polling() - Poll on the card status to
>> + * wait for the non-blocking BKOPS completion
>> + * @work:	The completion polling work
>> + *
>> + * The on-going reading of the card status will prevent the card
>> + * from getting into suspend while it is in the middle of
>> + * performing BKOPS.
>> + * Since the non blocking BKOPS can be interrupted by a fetched
>> + * request we also check IF mmc_card_doing_bkops in each
>> + * iteration.
>> + */
>> +void mmc_bkops_completion_polling(struct work_struct *work)
>> +{
>> +	struct mmc_card *card = container_of(work, struct mmc_card,
>> +			bkops_info.poll_for_completion);
>> +	unsigned long timeout_jiffies = jiffies +
>> +		msecs_to_jiffies(BKOPS_COMPLETION_POLLING_TIMEOUT_MS);
>> +	u32 status;
>> +	int err;
>> +
>> +	/*
>> +	 * Wait for the BKOPs to complete. Keep reading the status to prevent
>> +	 * the host from getting into suspend
>> +	 */
>> +	do {
>> +		mmc_claim_host(card->host);
>> +
>> +		if (!mmc_card_doing_bkops(card))
>> +			goto out;
>> +
>> +		err = mmc_send_status(card, &status);
>> +		if (err) {
>> +			pr_err("%s: error %d requesting status\n",
>> +			       mmc_hostname(card->host), err);
>> +			goto out;
>> +		}
>> +
>> +		/*
>> +		 * Some cards mishandle the status bits, so make sure to check
>> +		 * both the busy indication and the card state.
>> +		 */
>> +		if ((status & R1_READY_FOR_DATA) &&
>> +		    (R1_CURRENT_STATE(status) != R1_STATE_PRG)) {
>> +			pr_debug("%s: %s: completed BKOPs, exit polling\n",
>> +				 mmc_hostname(card->host), __func__);
>> +			mmc_card_clr_doing_bkops(card);
>> +			card->bkops_info.started_delayed_bkops = false;
>> +			goto out;
>> +		}
>> +
>> +		mmc_release_host(card->host);
>> +
>> +		/*
>> +		 * Sleep before checking the card status again to allow the
>> +		 * card to complete the BKOPs operation
>> +		 */
>> +		msleep(BKOPS_COMPLETION_POLLING_INTERVAL_MS);
>> +	} while (time_before(jiffies, timeout_jiffies));
>> +
>> +	pr_err("%s: %s: exit polling due to timeout\n",
>> +	       mmc_hostname(card->host), __func__);
>> +
>> +	return;
>> +out:
>> +	mmc_release_host(card->host);
>> +}
>> +
>> +/**
>> + * mmc_start_idle_time_bkops() - check if a non urgent BKOPS is
>> + * needed
>> + * @work:	The idle time BKOPS work
>> + */
>> +void mmc_start_idle_time_bkops(struct work_struct *work)
>> +{
>> +	struct mmc_card *card = container_of(work, struct mmc_card,
>> +			bkops_info.dw.work);
>> +
>> +	/*
>> +	 * Prevent a race condition between mmc_stop_bkops and the delayed
>> +	 * BKOPS work in case the delayed work is executed on another CPU
>> +	 */
>> +	if (card->bkops_info.cancel_delayed_work)
>> +		return;
>> +
>> +	mmc_start_bkops(card, false);
>> +}
>> +EXPORT_SYMBOL(mmc_start_idle_time_bkops);
>> +
>>  static void mmc_wait_done(struct mmc_request *mrq)
>>  {
>>  	complete(&mrq->completion);
>> @@ -582,6 +732,19 @@ int mmc_stop_bkops(struct mmc_card *card)
>>  	int err = 0;
>>
>>  	BUG_ON(!card);
>> +
>> +	mmc_claim_host(card->host);
>> +
>> +	/*
>> +	 * Notify the delayed work to be cancelled, in case it was already
>> +	 * removed from the queue, but was not started yet
>> +	 */
>> +	card->bkops_info.cancel_delayed_work = true;
>> +	if (delayed_work_pending(&card->bkops_info.dw))
>> +		cancel_delayed_work_sync(&card->bkops_info.dw);
>> +	if (!mmc_card_doing_bkops(card))
>> +		goto out;
>> +
>>  	err = mmc_interrupt_hpi(card);
>>
>>  	/*
>> @@ -593,6 +756,8 @@ int mmc_stop_bkops(struct mmc_card *card)
>>  		err = 0;
>>  	}
>>
>> +out:
>> +	mmc_release_host(card->host);
>>  	return err;
>>  }
>>  EXPORT_SYMBOL(mmc_stop_bkops);
>> @@ -2566,15 +2731,13 @@ int mmc_pm_notify(struct notifier_block
>> *notify_block,
>>  	switch (mode) {
>>  	case PM_HIBERNATION_PREPARE:
>>  	case PM_SUSPEND_PREPARE:
>> -		if (host->card && mmc_card_mmc(host->card) &&
>> -		    mmc_card_doing_bkops(host->card)) {
>> +		if (host->card && mmc_card_mmc(host->card)) {
>>  			err = mmc_stop_bkops(host->card);
>>  			if (err) {
>>  				pr_err("%s: didn't stop bkops\n",
>>  					mmc_hostname(host));
>>  				return err;
>>  			}
>> -			mmc_card_clr_doing_bkops(host->card);
>>  		}
>>
>>  		spin_lock_irqsave(&host->lock, flags);
>> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
>> index 7509de1..f8ff640 100644
>> --- a/drivers/mmc/core/mmc.c
>> +++ b/drivers/mmc/core/mmc.c
>> @@ -1258,6 +1258,30 @@ static int mmc_init_card(struct mmc_host *host,
>> u32 ocr,
>>  		}
>>  	}
>>
>> +	if (!oldcard) {
>> +		if (card->ext_csd.bkops_en) {
>> +			INIT_DELAYED_WORK(&card->bkops_info.dw,
>> +					  mmc_start_idle_time_bkops);
>> +			INIT_WORK(&card->bkops_info.poll_for_completion,
>> +				  mmc_bkops_completion_polling);
>> +
>> +			/*
>> +			 * Calculate the time to start the BKOPs checking.
>> +			 * The idle time of the host controller should be taken
>> +			 * into account in order to prevent a race condition
>> +			 * before starting BKOPs and going into suspend.
>> +			 * If the host controller didn't set its idle time,
>> +			 * a default value is used.
>> +			 */
>> +			card->bkops_info.delay_ms = MMC_IDLE_BKOPS_TIME_MS;
>> +			if (card->bkops_info.host_suspend_tout_ms)
>> +				card->bkops_info.delay_ms = min(
>> +					card->bkops_info.delay_ms,
>> +				      card->bkops_info.host_suspend_tout_ms/2);
>> +
>> +		}
>> +	}
>> +
>>  	if (!oldcard)
>>  		host->card = card;
>>
>> diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
>> index 78cc3be..0e4d55a 100644
>> --- a/include/linux/mmc/card.h
>> +++ b/include/linux/mmc/card.h
>> @@ -207,6 +207,48 @@ struct mmc_part {
>>  #define MMC_BLK_DATA_AREA_GP	(1<<2)
>>  };
>>
>> +/**
>> + * struct mmc_bkops_info - BKOPS data
>> + * @dw:	Idle time bkops delayed work
>> + * @host_suspend_tout_ms:	The host controller idle time,
>> + * before getting into suspend
>> + * @delay_ms:	The time to start the BKOPS
>> + *        delayed work once MMC thread is idle
>> + * @poll_for_completion:	Poll on BKOPS completion
>> + * @cancel_delayed_work: A flag to indicate if the delayed work
>> + *        should be cancelled
>> + * @started_delayed_bkops:  A flag to indicate if the delayed
>> + *        work was scheduled
>> + * @sectors_changed:  number of  sectors written or
>> + *       discard since the last idle BKOPS were scheduled
>> + */
>> +struct mmc_bkops_info {
>> +	struct delayed_work	dw;
>> +	unsigned int		host_suspend_tout_ms;
>> +	unsigned int		delay_ms;
>> +/*
>> + * A default time for checking the need for non urgent BKOPS once mmcqd
>> + * is idle.
>> + */
>> +#define MMC_IDLE_BKOPS_TIME_MS 2000
>> +	struct work_struct	poll_for_completion;
>> +/* Polling timeout and interval for waiting on non-blocking BKOPs
>> completion */
>> +#define BKOPS_COMPLETION_POLLING_TIMEOUT_MS 10000 /* in ms */
>> +#define BKOPS_COMPLETION_POLLING_INTERVAL_MS 1000 /* in ms */
>> +	bool			cancel_delayed_work;
>> +	bool			started_delayed_bkops;
>> +	unsigned int		sectors_changed;
>> +/*
>> + * Since canceling the delayed work might have significant effect on
>> the
>> + * performance of small requests we won't queue the delayed work every
>> time
>> + * mmcqd thread is idle.
>> + * The delayed work for idle BKOPS will be scheduled only after a
>> significant
>> + * amount of write or discard data.
>> + * 100MB is chosen based on benchmark tests.
>> + */
>> +#define BKOPS_MIN_SECTORS_TO_QUEUE_DELAYED_WORK 204800 /* 100MB */
>> +};
>> +
>>  /*
>>   * MMC device
>>   */
>> @@ -281,6 +323,8 @@ struct mmc_card {
>>  	struct dentry		*debugfs_root;
>>  	struct mmc_part	part[MMC_NUM_PHY_PARTITION]; /* physical partitions */
>>  	unsigned int    nr_parts;
>> +
>> +	struct mmc_bkops_info	bkops_info;
>>  };
>>
>>  /*
>> diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
>> index 9b9cdaf..665d345 100644
>> --- a/include/linux/mmc/core.h
>> +++ b/include/linux/mmc/core.h
>> @@ -145,6 +145,9 @@ extern int mmc_app_cmd(struct mmc_host *, struct
>> mmc_card *);
>>  extern int mmc_wait_for_app_cmd(struct mmc_host *, struct mmc_card *,
>>  	struct mmc_command *, int);
>>  extern void mmc_start_bkops(struct mmc_card *card, bool
>> from_exception);
>> +extern void mmc_start_delayed_bkops(struct mmc_card *card);
>> +extern void mmc_start_idle_time_bkops(struct work_struct *work);
>> +extern void mmc_bkops_completion_polling(struct work_struct *work);
>>  extern int __mmc_switch(struct mmc_card *, u8, u8, u8, unsigned int,
>> bool);
>>  extern int mmc_switch(struct mmc_card *, u8, u8, u8, unsigned int);
>>
>>
>
>


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