RE: [PATCH v3] mmc: support BKOPS feature for eMMC

["Konstantin Dorfman" <kdorfman@codeaurora.org>]

Hello Jaenhoon,

I have a few suggestions regarding the situation when Host starts BKOPS:

1) Host should start BKOPS (based on BKOPS_STATUS or URGENT_BKOPS event)
when going to mmc_sleep, which means that the bus is in idle state (this
also covers the case in mmc_queue_thread, because in this case no I/O
request exists). It seems like checking the status periodically in addition
to mmc_suspend is not needed. Since if the device was in idle and we
performed a single BKOPS then there is no point in performing another BKOPS
unless there was actually another I/O request.

2) Also this implies an answer to the question about need to interrupt BKOPS
before powering off card - the answer is no.

3) Based on statistical data we have (day long test) it looks like we do not
need to do any preventive BKOPS caused by BKOPS_STATUS less than critical
(0x3).

Thanks,
Konstantin Dorfman
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum

-----Original Message-----
From: linux-mmc-owner@vger.kernel.org
[mailto:linux-mmc-owner@vger.kernel.org] On Behalf Of Jaehoon Chung
Sent: Thursday, November 17, 2011 2:50 AM
To: linux-mmc
Cc: Chris Ball; Kyungmin Park; Hanumath Prasad; Per Forlin; Sebastian
Rasmussen; Dong, Chuanxiao; svenkatr@ti.com
Subject: [PATCH v3] mmc: support BKOPS feature for eMMC

Enable eMMC background operations (BKOPS) feature.

If URGENT_BKOPS is set after a response, note that BKOPS
are required. After all I/O requests are finished, run
BKOPS if required. Should read/write operations be requested
during BKOPS, first issue HPI to interrupt the ongoing BKOPS
and then service the request.

If you want to enable this feature, set MMC_CAP2_BKOPS.

Future considerations
 * Check BKOPS_LEVEL=1 and start BKOPS in a preventive manner.
 * Interrupt ongoing BKOPS before powering off the card.

Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
CC: Hanumath Prasad <hanumath.prasad@stericsson.com>
---
Changelog V3:
	- move the bkops setting's location in mmc_blk_issue_rw_rq
	- modify condition checking
	- bkops_en is assigned ext_csd[EXT_CSD_BKOPS_EN] instead of "1"
	- remove the unused code
	- change pr_debug instead of pr_warn in mmc_send_hpi_cmd
	- Add the Future consideration suggested by Per
	
Changelog V2:
	- Use EXCEPTION_STATUS instead of URGENT_BKOPS
	- Add function to check Exception_status(for eMMC4.5)
	- remove unnecessary code.

 drivers/mmc/card/block.c   |   10 +++++
 drivers/mmc/card/queue.c   |    4 ++
 drivers/mmc/core/core.c    |   87
++++++++++++++++++++++++++++++++++++++++++++
 drivers/mmc/core/mmc.c     |    8 ++++
 drivers/mmc/core/mmc_ops.c |    6 +++-
 include/linux/mmc/card.h   |   12 ++++++
 include/linux/mmc/core.h   |    3 ++
 include/linux/mmc/host.h   |    1 +
 include/linux/mmc/mmc.h    |   14 +++++++
 9 files changed, 144 insertions(+), 1 deletions(-)

diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index c80bb6d..9d19ebb 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -1188,6 +1188,16 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq,
struct request *rqc)
 		type = rq_data_dir(req) == READ ? MMC_BLK_READ :
MMC_BLK_WRITE;
 		mmc_queue_bounce_post(mq_rq);
 
+		/*
+		 * Check BKOPS urgency from each R1 response
+		 */
+		if (mmc_card_mmc(card) &&
+			(brq->cmd.resp[0] & R1_EXCEPTION_EVENT)) {
+			if (mmc_is_exception_event(card,
+					EXT_CSD_URGENT_BKOPS))
+				mmc_card_set_need_bkops(card);
+		}
+
 		switch (status) {
 		case MMC_BLK_SUCCESS:
 		case MMC_BLK_PARTIAL:
diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c
index dcad59c..20bb4a5 100644
--- a/drivers/mmc/card/queue.c
+++ b/drivers/mmc/card/queue.c
@@ -61,6 +61,9 @@ static int mmc_queue_thread(void *d)
 		spin_unlock_irq(q->queue_lock);
 
 		if (req || mq->mqrq_prev->req) {
+			if (mmc_card_doing_bkops(mq->card))
+				mmc_interrupt_bkops(mq->card);
+
 			set_current_state(TASK_RUNNING);
 			mq->issue_fn(mq, req);
 		} else {
@@ -68,6 +71,7 @@ static int mmc_queue_thread(void *d)
 				set_current_state(TASK_RUNNING);
 				break;
 			}
+			mmc_start_bkops(mq->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 7ee2e07..2d2f1d5 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -238,6 +238,50 @@ mmc_start_request(struct mmc_host *host, struct
mmc_request *mrq)
 	host->ops->request(host, mrq);
 }
 
+/**
+ *	mmc_start_bkops - start BKOPS for supported cards
+ *	@card: MMC card to start BKOPS
+ *
+ *	Start background operations whenever requested.
+ *	when the urgent BKOPS bit is set in a R1 command response
+ *	then background operations should be started immediately.
+*/
+void mmc_start_bkops(struct mmc_card *card)
+{
+	int err;
+	unsigned long flags;
+
+	BUG_ON(!card);
+	if ((!card->ext_csd.bkops_en) ||
+			!(card->host->caps2 & MMC_CAP2_BKOPS))
+		return;
+
+	/*
+	 * If card is already doing bkops or need for
+	 * bkops flag is not set, then do nothing just
+	 * return
+	 */
+	if (mmc_card_doing_bkops(card)
+			|| !mmc_card_need_bkops(card))
+		return;
+
+	mmc_claim_host(card->host);
+	err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
+			EXT_CSD_BKOPS_START, 1, 0);
+	if (err) {
+		pr_warning("error %d starting bkops\n", err);
+		mmc_card_clr_need_bkops(card);
+		goto out;
+	}
+	spin_lock_irqsave(&card->host->lock, flags);
+	mmc_card_clr_need_bkops(card);
+	mmc_card_set_doing_bkops(card);
+	spin_unlock_irqrestore(&card->host->lock, flags);
+out:
+	mmc_release_host(card->host);
+}
+EXPORT_SYMBOL(mmc_start_bkops);
+
 static void mmc_wait_done(struct mmc_request *mrq)
 {
 	complete(&mrq->completion);
@@ -466,6 +510,49 @@ int mmc_wait_for_cmd(struct mmc_host *host, struct
mmc_command *cmd, int retries
 EXPORT_SYMBOL(mmc_wait_for_cmd);
 
 /**
+ *	mmc_interrupt_bkops - interrupt ongoing BKOPS
+ *	@card: MMC card to check BKOPS
+ *
+ *	Send HPI command to interrupt ongoing background operations,
+ *	to allow rapid servicing of foreground operations,e.g. read/
+ *	writes. Wait until the card comes out of the programming state
+ *	to avoid errors in servicing read/write requests.
+ */
+int mmc_interrupt_bkops(struct mmc_card *card)
+{
+	int err = 0;
+	unsigned long flags;
+
+	BUG_ON(!card);
+
+	err = mmc_interrupt_hpi(card);
+
+	spin_lock_irqsave(&card->host->lock, flags);
+	mmc_card_clr_doing_bkops(card);
+	spin_unlock_irqrestore(&card->host->lock, flags);
+
+	return err;
+}
+EXPORT_SYMBOL(mmc_interrupt_bkops);
+
+int mmc_is_exception_event(struct mmc_card *card, unsigned int value)
+{
+	int err;
+	u8 ext_csd[512];
+
+	/* In eMMC 4.41, R1_EXCEPTION_EVENT is URGENT_BKOPS */
+	if (card->ext_csd.rev == 5)
+		return 1;
+
+	err = mmc_send_ext_csd(card, ext_csd);
+	if (err)
+		return err;
+
+	return (ext_csd[EXT_CSD_EXCEPTION_STATUS] & value) ? 1 : 0;
+}
+EXPORT_SYMBOL(mmc_is_exception_event);
+
+/**
  *	mmc_set_data_timeout - set the timeout for a data command
  *	@data: data phase for command
  *	@card: the MMC card associated with the data transfer
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index a1223bd..514ad0f 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -448,6 +448,14 @@ static int mmc_read_ext_csd(struct mmc_card *card, u8
*ext_csd)
 	}
 
 	if (card->ext_csd.rev >= 5) {
+		/* check whether the eMMC card support BKOPS */
+		if (ext_csd[EXT_CSD_BKOPS_SUPPORT] & 0x1) {
+			card->ext_csd.bkops = 1;
+			card->ext_csd.bkops_en = ext_csd[EXT_CSD_BKOPS_EN];
+			card->ext_csd.raw_bkops_status =
+				ext_csd[EXT_CSD_BKOPS_STATUS];
+		}
+
 		/* check whether the eMMC card supports HPI */
 		if (ext_csd[EXT_CSD_HPI_FEATURES] & 0x1) {
 			card->ext_csd.hpi = 1;
diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
index 007863e..2e397d5 100644
--- a/drivers/mmc/core/mmc_ops.c
+++ b/drivers/mmc/core/mmc_ops.c
@@ -398,6 +398,10 @@ int mmc_switch(struct mmc_card *card, u8 set, u8 index,
u8 value,
 	if (err)
 		return err;
 
+	/* No need to check card status in case of BKOPS switch*/
+	if (index == EXT_CSD_BKOPS_START)
+		return 0;
+
 	/* Must check status to be sure of no errors */
 	do {
 		err = mmc_send_status(card, &status);
@@ -568,7 +572,7 @@ int mmc_send_hpi_cmd(struct mmc_card *card, u32 *status)
 
 	err = mmc_wait_for_cmd(card->host, &cmd, 0);
 	if (err) {
-		pr_warn("%s: error %d interrupting operation. "
+		pr_debug("%s: error %d interrupting operation. "
 			"HPI command response %#x\n",
mmc_hostname(card->host),
 			err, cmd.resp[0]);
 		return err;
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index 534974c..3c983d7 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -70,6 +70,8 @@ struct mmc_ext_csd {
 	unsigned int		cache_size;		/* Units: KB */
 	bool			hpi_en;			/* HPI enablebit */
 	bool			hpi;			/* HPI support bit
*/
+	bool			bkops;		/* background support bit */
+	bool			bkops_en;	/* background enable bit */
 	unsigned int		hpi_cmd;		/* cmd used as HPI
*/
 	u8			raw_partition_support;	/* 160 */
 	u8			raw_erased_mem_count;	/* 181 */
@@ -84,6 +86,7 @@ struct mmc_ext_csd {
 	u8			raw_sec_erase_mult;	/* 230 */
 	u8			raw_sec_feature_support;/* 231 */
 	u8			raw_trim_mult;		/* 232 */
+	u8			raw_bkops_status;	/* 246 */
 	u8			raw_sectors[4];		/* 212 - 4 bytes */
 
 	unsigned int            feature_support;
@@ -209,6 +212,8 @@ struct mmc_card {
 #define MMC_STATE_HIGHSPEED_DDR (1<<4)		/* card is in high speed
mode */
 #define MMC_STATE_ULTRAHIGHSPEED (1<<5)		/* card is in ultra
high speed mode */
 #define MMC_CARD_SDXC		(1<<6)		/* card is SDXC */
+#define MMC_STATE_NEED_BKOPS	(1<<7)		/* card need to do BKOPS */
+#define MMC_STATE_DOING_BKOPS	(1<<8)		/* card is doing BKOPS */
 	unsigned int		quirks; 	/* card quirks */
 #define MMC_QUIRK_LENIENT_FN0	(1<<0)		/* allow SDIO FN0 writes
outside of the VS CCCR range */
 #define MMC_QUIRK_BLKSZ_FOR_BYTE_MODE (1<<1)	/* use func->cur_blksize */
@@ -370,6 +375,8 @@ static inline void __maybe_unused remove_quirk(struct
mmc_card *card, int data)
 #define mmc_card_uhs(c)		((c)->state &
MMC_STATE_ULTRAHIGHSPEED)
 #define mmc_sd_card_uhs(c)	((c)->state & MMC_STATE_ULTRAHIGHSPEED)
 #define mmc_card_ext_capacity(c) ((c)->state & MMC_CARD_SDXC)
+#define mmc_card_need_bkops(c)	((c)->state & MMC_STATE_NEED_BKOPS)
+#define mmc_card_doing_bkops(c)	((c)->state & MMC_STATE_DOING_BKOPS)
 
 #define mmc_card_set_present(c)	((c)->state |= MMC_STATE_PRESENT)
 #define mmc_card_set_readonly(c) ((c)->state |= MMC_STATE_READONLY)
@@ -379,6 +386,11 @@ static inline void __maybe_unused remove_quirk(struct
mmc_card *card, int data)
 #define mmc_card_set_uhs(c) ((c)->state |= MMC_STATE_ULTRAHIGHSPEED)
 #define mmc_sd_card_set_uhs(c) ((c)->state |= MMC_STATE_ULTRAHIGHSPEED)
 #define mmc_card_set_ext_capacity(c) ((c)->state |= MMC_CARD_SDXC)
+#define mmc_card_set_need_bkops(c)	((c)->state |= MMC_STATE_NEED_BKOPS)
+#define mmc_card_set_doing_bkops(c)	((c)->state |=
MMC_STATE_DOING_BKOPS)
+
+#define mmc_card_clr_need_bkops(c)	((c)->state &=
~MMC_STATE_NEED_BKOPS)
+#define mmc_card_clr_doing_bkops(c)	((c)->state &=
~MMC_STATE_DOING_BKOPS)
 
 /*
  * Quirk add/remove for MMC products.
diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
index 174a844..f6b997a 100644
--- a/include/linux/mmc/core.h
+++ b/include/linux/mmc/core.h
@@ -134,6 +134,8 @@ struct mmc_host;
 struct mmc_card;
 struct mmc_async_req;
 
+extern int mmc_interrupt_bkops(struct mmc_card *);
+extern int mmc_is_exception_event(struct mmc_card *, unsigned int);
 extern struct mmc_async_req *mmc_start_req(struct mmc_host *,
 					   struct mmc_async_req *, int *);
 extern int mmc_interrupt_hpi(struct mmc_card *);
@@ -163,6 +165,7 @@ extern int mmc_can_sanitize(struct mmc_card *card);
 extern int mmc_can_secure_erase_trim(struct mmc_card *card);
 extern int mmc_erase_group_aligned(struct mmc_card *card, unsigned int
from,
 				   unsigned int nr);
+extern void mmc_start_bkops(struct mmc_card *card);
 extern unsigned int mmc_calc_max_discard(struct mmc_card *card);
 
 extern int mmc_set_blocklen(struct mmc_card *card, unsigned int blocklen);
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 706f722..4629e84 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -242,6 +242,7 @@ struct mmc_host {
 #define MMC_CAP2_CACHE_CTRL	(1 << 1)	/* Allow cache control */
 #define MMC_CAP2_POWEROFF_NOTIFY (1 << 2)	/* Notify poweroff supported
*/
 #define MMC_CAP2_NO_MULTI_READ	(1 << 3)	/* Multiblock reads don't
work */
+#define MMC_CAP2_BKOPS		(1 << 4)	/* BKOPS supported */
 
 	mmc_pm_flag_t		pm_caps;	/* supported pm features */
 	unsigned int        power_notify_type;
diff --git a/include/linux/mmc/mmc.h b/include/linux/mmc/mmc.h
index 0e71356..20b1420 100644
--- a/include/linux/mmc/mmc.h
+++ b/include/linux/mmc/mmc.h
@@ -138,6 +138,7 @@ static inline bool mmc_op_multi(u32 opcode)
 #define R1_CURRENT_STATE(x)	((x & 0x00001E00) >> 9)	/* sx, b (4 bits) */
 #define R1_READY_FOR_DATA	(1 << 8)	/* sx, a */
 #define R1_SWITCH_ERROR		(1 << 7)	/* sx, c */
+#define R1_EXCEPTION_EVENT	(1 << 6)	/* sx, a */
 #define R1_APP_CMD		(1 << 5)	/* sr, c */
 
 #define R1_STATE_IDLE	0
@@ -273,11 +274,14 @@ struct _mmc_csd {
 #define EXT_CSD_FLUSH_CACHE		32      /* W */
 #define EXT_CSD_CACHE_CTRL		33      /* R/W */
 #define EXT_CSD_POWER_OFF_NOTIFICATION	34	/* R/W */
+#define EXT_CSD_EXCEPTION_STATUS	54	/* RO */
 #define EXT_CSD_GP_SIZE_MULT		143	/* R/W */
 #define EXT_CSD_PARTITION_ATTRIBUTE	156	/* R/W */
 #define EXT_CSD_PARTITION_SUPPORT	160	/* RO */
 #define EXT_CSD_HPI_MGMT		161	/* R/W */
 #define EXT_CSD_RST_N_FUNCTION		162	/* R/W */
+#define EXT_CSD_BKOPS_EN		163	/* R/W */
+#define EXT_CSD_BKOPS_START		164	/* W */
 #define EXT_CSD_SANITIZE_START		165     /* W */
 #define EXT_CSD_WR_REL_PARAM		166	/* RO */
 #define EXT_CSD_ERASE_GROUP_DEF		175	/* R/W */
@@ -310,9 +314,11 @@ struct _mmc_csd {
 #define EXT_CSD_PWR_CL_200_360		237	/* RO */
 #define EXT_CSD_PWR_CL_DDR_52_195	238	/* RO */
 #define EXT_CSD_PWR_CL_DDR_52_360	239	/* RO */
+#define EXT_CSD_BKOPS_STATUS		246	/* RO */
 #define EXT_CSD_POWER_OFF_LONG_TIME	247	/* RO */
 #define EXT_CSD_GENERIC_CMD6_TIME	248	/* RO */
 #define EXT_CSD_CACHE_SIZE		249	/* RO, 4 bytes */
+#define EXT_CSD_BKOPS_SUPPORT		502	/* RO */
 #define EXT_CSD_HPI_FEATURES		503	/* RO */
 
 /*
@@ -373,4 +379,12 @@ struct _mmc_csd {
 #define MMC_SWITCH_MODE_CLEAR_BITS	0x02	/* Clear bits which are 1 in
value */
 #define MMC_SWITCH_MODE_WRITE_BYTE	0x03	/* Set target to value */
 
+/*
+ * EXCEPTION_EVENT_STATUS field (eMMC4.5)
+ */
+#define EXT_CSD_URGENT_BKOPS		BIT(0)
+#define EXT_CSD_DYNCAP_NEEDED		BIT(1)
+#define EXT_CSD_SYSPOOL_EXHAUSTED	BIT(2)
+#define EXT_CSD_PACKED_FAILURE		BIT(3)
+
 #endif /* LINUX_MMC_MMC_H */
--
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