Re: [RESEND PATCH v12] mmc: support BKOPS feature for eMMC

[Chris Ball <cjb@laptop.org>]

Hi Jaehoon,

On Mon, Sep 17 2012, Jaehoon Chung wrote:
> Enable eMMC background operations (BKOPS) feature.
>
> If URGENT_BKOPS is set after a response, note that BKOPS
> are required. Immediately run BKOPS if required.
> read/write operations should be requested during BKOPS(LEVEL-1),
> then issue HPI to interrupt the ongoing BKOPS 
> and service the foreground operation.
> (This patch is only control the LEVEL2/3.)
>
> When repeating the writing 1GB data, at a certain time, performance is decreased.
> At that time, card is also triggered the Level-3 or Level-2.
> After running bkops, performance is recovered.
>
> Future considerations
>  * Check BKOPS_LEVEL=1 and start BKOPS in a preventive manner.
>  * Interrupt ongoing BKOPS before powering off the card.
>  * How get BKOPS_STATUS value.(periodically send ext_csd command?)
>  * If use periodic bkops, also consider runtime_pm control.
>
> Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
> Signed-off-by: Konstantin Dorfman <kdorfman@codeaurora.org>
> Reviewed-by: Maya Erez <merez@codeaurora.org>

Thanks, looks good now.  Is it okay if I apply this stylistic patch
before pushing to mmc-next?


diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 4749557..044cd01 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -43,8 +43,8 @@
 #include "sdio_ops.h"
 
 /*
- * The Background operation can take a long time, depends on the house keeping
- * operations the card has to peform
+ * Background operations can take a long time, depending on the housekeeping
+ * operations the card has to perform.
  */
 #define MMC_BKOPS_MAX_TIMEOUT	(4 * 60 * 1000) /* max time to wait in ms */
 
@@ -255,11 +255,11 @@ mmc_start_request(struct mmc_host *host, struct mmc_request *mrq)
 /**
  *	mmc_start_bkops - start BKOPS for supported cards
  *	@card: MMC card to start BKOPS
- *	@form_exception: A flags to indicate if this function was
- *			called due to an exception raised by the card
+ *	@form_exception: A flag to indicate if this function was
+ *			 called due to an exception raised by the card
  *
  *	Start background operations whenever requested.
- *	when the urgent BKOPS bit is set in a R1 command response
+ *	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, bool from_exception)
@@ -275,7 +275,7 @@ void mmc_start_bkops(struct mmc_card *card, bool from_exception)
 
 	err = mmc_read_bkops_status(card);
 	if (err) {
-		pr_err("%s: Didn't read bkops status : %d\n",
+		pr_err("%s: Failed to read bkops status: %d\n",
 		       mmc_hostname(card->host), err);
 		return;
 	}
@@ -283,8 +283,8 @@ void mmc_start_bkops(struct mmc_card *card, bool from_exception)
 	if (!card->ext_csd.raw_bkops_status)
 		return;
 
-	if (card->ext_csd.raw_bkops_status < EXT_CSD_BKOPS_LEVEL_2
-	    && (from_exception))
+	if (card->ext_csd.raw_bkops_status < EXT_CSD_BKOPS_LEVEL_2 &&
+	    from_exception)
 		return;
 
 	mmc_claim_host(card->host);
@@ -299,8 +299,8 @@ void mmc_start_bkops(struct mmc_card *card, bool from_exception)
 	err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
 			EXT_CSD_BKOPS_START, 1, timeout, use_busy_signal);
 	if (err) {
-		pr_warn("%s: error %d starting bkops\n",
-			   mmc_hostname(card->host), err);
+		pr_warn("%s: Error %d starting bkops\n",
+			mmc_hostname(card->host), err);
 		goto out;
 	}
 
@@ -429,9 +429,9 @@ struct mmc_async_req *mmc_start_req(struct mmc_host *host,
 		 * Check BKOPS urgency for each R1 response
 		 */
 		if (host->card && mmc_card_mmc(host->card) &&
-		((mmc_resp_type(host->areq->mrq->cmd) == MMC_RSP_R1) ||
-		 (mmc_resp_type(host->areq->mrq->cmd) == MMC_RSP_R1B)) &&
-		(host->areq->mrq->cmd->resp[0] & R1_EXCEPTION_EVENT))
+		    ((mmc_resp_type(host->areq->mrq->cmd) == MMC_RSP_R1) ||
+		     (mmc_resp_type(host->areq->mrq->cmd) == MMC_RSP_R1B)) &&
+		    (host->areq->mrq->cmd->resp[0] & R1_EXCEPTION_EVENT))
 			mmc_start_bkops(host->card, true);
 	}
 
@@ -477,7 +477,7 @@ EXPORT_SYMBOL(mmc_wait_for_req);
  *	@card: the MMC card associated with the HPI transfer
  *
  *	Issued High Priority Interrupt, and check for card status
- *	util out-of prg-state.
+ *	until out-of prg-state.
  */
 int mmc_interrupt_hpi(struct mmc_card *card)
 {
@@ -572,8 +572,8 @@ EXPORT_SYMBOL(mmc_wait_for_cmd);
  *	mmc_stop_bkops - stop ongoing BKOPS
  *	@card: MMC card to check BKOPS
  *
- *	Send HPI command to stop ongoing background operations,
- *	to allow rapid servicing of foreground operations,e.g. read/
+ *	Send HPI command to stop 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.
  */
@@ -585,8 +585,8 @@ int mmc_stop_bkops(struct mmc_card *card)
 	err = mmc_interrupt_hpi(card);
 
 	/*
-	 * if err is EINVAL, it's status that can't issue HPI.
-	 * it should complete the BKOPS.
+	 * If err is EINVAL, we can't issue an HPI.
+	 * It should complete the BKOPS.
 	 */
 	if (!err || (err == -EINVAL)) {
 		mmc_card_clr_doing_bkops(card);
@@ -603,12 +603,12 @@ int mmc_read_bkops_status(struct mmc_card *card)
 	u8 *ext_csd;
 
 	/*
-	 * In future work, we should be consider storing the entire ext_csd.
+	 * In future work, we should consider storing the entire ext_csd.
 	 */
 	ext_csd = kmalloc(512, GFP_KERNEL);
 	if (!ext_csd) {
-		pr_err("%s: could not allocate a buffer to "
-			"receive the ext_csd.\n", mmc_hostname(card->host));
+		pr_err("%s: could not allocate buffer to receive the ext_csd.\n",
+		       mmc_hostname(card->host));
 		return -ENOMEM;
 	}
 
@@ -2470,15 +2470,14 @@ int mmc_suspend_host(struct mmc_host *host)
 
 	mmc_bus_get(host);
 	if (host->bus_ops && !host->bus_dead) {
-
 		if (host->bus_ops->suspend) {
 			if (mmc_card_doing_bkops(host->card)) {
 				err = mmc_stop_bkops(host->card);
 				if (err)
 					goto out;
 			}
-		}
 			err = host->bus_ops->suspend(host);
+		}
 
 		if (err == -ENOSYS || !host->bus_ops->resume) {
 			/*
@@ -2566,10 +2565,10 @@ int mmc_pm_notify(struct notifier_block *notify_block,
 	case PM_HIBERNATION_PREPARE:
 	case PM_SUSPEND_PREPARE:
 		if (host->card && mmc_card_mmc(host->card) &&
-				mmc_card_doing_bkops(host->card)) {
+		    mmc_card_doing_bkops(host->card)) {
 			err = mmc_stop_bkops(host->card);
 			if (err) {
-				pr_err("%s didn't stop bkops\n",
+				pr_err("%s: didn't stop bkops\n",
 					mmc_hostname(host));
 				return err;
 			}
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 9c5caa6..7509de1 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -463,15 +463,15 @@ 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 */
+		/* check whether the eMMC card supports 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];
 			if (!card->ext_csd.bkops_en)
-				pr_info("%s: Didn't set BKOPS_EN bit!\n",
-						mmc_hostname(card->host));
+				pr_info("%s: BKOPS_EN bit is not set\n",
+					mmc_hostname(card->host));
 		}
 
 		/* check whether the eMMC card supports HPI */

-- 
Chris Ball   <cjb@laptop.org>   <http://printf.net/>
One Laptop Per Child