Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 5f2cd81f authored by Yi Sun's avatar Yi Sun Committed by Venkat Gopalakrishnan
Browse files

mmc: enable Enhance Strobe for HS400 



Enhance Strobe is defined in v5.1 eMMC spec. This commit
is to implement it.

Normal Strobe signal for HS400 is only provided during
Data Out and CRC Response. While Enhance Strobe is enabled,
Strobe signal is provided during Data Out, CRC Response and
CMD Response.

While enabling Enhance Strobe, the initialization of HS400
does not need enabling HS200 and executing tuning anymore.
This simplifies the HS400 initialization process much.

Per spec, there is a STROBE_SUPPORT added in EXT_CSD register
to indicate that card supports Enhance Strobe or not. If it is
supported, host can enable this feature by enabling the most
significant bit of BUS_WIDTH before set HS_TIMING to HS400.

Change-Id: I1003352cb31dfaec01fde352da7b879a13c94b3f
Signed-off-by: default avatarYi Sun <yi.y.sun@intel.com>
[venkatg@codeaurora.org: Fix minor conflicts & compilation failure]
Patch-mainline: linux-mmc @ 06/04/15, 19:50
Signed-off-by: default avatarVenkat Gopalakrishnan <venkatg@codeaurora.org>
parent 4c47f344

drivers/mmc/core/mmc.c

+57 −5
Original line number Diff line number Diff line
@@ -648,6 +648,11 @@ static int mmc_read_ext_csd(struct mmc_card *card, u8 *ext_csd) 
	}



	if (card->ext_csd.rev >= 7) {

		/* Enhance Strobe is supported since v5.1 which rev should be

		 * 8 but some eMMC devices can support it with rev 7. So handle

		 * Enhance Strobe here.

		 */

		card->ext_csd.strobe_support = ext_csd[EXT_CSD_STROBE_SUPPORT];

		card->ext_csd.cmdq_support = ext_csd[EXT_CSD_CMDQ_SUPPORT];

		if (card->ext_csd.cmdq_support) {

			/*
@@ -1086,13 +1091,33 @@ static int mmc_select_hs400(struct mmc_card *card) 
{

	struct mmc_host *host = card->host;

	int err = 0;

	u8 val;



	/*

	 * HS400 mode requires 8-bit bus width

	 */

	if (card->ext_csd.strobe_support) {

		if (!(card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400 &&

		    host->caps & MMC_CAP_8_BIT_DATA))

			return 0;



		/* For Enhance Strobe flow. For non Enhance Strobe, signal

		 * voltage will not be set.

		 */

		if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200_1_2V)

			err = __mmc_set_signal_voltage(host,

					MMC_SIGNAL_VOLTAGE_120);



		if (err && card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200_1_8V)

			err = __mmc_set_signal_voltage(host,

					MMC_SIGNAL_VOLTAGE_180);

		if (err)

			return err;

	} else {

		if (!(card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400 &&

		    host->ios.bus_width == MMC_BUS_WIDTH_8))

			return 0;

	}



	/*

	 * Before switching to dual data rate operation for HS400,
@@ -1111,9 +1136,12 @@ static int mmc_select_hs400(struct mmc_card *card) 
		return err;

	}



	val = EXT_CSD_DDR_BUS_WIDTH_8;

	if (card->ext_csd.strobe_support)

		val |= EXT_CSD_BUS_WIDTH_STROBE;

	err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,

			 EXT_CSD_BUS_WIDTH,

			 EXT_CSD_DDR_BUS_WIDTH_8,

			 val,

			 card->ext_csd.generic_cmd6_time);

	if (err) {

		pr_warn("%s: switch to bus width for hs400 failed, err:%d\n",
@@ -1121,6 +1149,25 @@ static int mmc_select_hs400(struct mmc_card *card) 
		return err;

	}



	if (card->ext_csd.strobe_support) {

		mmc_set_bus_width(host, MMC_BUS_WIDTH_8);

		/*

		 * If controller can't handle bus width test,

		 * compare ext_csd previously read in 1 bit mode

		 * against ext_csd at new bus width

		 */

		if (!(host->caps & MMC_CAP_BUS_WIDTH_TEST))

			err = mmc_compare_ext_csds(card, MMC_BUS_WIDTH_8);

		else

			err = mmc_bus_test(card, MMC_BUS_WIDTH_8);



		if (err) {

			pr_warn("%s: switch to bus width %d failed\n",

				mmc_hostname(host), MMC_BUS_WIDTH_8);

			return err;

		}

	}



	err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,

			   EXT_CSD_HS_TIMING, EXT_CSD_TIMING_HS400,

			   card->ext_csd.generic_cmd6_time,
@@ -1211,7 +1258,12 @@ static int mmc_select_timing(struct mmc_card *card) 
	if (!mmc_can_ext_csd(card))

		goto bus_speed;



	if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200)

	/* For Enhance Strobe HS400 flow */

	if (card->ext_csd.strobe_support &&

	    card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400 &&

	    card->host->caps & MMC_CAP_8_BIT_DATA)

		err = mmc_select_hs400(card);

	else if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200)

		err = mmc_select_hs200(card);

	else if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS)

		err = mmc_select_hs(card);

include/linux/mmc/card.h

+1 −0
Original line number Diff line number Diff line
@@ -95,6 +95,7 @@ struct mmc_ext_csd { 
	u8			raw_partition_support;	/* 160 */

	u8			raw_rpmb_size_mult;	/* 168 */

	u8			raw_erased_mem_count;	/* 181 */

	u8			strobe_support;		/* 184 */

	u8			raw_ext_csd_structure;	/* 194 */

	u8			raw_card_type;		/* 196 */

	u8			raw_drive_strength;	/* 197 */

include/linux/mmc/mmc.h

+2 −0
Original line number Diff line number Diff line
@@ -248,6 +248,7 @@ struct _mmc_csd { 
#define EXT_CSD_PART_CONFIG		179	/* R/W */

#define EXT_CSD_ERASED_MEM_CONT		181	/* RO */

#define EXT_CSD_BUS_WIDTH		183	/* R/W */

#define EXT_CSD_STROBE_SUPPORT		184	/* RO */

#define EXT_CSD_HS_TIMING		185	/* R/W */

#define EXT_CSD_POWER_CLASS		187	/* R/W */

#define EXT_CSD_REV			192	/* RO */
@@ -337,6 +338,7 @@ struct _mmc_csd { 
#define EXT_CSD_BUS_WIDTH_8	2	/* Card is in 8 bit mode */

#define EXT_CSD_DDR_BUS_WIDTH_4	5	/* Card is in 4 bit DDR mode */

#define EXT_CSD_DDR_BUS_WIDTH_8	6	/* Card is in 8 bit DDR mode */

#define EXT_CSD_BUS_WIDTH_STROBE	0x80	/* Card is in 8 bit DDR mode */



#define EXT_CSD_TIMING_BC	0	/* Backwards compatility */

#define EXT_CSD_TIMING_HS	1	/* High speed */