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Commit 08ee80cc authored by Philip Rakity's avatar Philip Rakity Committed by Chris Ball
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mmc: core: eMMC bus width may not work on all platforms 



CMD19 -- The offical way to validate bus widths from the JEDEC spec
does not work on all platforms.  Some platforms that use PCI/PCIe
to connect their SD controllers are known to fail.

If the quirk MMC_BUS_WIDTH_TEST is not defined we try to figure out
the bus width by reading the ext_csd at different bus widths and
compare this against the ext_csd read in 1 bit mode.  If no ext_csd
is available we default to 1 bit operations.

Code has been tested on mmp2 against 8 bit eMMC and Transcend 2GB
card that is known to not work in 4 bit mode.  The physical pins
on the card are not present to support 4 bit operation.

Signed-off-by: default avatarPhilip Rakity <prakity@marvell.com>
Signed-off-by: default avatarChris Ball <cjb@laptop.org>
parent 4f3d3e9b

drivers/mmc/core/mmc.c

+102 −10
Original line number Diff line number Diff line
@@ -174,14 +174,17 @@ static int mmc_decode_csd(struct mmc_card *card) 
}



/*

 * Read and decode extended CSD.

 * Read extended CSD.

 */

static int mmc_read_ext_csd(struct mmc_card *card)

static int mmc_get_ext_csd(struct mmc_card *card, u8 **new_ext_csd)

{

	int err;

	u8 *ext_csd;



	BUG_ON(!card);

	BUG_ON(!new_ext_csd);



	*new_ext_csd = NULL;



	if (card->csd.mmca_vsn < CSD_SPEC_VER_4)

		return 0;
@@ -199,12 +202,15 @@ static int mmc_read_ext_csd(struct mmc_card *card) 


	err = mmc_send_ext_csd(card, ext_csd);

	if (err) {

		kfree(ext_csd);

		*new_ext_csd = NULL;



		/* If the host or the card can't do the switch,

		 * fail more gracefully. */

		if ((err != -EINVAL)

		 && (err != -ENOSYS)

		 && (err != -EFAULT))

			goto out;

			return err;



		/*

		 * High capacity cards should have this "magic" size
@@ -222,10 +228,24 @@ static int mmc_read_ext_csd(struct mmc_card *card) 
				mmc_hostname(card->host));

			err = 0;

		}

	} else

		*new_ext_csd = ext_csd;



		goto out;

	return err;

}



/*

 * Decode extended CSD.

 */

static int mmc_read_ext_csd(struct mmc_card *card, u8 *ext_csd)

{

	int err = 0;



	BUG_ON(!card);



	if (!ext_csd)

		return 0;



	/* Version is coded in the CSD_STRUCTURE byte in the EXT_CSD register */

	if (card->csd.structure == 3) {

		int ext_csd_struct = ext_csd[EXT_CSD_STRUCTURE];
@@ -372,8 +392,69 @@ static int mmc_read_ext_csd(struct mmc_card *card) 
		card->erased_byte = 0x0;



out:

	return err;

}



static inline void mmc_free_ext_csd(u8 *ext_csd)

{

	kfree(ext_csd);

}





static int mmc_compare_ext_csds(struct mmc_card *card, u8 *ext_csd,

			unsigned bus_width)

{

	u8 *bw_ext_csd;

	int err;



	err = mmc_get_ext_csd(card, &bw_ext_csd);

	if (err)

		return err;



	if ((ext_csd == NULL || bw_ext_csd == NULL)) {

		if (bus_width != MMC_BUS_WIDTH_1)

			err = -EINVAL;

		goto out;

	}



	if (bus_width == MMC_BUS_WIDTH_1)

		goto out;



	/* only compare read only fields */

	err = (!(ext_csd[EXT_CSD_PARTITION_SUPPORT] ==

			bw_ext_csd[EXT_CSD_PARTITION_SUPPORT]) &&

		(ext_csd[EXT_CSD_ERASED_MEM_CONT] ==

			bw_ext_csd[EXT_CSD_ERASED_MEM_CONT]) &&

		(ext_csd[EXT_CSD_REV] ==

			bw_ext_csd[EXT_CSD_REV]) &&

		(ext_csd[EXT_CSD_STRUCTURE] ==

			bw_ext_csd[EXT_CSD_STRUCTURE]) &&

		(ext_csd[EXT_CSD_CARD_TYPE] ==

			bw_ext_csd[EXT_CSD_CARD_TYPE]) &&

		(ext_csd[EXT_CSD_S_A_TIMEOUT] ==

			bw_ext_csd[EXT_CSD_S_A_TIMEOUT]) &&

		(ext_csd[EXT_CSD_HC_WP_GRP_SIZE] ==

			bw_ext_csd[EXT_CSD_HC_WP_GRP_SIZE]) &&

		(ext_csd[EXT_CSD_ERASE_TIMEOUT_MULT] ==

			bw_ext_csd[EXT_CSD_ERASE_TIMEOUT_MULT]) &&

		(ext_csd[EXT_CSD_HC_ERASE_GRP_SIZE] ==

			bw_ext_csd[EXT_CSD_HC_ERASE_GRP_SIZE]) &&

		(ext_csd[EXT_CSD_SEC_TRIM_MULT] ==

			bw_ext_csd[EXT_CSD_SEC_TRIM_MULT]) &&

		(ext_csd[EXT_CSD_SEC_ERASE_MULT] ==

			bw_ext_csd[EXT_CSD_SEC_ERASE_MULT]) &&

		(ext_csd[EXT_CSD_SEC_FEATURE_SUPPORT] ==

			bw_ext_csd[EXT_CSD_SEC_FEATURE_SUPPORT]) &&

		(ext_csd[EXT_CSD_TRIM_MULT] ==

			bw_ext_csd[EXT_CSD_TRIM_MULT]) &&

		memcmp(&ext_csd[EXT_CSD_SEC_CNT],

		       &bw_ext_csd[EXT_CSD_SEC_CNT],

		       4) != 0);

	if (err)

		err = -EINVAL;



out:

	mmc_free_ext_csd(bw_ext_csd);

	return err;

}
@@ -438,6 +519,7 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr, 
	u32 cid[4];

	unsigned int max_dtr;

	u32 rocr;

	u8 *ext_csd = NULL;



	BUG_ON(!host);

	WARN_ON(!host->claimed);
@@ -536,7 +618,11 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr, 
		/*

		 * Fetch and process extended CSD.

		 */

		err = mmc_read_ext_csd(card);



		err = mmc_get_ext_csd(card, &ext_csd);

		if (err)

			goto free_card;

		err = mmc_read_ext_csd(card, ext_csd);

		if (err)

			goto free_card;
@@ -676,13 +762,17 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr, 
					 0);

			if (!err) {

				mmc_set_bus_width(card->host, bus_width);



				/*

				 * If controller can't handle bus width test,

				 * use the highest bus width to maintain

				 * compatibility with previous MMC behavior.

				 * compare ext_csd previously read in 1 bit mode

				 * against ext_csd at new bus width

				 */

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

					break;

					err = mmc_compare_ext_csds(card,

						ext_csd,

						bus_width);

				else

					err = mmc_bus_test(card, bus_width);

				if (!err)

					break;
@@ -730,12 +820,14 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr, 
	if (!oldcard)

		host->card = card;



	mmc_free_ext_csd(ext_csd);

	return 0;



free_card:

	if (!oldcard)

		mmc_remove_card(card);

err:

	mmc_free_ext_csd(ext_csd);



	return err;

}