mmc: Fix handling of bus widths and DDR card capabilities

If the MMC_MODE_DDR_52MHz flag is set in card capabilities bitmask,
it is never cleared, even if switching to DDR mode fails, and if
the controller driver uses this flag to check the DDR mode, it can
take incorrect actions.

Also, DDR related checks in mmc_startup() incorrectly handle the case
when the host controller does not support some bus widths (e.g. can't
support 8 bits), since the host_caps is checked for DDR bit, but not
bus width bits.

This fix clearly separates using of card_caps bitmask, having there
the flags for the capabilities, that the card can support, and actual
operation mode, described outside of card_caps (i.e. bus_width and
ddr_mode fields in mmc structure). Separate host controller drivers
may need to be updated to use the actual flags. Respectively,
the capabilities checks in mmc_startup are made more correct and clear.

Also, some clean up is made with errors handling and code syntax layout.

Signed-off-by: Andrew Gabbasov <andrew_gabbasov@mentor.com>

1 files changed, 31 insertions, 21 deletions

diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index 99f03c9..a290031 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -159,7 +159,7 @@ int mmc_set_blocklen(struct mmc *mmc, int len)
 {
 	struct mmc_cmd cmd;
 
-	if (mmc->card_caps & MMC_MODE_DDR_52MHz)
+	if (mmc->ddr_mode)
 		return 0;
 
 	cmd.cmdidx = MMC_CMD_SET_BLOCKLEN;
@@ -486,7 +486,7 @@ static int mmc_change_freq(struct mmc *mmc)
 	char cardtype;
 	int err;
 
-	mmc->card_caps = 0;
+	mmc->card_caps = MMC_MODE_4BIT | MMC_MODE_8BIT;
 
 	if (mmc_host_is_spi(mmc))
 		return 0;
@@ -1121,8 +1121,10 @@ static int mmc_startup(struct mmc *mmc)
 
 		/* An array to map CSD bus widths to host cap bits */
 		static unsigned ext_to_hostcaps[] = {
-			[EXT_CSD_DDR_BUS_WIDTH_4] = MMC_MODE_DDR_52MHz,
-			[EXT_CSD_DDR_BUS_WIDTH_8] = MMC_MODE_DDR_52MHz,
+			[EXT_CSD_DDR_BUS_WIDTH_4] =
+				MMC_MODE_DDR_52MHz | MMC_MODE_4BIT,
+			[EXT_CSD_DDR_BUS_WIDTH_8] =
+				MMC_MODE_DDR_52MHz | MMC_MODE_8BIT,
 			[EXT_CSD_BUS_WIDTH_4] = MMC_MODE_4BIT,
 			[EXT_CSD_BUS_WIDTH_8] = MMC_MODE_8BIT,
 		};
@@ -1134,13 +1136,13 @@ static int mmc_startup(struct mmc *mmc)
 
 		for (idx=0; idx < ARRAY_SIZE(ext_csd_bits); idx++) {
 			unsigned int extw = ext_csd_bits[idx];
+			unsigned int caps = ext_to_hostcaps[extw];
 
 			/*
-			 * Check to make sure the controller supports
-			 * this bus width, if it's more than 1
+			 * Check to make sure the card and controller support
+			 * these capabilities
 			 */
-			if (extw != EXT_CSD_BUS_WIDTH_1 &&
-					!(mmc->cfg->host_caps & ext_to_hostcaps[extw]))
+			if ((mmc->card_caps & caps) != caps)
 				continue;
 
 			err = mmc_switch(mmc, EXT_CSD_CMD_SET_NORMAL,
@@ -1149,26 +1151,33 @@ static int mmc_startup(struct mmc *mmc)
 			if (err)
 				continue;
 
+			mmc->ddr_mode = (caps & MMC_MODE_DDR_52MHz) ? 1 : 0;
 			mmc_set_bus_width(mmc, widths[idx]);
 
 			err = mmc_send_ext_csd(mmc, test_csd);
+
+			if (err)
+				continue;
+
 			/* Only compare read only fields */
-			if (!err && ext_csd[EXT_CSD_PARTITIONING_SUPPORT] \
-				    == test_csd[EXT_CSD_PARTITIONING_SUPPORT]
-				 && ext_csd[EXT_CSD_HC_WP_GRP_SIZE] \
-				    == test_csd[EXT_CSD_HC_WP_GRP_SIZE] \
-				 && ext_csd[EXT_CSD_REV] \
-				    == test_csd[EXT_CSD_REV]
-				 && ext_csd[EXT_CSD_HC_ERASE_GRP_SIZE] \
-				    == test_csd[EXT_CSD_HC_ERASE_GRP_SIZE]
-				 && memcmp(&ext_csd[EXT_CSD_SEC_CNT], \
-					&test_csd[EXT_CSD_SEC_CNT], 4) == 0) {
-
-				mmc->card_caps |= ext_to_hostcaps[extw];
+			if (ext_csd[EXT_CSD_PARTITIONING_SUPPORT]
+				== test_csd[EXT_CSD_PARTITIONING_SUPPORT] &&
+			    ext_csd[EXT_CSD_HC_WP_GRP_SIZE]
+				== test_csd[EXT_CSD_HC_WP_GRP_SIZE] &&
+			    ext_csd[EXT_CSD_REV]
+				== test_csd[EXT_CSD_REV] &&
+			    ext_csd[EXT_CSD_HC_ERASE_GRP_SIZE]
+				== test_csd[EXT_CSD_HC_ERASE_GRP_SIZE] &&
+			    memcmp(&ext_csd[EXT_CSD_SEC_CNT],
+				   &test_csd[EXT_CSD_SEC_CNT], 4) == 0)
 				break;
-			}
+			else
+				err = SWITCH_ERR;
 		}
 
+		if (err)
+			return err;
+
 		if (mmc->card_caps & MMC_MODE_HS) {
 			if (mmc->card_caps & MMC_MODE_HS_52MHz)
 				mmc->tran_speed = 52000000;
@@ -1324,6 +1333,7 @@ int mmc_start_init(struct mmc *mmc)
 	if (err)
 		return err;
 
+	mmc->ddr_mode = 0;
 	mmc_set_bus_width(mmc, 1);
 	mmc_set_clock(mmc, 1);