Hi Chris, The following patch https://patchwork.kernel.org/patch/792162/ is tested using Intel EG20T PCH, the Transcend MMC 1bit card can now be detected, read and write to the card successfully. Note : Need to add MMC_CAP_BUS_WIDTH_TEST caps into the SD host controller HW platform code in order to work. Tested-by: tze.siong.mok@xxxxxxxxx -----Original Message----- From: Philip Rakity [mailto:prakity@xxxxxxxxxxx] Sent: Wednesday, May 18, 2011 2:41 AM To: linux-mmc@xxxxxxxxxxxxxxx Cc: Chris Ball; Mok, Tze Siong; Tomoya MORINAGA; Takashi Iwai; Mark Brown Subject: [PATCH] mmc: 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: Philip Rakity <prakity@xxxxxxxxxxx> --- drivers/mmc/core/mmc.c | 135 ++++++++++++++++++++++++++++++++++++++++++++---- 1 files changed, 125 insertions(+), 10 deletions(-) diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c index baab027..42b5045 100644 --- a/drivers/mmc/core/mmc.c +++ b/drivers/mmc/core/mmc.c @@ -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 @@ -222,9 +228,23 @@ 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) { @@ -372,8 +392,92 @@ 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_cmp_ext_csd(u8 *ext_csd, u8 *bw_ext_csd, unsigned bus_width) +{ + if (ext_csd == NULL || bw_ext_csd == NULL) + return bus_width != MMC_BUS_WIDTH_1; + + if (bus_width == MMC_BUS_WIDTH_1) + return 0; + + /* only compare read only fields */ + if (ext_csd[EXT_CSD_PARTITION_SUPPORT] != + bw_ext_csd[EXT_CSD_PARTITION_SUPPORT]) + return -1; + + if (ext_csd[EXT_CSD_ERASED_MEM_CONT] != + bw_ext_csd[EXT_CSD_ERASED_MEM_CONT]) + return -2; + + if (ext_csd[EXT_CSD_REV] != + bw_ext_csd[EXT_CSD_REV]) + return -3; + + if (ext_csd[EXT_CSD_STRUCTURE] != + bw_ext_csd[EXT_CSD_STRUCTURE]) + return -4; + + if (ext_csd[EXT_CSD_CARD_TYPE] != + bw_ext_csd[EXT_CSD_CARD_TYPE]) + return -5; + + if (ext_csd[EXT_CSD_S_A_TIMEOUT] != + bw_ext_csd[EXT_CSD_S_A_TIMEOUT]) + return -6; + + if (ext_csd[EXT_CSD_HC_WP_GRP_SIZE] != + bw_ext_csd[EXT_CSD_HC_WP_GRP_SIZE]) + return -7; + + if (ext_csd[EXT_CSD_ERASE_TIMEOUT_MULT] != + bw_ext_csd[EXT_CSD_ERASE_TIMEOUT_MULT]) + return -8; + + if (ext_csd[EXT_CSD_HC_ERASE_GRP_SIZE] != + bw_ext_csd[EXT_CSD_HC_ERASE_GRP_SIZE]) + return -9; + + if (ext_csd[EXT_CSD_SEC_TRIM_MULT] != + bw_ext_csd[EXT_CSD_SEC_TRIM_MULT]) + return -10; + + if (ext_csd[EXT_CSD_SEC_ERASE_MULT] != + bw_ext_csd[EXT_CSD_SEC_ERASE_MULT]) + return -11; + + if (ext_csd[EXT_CSD_SEC_FEATURE_SUPPORT] != + bw_ext_csd[EXT_CSD_SEC_FEATURE_SUPPORT]) + return -12; + + if (ext_csd[EXT_CSD_TRIM_MULT] != + bw_ext_csd[EXT_CSD_TRIM_MULT]) + return -13; + + return memcmp(&ext_csd[EXT_CSD_SEC_CNT], + &bw_ext_csd[EXT_CSD_SEC_CNT], + 4); +} + +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) + err = mmc_cmp_ext_csd(ext_csd, bw_ext_csd, bus_width); + + mmc_free_ext_csd(bw_ext_csd); return err; } @@ -438,6 +542,7 @@ 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 +641,11 @@ 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; @@ -676,14 +785,18 @@ 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_bus_test(card, bus_width); + err = mmc_compare_ext_csds(card, + ext_csd, + bus_width); + else + err = mmc_bus_test(card, bus_width); if (!err) break; } @@ -730,12 +843,14 @@ 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; } -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
