From 7798f6dbd5e1a3030ed81a81da5dfb57c3307cac Mon Sep 17 00:00:00 2001 From: Andy Fleming Date: Wed, 31 Oct 2012 19:02:38 +0000 Subject: mmc: Properly determine maximum supported bus width At some point, a confusion arose about the use of the bit definitions in host_caps for bus widths, and the value in ext_csd. By coincidence, a simple shift could convert between one and the other: MMC_MODE_1BIT = 0, EXT_CSD_BUS_WIDTH_1 = 0 MMC_MODE_4BIT = 0x100, EXT_CSD_BUS_WIDTH_4 = 1 MMC_MODE_8BIT = 0x200, EXT_CSD_BUS_WIDTH_8 = 2 However, as host_caps is a bitmask of supported things, there is not, in fact, a one-to-one correspondence. host_caps is capable of containing MODE_4BIT | MODE_8BIT, so nonsensical things were happening where we would try to set the bus width to 12. The new code clarifies the very different namespaces: host_caps/card_caps = bitmask (MMC_MODE_*) ext CSD fields are just an index (EXT_CSD_BUS_WIDTH_*) mmc->bus_width integer number of bits (1, 4, 8) We create arrays to map between the namespaces, like in Linux. Signed-off-by: Andy Fleming Tested-by: Jaehoon Chung Tested-by: Stephen Warren --- drivers/mmc/mmc.c | 47 +++++++++++++++++++++++++++++++++++------------ 1 file changed, 35 insertions(+), 12 deletions(-) diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c index 59dc5894c9..72e8ce6da4 100644 --- a/drivers/mmc/mmc.c +++ b/drivers/mmc/mmc.c @@ -868,7 +868,7 @@ static void mmc_set_bus_width(struct mmc *mmc, uint width) static int mmc_startup(struct mmc *mmc) { - int err, width; + int err; uint mult, freq; u64 cmult, csize, capacity; struct mmc_cmd cmd; @@ -1087,21 +1087,44 @@ static int mmc_startup(struct mmc *mmc) else mmc->tran_speed = 25000000; } else { - width = ((mmc->host_caps & MMC_MODE_MASK_WIDTH_BITS) >> - MMC_MODE_WIDTH_BITS_SHIFT); - for (; width >= 0; width--) { - /* Set the card to use 4 bit*/ + int idx; + + /* An array of possible bus widths in order of preference */ + static unsigned ext_csd_bits[] = { + EXT_CSD_BUS_WIDTH_8, + EXT_CSD_BUS_WIDTH_4, + EXT_CSD_BUS_WIDTH_1, + }; + + /* An array to map CSD bus widths to host cap bits */ + static unsigned ext_to_hostcaps[] = { + [EXT_CSD_BUS_WIDTH_4] = MMC_MODE_4BIT, + [EXT_CSD_BUS_WIDTH_8] = MMC_MODE_8BIT, + }; + + /* An array to map chosen bus width to an integer */ + static unsigned widths[] = { + 8, 4, 1, + }; + + for (idx=0; idx < ARRAY_SIZE(ext_csd_bits); idx++) { + unsigned int extw = ext_csd_bits[idx]; + + /* + * Check to make sure the controller supports + * this bus width, if it's more than 1 + */ + if (extw != EXT_CSD_BUS_WIDTH_1 && + !(mmc->host_caps & ext_to_hostcaps[extw])) + continue; + err = mmc_switch(mmc, EXT_CSD_CMD_SET_NORMAL, - EXT_CSD_BUS_WIDTH, width); + EXT_CSD_BUS_WIDTH, extw); if (err) continue; - if (!width) { - mmc_set_bus_width(mmc, 1); - break; - } else - mmc_set_bus_width(mmc, 4 * width); + mmc_set_bus_width(mmc, widths[idx]); err = mmc_send_ext_csd(mmc, test_csd); if (!err && ext_csd[EXT_CSD_PARTITIONING_SUPPORT] \ @@ -1115,7 +1138,7 @@ static int mmc_startup(struct mmc *mmc) && memcmp(&ext_csd[EXT_CSD_SEC_CNT], \ &test_csd[EXT_CSD_SEC_CNT], 4) == 0) { - mmc->card_caps |= width; + mmc->card_caps |= ext_to_hostcaps[extw]; break; } } -- cgit