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authorAndy Fleming <afleming@freescale.com>2012-10-31 19:02:38 +0000
committerAndy Fleming <afleming@freescale.com>2012-11-27 17:48:46 -0600
commit7798f6dbd5e1a3030ed81a81da5dfb57c3307cac (patch)
tree44d6edde9d71397c2d4e1bfa82dbf0954048f117 /drivers
parented80c931ba7781e6605b9bdaa2a0d58ef365fe71 (diff)
downloadu-boot-linaro-stable-7798f6dbd5e1a3030ed81a81da5dfb57c3307cac.tar.gz
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 <afleming@freescale.com> Tested-by: Jaehoon Chung <jh80.chung@samsung.com> Tested-by: Stephen Warren <swarren@nvidia.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/mmc/mmc.c47
1 files changed, 35 insertions, 12 deletions
diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index 59dc5894c..72e8ce6da 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;
}
}