mmc: Skip changing bus width for MMC cards earlier than version 4.0

Wider bus widths (larger than default 1 bit) appeared in MMC standard
version 4.0. So, for MMC cards of any earlier version trying to change
the bus width (including ext_csd comparison) does not make any sense.
It may work incorrectly and at least cause unnecessary timeouts.
So, just skip the entire bus width related activity for earlier versions.

Signed-off-by: Andrew Gabbasov <andrew_gabbasov@mentor.com>
Tested-by: Alexey Brodkin <abrodkin@synopsys.com>

diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index bdd7894..b8039cd 100644 (file)
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -486,7 +486,7 @@ static int mmc_change_freq(struct mmc *mmc)
        char cardtype;
        int err;
 
-       mmc->card_caps = MMC_MODE_4BIT | MMC_MODE_8BIT;
+       mmc->card_caps = 0;
 
        if (mmc_host_is_spi(mmc))
                return 0;
@@ -495,6 +495,8 @@ static int mmc_change_freq(struct mmc *mmc)
        if (mmc->version < MMC_VERSION_4)
                return 0;
 
+       mmc->card_caps |= MMC_MODE_4BIT | MMC_MODE_8BIT;
+
        err = mmc_send_ext_csd(mmc, ext_csd);
 
        if (err)
@@ -1349,7 +1351,8 @@ static int mmc_startup(struct mmc *mmc)
                        mmc->tran_speed = 50000000;
                else
                        mmc->tran_speed = 25000000;
-       } else {
+       } else if (mmc->version >= MMC_VERSION_4) {
+               /* Only version 4 of MMC supports wider bus widths */
                int idx;
 
                /* An array of possible bus widths in order of preference */