[U-Boot] [PATCH 2/2] mmc: Skip changing bus width for MMC cards earlier than version 4.0

[Andrew Gabbasov]

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 at mentor.com>
Tested-by: Alexey Brodkin <abrodkin at synopsys.com>
---
 drivers/mmc/mmc.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index c0cf318..14d6a13 100644
--- 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)
@@ -1107,7 +1109,8 @@ 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 */
-- 
2.1.0