From fc5b32fbf3bd43dabaf409e424e0bfb9a1b4df26 Mon Sep 17 00:00:00 2001
From: Andrew Gabbasov <andrew_gabbasov@mentor.com>
Date: Thu, 25 Dec 2014 10:22:25 -0600
Subject: [PATCH] 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>
---
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 bdd7894231..b8039cd092 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)
@@ -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 */
--
2.39.5