From 2c3fbf4cbe621680105c5116b37e863a32ce410d Mon Sep 17 00:00:00 2001 From: Macpaul Lin Date: Mon, 28 Nov 2011 16:31:09 +0000 Subject: [PATCH] mmc: add host_caps checking avoid switch card improperly Add a host capability checking to avoid the mmc stack switch the card to HIGHSPEED mode when the card supports HIGHSPEED while the host doesn't. This patch avoid furthur transaction problem when the mmc/sd card runs different mode to the host. Signed-off-by: Macpaul Lin --- drivers/mmc/mmc.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c index 21665ecc5b..98abf1c8e8 100644 --- a/drivers/mmc/mmc.c +++ b/drivers/mmc/mmc.c @@ -785,6 +785,16 @@ retry_scr: if (!(__be32_to_cpu(switch_status[3]) & SD_HIGHSPEED_SUPPORTED)) return 0; + /* + * If the host doesn't support SD_HIGHSPEED, do not switch card to + * HIGHSPEED mode even if the card support SD_HIGHSPPED. + * This can avoid furthur problem when the card runs in different + * mode between the host. + */ + if (!((mmc->host_caps & MMC_MODE_HS_52MHz) && + (mmc->host_caps & MMC_MODE_HS))) + return 0; + err = sd_switch(mmc, SD_SWITCH_SWITCH, 0, 1, (u8 *)switch_status); if (err) -- 2.25.1