On Thu, Nov 17, 2011 at 3:31 AM, Macpaul Lin macpaul@andestech.com wrote:
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 macpaul@andestech.com
drivers/mmc/mmc.c | 10 ++++++++++ 1 files changed, 10 insertions(+), 0 deletions(-)
diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c index 21665ec..ce34d05 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;
Isn't this the wrong logic? It seems like you don't want to switch unless both support high speed. But this logic says to switch if either one does.
Shouldn't it be:
if (!((mmc->host_caps & MMC_MODE_HS_52MHz) && (mmc->host_caps & MMC_MODE_HS))) return 0;
?
Andy
err = sd_switch(mmc, SD_SWITCH_SWITCH, 0, 1, (u8 *)switch_status);
if (err)
1.7.3.5