Re: [U-Boot] [PATCH] mmc: add host_caps checking avoid switch card improperly
Hi Andy, 2011/11/26 Andy Fleming > On Thu, Nov 17, 2011 at 3:31 AM, Macpaul Lin > 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. > > + if (!((mmc->host_caps & MMC_MODE_HS_52MHz) || > > + (mmc->host_caps & MMC_MODE_HS))) > > + return 0; > > + > I wrote this is because I've thought that SD cards usually work at 50MHz when they under high speed mode (MMC_MODE_HS), and MMC cards usually work at 52MHz when they are under high speed mode. I'm not sure if one controller support HS_52MHz for MMC cards will definitely support SD cards under 50MHz. If I'm wrong for the above please correct me. Hence I wrote this to force them working under low speed to avoid problem occur. But I think you're correct, we should use "&&" logic here until there is really a problem for the unbelievable situation I mentioned above that happened. :-p > 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; > > ? > > I'll send patch v2 by using your logic later. Thanks! -- Best regards, Macpaul Lin ___ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
Re: [U-Boot] [PATCH] mmc: add host_caps checking avoid switch card improperly
On Thu, Nov 17, 2011 at 3:31 AM, Macpaul Lin 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 > --- > 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 > > ___ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
[U-Boot] [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 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; + err = sd_switch(mmc, SD_SWITCH_SWITCH, 0, 1, (u8 *)switch_status); if (err) -- 1.7.3.5 ___ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
