Hi Subhash, > -----Original Message----- > From: Chris Ball [mailto:cjb@xxxxxxxxxx] > Sent: Friday, August 12, 2011 3:03 AM > To: Subhash Jadavani > Cc: linux-mmc@xxxxxxxxxxxxxxx; linux-arm-msm@xxxxxxxxxxxxxxx; Nath, > Arindam > Subject: Re: [PATCH v1 1/1] mmc: sd: Handle SD3.0 cards not supporting > UHS-I bus speed mode > > Hi Subhash, Arindam, > > On Wed, Aug 10 2011, Subhash Jadavani wrote: > > Here is Essential conditions to indicate Version 3.00 Card > > (SD_SPEC=2 and SD_SPEC3=1) : > > (1) The card shall support CMD6 > > (2) The card shall support CMD8 > > (3) The card shall support CMD42 > > (4) User area capacity shall be up to 2GB (SDSC) or 32GB (SDHC) > > User area capacity shall be more than or equal to 32GB and > > up to 2TB (SDXC) > > (5) Speed Class shall be supported (SDHC or SDXC) > > > > So even if SD card doesn't support any of the newly defined > > UHS-I bus speed mode, it can advertise itself as SD3.0 cards > > as long as it supports all the essential conditions of > > SD3.0 cards. Given this, these type of cards should atleast > > run in High Speed mode @50MHZ if it supports HS. > > > > But current initialization sequence for SD3.0 cards is > > such that these non-UHS-I SD3.0 cards runs in Default > > Speed mode @25MHz. > > > > This patch makes sure that these non-UHS-I SD3.0 cards run > > in High Speed Mode @50MHz. > > > > Tested this patch with SanDisk Extreme SDHC 8GB Class 10 card. > > > > Signed-off-by: Subhash Jadavani <subhashj@xxxxxxxxxxxxxx> > > --- > > drivers/mmc/core/sd.c | 6 +++--- > > 1 files changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c > > index ff27741..e2dcf23 100644 > > --- a/drivers/mmc/core/sd.c > > +++ b/drivers/mmc/core/sd.c > > @@ -306,6 +306,9 @@ static int mmc_read_switch(struct mmc_card *card) > > goto out; > > } > > > > + if (status[13] & 0x02) > > + card->sw_caps.hs_max_dtr = 50000000; > > + > > if (card->scr.sda_spec3) { > > card->sw_caps.sd3_bus_mode = status[13]; > > > > @@ -348,9 +351,6 @@ static int mmc_read_switch(struct mmc_card *card) > > } > > > > card->sw_caps.sd3_curr_limit = status[7]; > > - } else { > > - if (status[13] & 0x02) > > - card->sw_caps.hs_max_dtr = 50000000; > > } > > > > out: > > The patch itself is fine, but please could one of you add some #defines > for the status response bit names and their possible values inside > mmc_read_switch()? It's looking a bit opaque. Do you want to take it up? > > (I know that this patch doesn't introduce any of these magic numbers; > I just think that now is a good time to add documentation for them.) > > Thanks very much, > > - Chris. > -- > Chris Ball <cjb@xxxxxxxxxx> <http://printf.net/> > One Laptop Per Child -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
