Hi Jackey, > Hi Bing, > > sdhci_add_host() reads host controller's capabilities and initialize host->caps of function > mmc_host_uhs(). So mmc_host_uhs() only return this cached values. So, it does represent host controller's capabilities, not the capabilities of the card. What happens if I have a UHS capable controller and a 2.0 card? The S18R bit will be set in this case, which might cause problem for the card? Thanks, Bing > > Thanks, > Jackey > > -----Original Message----- > From: Bing Zhao [mailto:bzhao@xxxxxxxxxxx] > Sent: Thursday, December 06, 2012 3:14 AM > To: Shen, Jackey; Subhash Jadavani; linux-mmc@xxxxxxxxxxxxxxx > Cc: linux-arm-msm@xxxxxxxxxxxxxxx; Sujit Reddy Thumma > Subject: RE: [PATCH v1 2/3] mmc: sdio: Fix SDIO 3.0 UHS-I initialization sequence > > Hi Jackey, > > > Hi Bing, > > > > The function mmc_host_uhs() will return false and never set bit[24] (S18R) for SDIO 2.0 cards. > > I thought mmc_host_uhs() will return host controller's capabilities, no? > > Thanks, > Bing > > > > > Thanks, > > Jackey > > > > -----Original Message----- > > From: linux-mmc-owner@xxxxxxxxxxxxxxx > > [mailto:linux-mmc-owner@xxxxxxxxxxxxxxx] On Behalf Of Bing Zhao > > Sent: Wednesday, December 05, 2012 5:14 AM > > To: Subhash Jadavani; linux-mmc@xxxxxxxxxxxxxxx > > Cc: linux-arm-msm@xxxxxxxxxxxxxxx; Sujit Reddy Thumma > > Subject: RE: [PATCH v1 2/3] mmc: sdio: Fix SDIO 3.0 UHS-I > > initialization sequence > > > > Hi, > > > > > From: Sujit Reddy Thumma <sthumma@xxxxxxxxxxxxxx> > > > > > > According to UHS-I initialization sequence for SDIO 3.0 cards, the > > > host must set bit[24] (S18R) of OCR register during OCR handshake to > > > know whether the SDIO card is capable of doing 1.8V I/O. > > > > In SDIO 2.0 spec, bit[24] is reserved, "shall be set to 0". > > Setting it to 1 might cause side effect to 2.0 cards. > > Perhaps using a quirk for S18R is more suitable for all combinations. > > > > Regards, > > Bing > > > > > > > > Signed-off-by: Sujit Reddy Thumma <sthumma@xxxxxxxxxxxxxx> > > > Signed-off-by: Subhash Jadavani <subhashj@xxxxxxxxxxxxxx> > > > --- > > > drivers/mmc/core/sdio.c | 22 +++++++++++----------- > > > include/linux/mmc/host.h | 8 ++++++++ > > > 2 files changed, 19 insertions(+), 11 deletions(-) > > > > -- > > 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 > > > > -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
