> -----Original Message----- > From: Seungwon Jeon [mailto:tgih.jun@xxxxxxxxxxx] > Sent: Wednesday, April 25, 2012 10:46 AM > To: 'Subhash Jadavani' > Cc: linux-mmc@xxxxxxxxxxxxxxx; 'Chris Ball'; 'Girish K S' > Subject: RE: [PATCH 2/2] mmc: core: fix the signaling 1.8V for HS200 > > Subhash Jadavani <subhashj@xxxxxxxxxxxxxx> wrote: > > Hi Seungwon, > > > > On 4/23/2012 2:41 PM, Seungwon Jeon wrote: > > > Currently only 1.2V is treated for HS200 mode. If the host has only > > > 1.8V I/O capability not 1.2V, mmc_set_signal_voltage can't be called > > > for 1.8V HS200. EXT_CSD_CARD_TYPE_SDR_1_8V needs to be considered. > > Commit text looks confusing to me. In this change, you are trying to > > set the 1.8V I/O voltage only if there is an error setting the 1.2v > > I/O? Can you please clarify more? > This patch's purpose is to support 1.8V I/O. Origin considers only 1.2V I/O case. > If the host has only 1.8V capability and card type is HS200 1.8V, there is no way > to 1.8V I/O. Thanks for clarification. I was assuming that most of the devices will have I/O voltage always set to 1.8v by host (when device is powered up) but yes, according to spec, it's possible that I/O may be at 3.3v (high voltage) as well. This patch looks good to me. Reviewed-by: Subhash Jadavani <subhashj@xxxxxxxxxxxxxx> Regards, Subhash > > Assuming that card is type of HS200 1.2V and host has 1.2V capability, the 1.2 > I/O voltage will be tried. If it succeeds in 1.2V I/O , we don't need to trying the > 1.8V I/O voltage though 1.8V I/O is possible. > But the 1.8V I/O may be tried in case of 1.2V I/O failure, so error condition is > needed. > > And error is initialized by -EINVAL at the first time. > Thus, if card and host only are capable of 1.8V I/O, we can try to set the 1.8V > I/O regardless of 1.2V I/O result. > > Best regards, > Seungwon Jeon. > > > > > > > Signed-off-by: Seungwon Jeon<tgih.jun@xxxxxxxxxxx> > > > --- > > > drivers/mmc/core/mmc.c | 12 +++++++----- > > > 1 files changed, 7 insertions(+), 5 deletions(-) > > > > > > diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c index > > > ebb9522..71eb320 100644 > > > --- a/drivers/mmc/core/mmc.c > > > +++ b/drivers/mmc/core/mmc.c > > > @@ -732,7 +732,7 @@ static int mmc_select_powerclass(struct mmc_card > *card, > > > */ > > > static int mmc_select_hs200(struct mmc_card *card) > > > { > > > - int idx, err = 0; > > > + int idx, err = -EINVAL; > > > struct mmc_host *host; > > > static unsigned ext_csd_bits[] = { > > > EXT_CSD_BUS_WIDTH_4, > > > @@ -748,10 +748,12 @@ static int mmc_select_hs200(struct mmc_card > *card) > > > host = card->host; > > > > > > if (card->ext_csd.card_type& EXT_CSD_CARD_TYPE_SDR_1_2V&& > > > - host->caps2& MMC_CAP2_HS200_1_2V_SDR) > > > - if (mmc_set_signal_voltage(host, > MMC_SIGNAL_VOLTAGE_120, 0)) > > > - err = mmc_set_signal_voltage(host, > > > - > MMC_SIGNAL_VOLTAGE_180, 0); > > > + host->caps2& MMC_CAP2_HS200_1_2V_SDR) > > > + err = mmc_set_signal_voltage(host, > MMC_SIGNAL_VOLTAGE_120, 0); > > > + > > > + if (err&& card->ext_csd.card_type& > EXT_CSD_CARD_TYPE_SDR_1_8V&& > > > + host->caps2& MMC_CAP2_HS200_1_8V_SDR) > > > + err = mmc_set_signal_voltage(host, > MMC_SIGNAL_VOLTAGE_180, 0); > > > > > > /* If fails try again during next card power cycle */ > > > if (err) > > > > -- > > 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-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
