Hi Subhash, > -----Original Message----- > From: Subhash Jadavani [mailto:subhashj@xxxxxxxxxxxxxx] > Sent: Monday, March 21, 2011 1:14 PM > To: Nath, Arindam; cjb@xxxxxxxxxx > Cc: zhangfei.gao@xxxxxxxxx; prakity@xxxxxxxxxxx; linux- > mmc@xxxxxxxxxxxxxxx; Su, Henry; Lu, Aaron; anath.amd@xxxxxxxxx > Subject: RE: [PATCH v2 07/12] mmc: sd: set current limit for uhs cards > > > > > -----Original Message----- > > From: Arindam Nath [mailto:anath.amd@xxxxxxxxx] On Behalf Of Arindam > > Nath > > Sent: Friday, March 04, 2011 5:03 PM > > To: cjb@xxxxxxxxxx > > Cc: zhangfei.gao@xxxxxxxxx; prakity@xxxxxxxxxxx; > > subhashj@xxxxxxxxxxxxxx; linux-mmc@xxxxxxxxxxxxxxx; henry.su@xxxxxxx; > > aaron.lu@xxxxxxx; anath.amd@xxxxxxxxx; Arindam Nath > > Subject: [PATCH v2 07/12] mmc: sd: set current limit for uhs cards > > > > We decide on the current limit to be set for the card based on the > > Capability of Host Controller to provide current at 1.8V signalling, > > and the maximum current limit of the card as indicated by CMD6 > > mode 0. We then set the current limit for the card using CMD6 mode 1. > > > > Signed-off-by: Arindam Nath <arindam.nath@xxxxxxx> > > --- > > drivers/mmc/core/sd.c | 45 > > +++++++++++++++++++++++++++++++++++++++++++++ > > drivers/mmc/host/sdhci.c | 24 ++++++++++++++++++++++++ > > include/linux/mmc/card.h | 9 +++++++++ > > include/linux/mmc/host.h | 1 + > > 4 files changed, 79 insertions(+), 0 deletions(-) > > > > diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c > > index ec0d8e6..df98a2c 100644 > > --- a/drivers/mmc/core/sd.c > > +++ b/drivers/mmc/core/sd.c > > @@ -550,6 +550,46 @@ static int sd_set_bus_speed_mode(struct mmc_card > > *card, u8 *status) > > return 0; > > } > > > > +static int sd_set_current_limit(struct mmc_card *card, u8 *status) > > +{ > > + struct mmc_host *host = card->host; > > + int mmc_host_max_current_180, current_limit; > > + int err; > > + > > + /* sanity check */ > > + if (!host->ops->get_max_current_180) > > + return 0; > > + > > + /* Maximum current supported by host at 1.8V */ > > + mmc_host_max_current_180 = host->ops->get_max_current_180(host); > > + > > + if (mmc_host_max_current_180 >= 800) { > > + if (card->sw_caps.uhs_curr_limit & SD_MAX_CURRENT_800) > > + current_limit = SD_SET_CURRENT_LIMIT_800; > > + else if (card->sw_caps.uhs_curr_limit & SD_MAX_CURRENT_600) > > + current_limit = SD_SET_CURRENT_LIMIT_600; > > + else if (card->sw_caps.uhs_curr_limit & SD_MAX_CURRENT_400) > > + current_limit = SD_SET_CURRENT_LIMIT_400; > > + } else if (mmc_host_max_current_180 >= 600) { > > + if (card->sw_caps.uhs_curr_limit & SD_MAX_CURRENT_600) > > + current_limit = SD_SET_CURRENT_LIMIT_600; > > + else if (card->sw_caps.uhs_curr_limit & SD_MAX_CURRENT_400) > > + current_limit = SD_SET_CURRENT_LIMIT_400; > > + } else if (mmc_host_max_current_180 >= 400) > > + if (card->sw_caps.uhs_curr_limit & SD_MAX_CURRENT_400) > > + current_limit = SD_SET_CURRENT_LIMIT_400; > > + > > + err = mmc_sd_switch(card, 1, 3, current_limit, status); > > + if (err) > > + return err; > > + > > + if (((status[15] >> 4) & 0x0F) != current_limit) > > + printk(KERN_WARNING "%s: Problem setting current limit!\n", > > + mmc_hostname(card->host)); > > This is what SD3.01 spec says: > "Current limit switch is only for SDR50, SDR104 and DDR50. Current > limit > does not act on the card in SDR12 and SDR25 modes." > > But in this function you are not checking for the currently selected > bus > speed mode. If let's say you are in SDR12/SDR25 mode and if host > supports > MAX_CURRENT_800 then this function will try to the current limit to 800 > but > card won't switch to it as SDR12/SDR25 mode doen't allow the current > switch. > > So basically your following check will always print the warning for > SDR12/SDR25 mode. > > if (((status[15] >> 4) & 0x0F) != current_limit) > printk(KERN_WARNING "%s: Problem setting current limit!\n", > mmc_hostname(card->host)); > > So in this function you should also check the current bus speed mode. > If > current bus_speed_mode is SDR12/SDR25/legacy then you should select the > current limit to 200ma and for SDR104/SDR50/DDR50, you should select it > depending on the host's Max. current limit. Thanks for the correction. Yes, I verified from the spec what you said. I will modify the code accordingly. Thanks, Arindam > > > > + > > + return 0; > > +} > > + > > /* > > * UHS-I specific initialization procedure > > */ > > @@ -590,6 +630,11 @@ static int mmc_sd_init_uhs_card(struct mmc_card > > *card) > > > > /* Set bus speed mode of the card */ > > err = sd_set_bus_speed_mode(card, status); > > + if (err) > > + goto out; > > + > > + /* Set current limit for the card */ > > + err = sd_set_current_limit(card, status); > > > > out: > > kfree(status); > > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c > > index f127fa2..245cc39 100644 > > --- a/drivers/mmc/host/sdhci.c > > +++ b/drivers/mmc/host/sdhci.c > > @@ -1462,12 +1462,36 @@ static int > > sdhci_start_signal_voltage_switch(struct mmc_host *mmc) > > return -EAGAIN; > > } > > > > +static int sdhci_get_max_current_180(struct mmc_host *mmc) > > +{ > > + struct sdhci_host *host; > > + u32 max_current_caps; > > + unsigned long flags; > > + int max_current_180; > > + > > + host = mmc_priv(mmc); > > + > > + spin_lock_irqsave(&host->lock, flags); > > + > > + max_current_caps = sdhci_readl(host, SDHCI_MAX_CURRENT); > > + > > + spin_unlock_irqrestore(&host->lock, flags); > > + > > + /* Maximum current is 4 times the register value for 1.8V */ > > + max_current_180 = ((max_current_caps & > > SDHCI_MAX_CURRENT_180_MASK) >> > > + SDHCI_MAX_CURRENT_180_SHIFT) * > > + SDHCI_MAX_CURRENT_MULTIPLIER; > > + > > + return max_current_180; > > +} > > + > > static const struct mmc_host_ops sdhci_ops = { > > .request = sdhci_request, > > .set_ios = sdhci_set_ios, > > .get_ro = sdhci_get_ro, > > .enable_sdio_irq = sdhci_enable_sdio_irq, > > .start_signal_voltage_switch = > > sdhci_start_signal_voltage_switch, > > + .get_max_current_180 = sdhci_get_max_current_180, > > }; > > > > > > > /********************************************************************** > > *******\ > > diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h > > index 0b24c41..a6811ae 100644 > > --- a/include/linux/mmc/card.h > > +++ b/include/linux/mmc/card.h > > @@ -98,6 +98,15 @@ struct sd_switch_caps { > > #define SD_DRIVER_TYPE_C 0x04 > > #define SD_DRIVER_TYPE_D 0x08 > > unsigned int uhs_curr_limit; > > +#define SD_SET_CURRENT_LIMIT_200 0 > > +#define SD_SET_CURRENT_LIMIT_400 1 > > +#define SD_SET_CURRENT_LIMIT_600 2 > > +#define SD_SET_CURRENT_LIMIT_800 3 > > + > > +#define SD_MAX_CURRENT_200 (1 << SD_SET_CURRENT_LIMIT_200) > > +#define SD_MAX_CURRENT_400 (1 << SD_SET_CURRENT_LIMIT_400) > > +#define SD_MAX_CURRENT_600 (1 << SD_SET_CURRENT_LIMIT_600) > > +#define SD_MAX_CURRENT_800 (1 << SD_SET_CURRENT_LIMIT_800) > > }; > > > > struct sdio_cccr { > > diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h > > index 4dfff6d..e84cd05 100644 > > --- a/include/linux/mmc/host.h > > +++ b/include/linux/mmc/host.h > > @@ -128,6 +128,7 @@ struct mmc_host_ops { > > void (*init_card)(struct mmc_host *host, struct mmc_card *card); > > > > int (*start_signal_voltage_switch)(struct mmc_host *host); > > + int (*get_max_current_180)(struct mmc_host *mmc); > > }; > > > > struct mmc_card; > > -- > > 1.7.1 > > -- 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
