Hi Philip, > -----Original Message----- > From: Philip Rakity [mailto:prakity@xxxxxxxxxxx] > Sent: Wednesday, March 16, 2011 7:56 PM > To: Nath, Arindam > Cc: cjb@xxxxxxxxxx; zhangfei.gao@xxxxxxxxx; subhashj@xxxxxxxxxxxxxx; > linux-mmc@xxxxxxxxxxxxxxx; Su, Henry; Lu, Aaron; anath.amd@xxxxxxxxx > Subject: Re: [PATCH v2 07/12] mmc: sd: set current limit for uhs cards > > > On Mar 4, 2011, at 3:32 AM, Arindam Nath wrote: > > > 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; > > a better name would be get_max_current rather than get_max_current_180 The Max Current Capabilities register reports maximum currents for 1.8V, 3.0V and 3.3V. Since we are only interested in the maximum current at 1.8V, so I have added *_180 to the variable names to make it explicit. > > do you want a test for get_max_current_180 < 400 ? and return 0 have > it do the switch > by setting the value ? As mentioned in the Physical Layer spec v3.01, <400mA falls under the default current limit, so we don't need to set it in case any or all of the above conditions fail. Thanks, Arindam > > + > > + /* 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; > > or > else > current_limit = SD_SET_CURRENT_LIMIT_200; > > + > > + 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)); > > + > > + 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; > > } > > > > better name is sdhci_get_max_current > > > +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; > > SDHCI_MAX_CURRENT_SHIFT is better name. > > > + > > + 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, > > .get_max_current = sdhci_get_max_current; > > }; > > > > > /********************************************************************** > *******\ > > 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
