Hi Philip, > -----Original Message----- > From: Philip Rakity [mailto:prakity@xxxxxxxxxxx] > Sent: Wednesday, March 16, 2011 8:48 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 16, 2011, at 8:00 AM, Nath, Arindam wrote: > > > Hi Philip, > > > > > >> -----Original Message----- > >> From: Philip Rakity [mailto:prakity@xxxxxxxxxxx] > >> Sent: Wednesday, March 16, 2011 8:22 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 16, 2011, at 7:32 AM, Nath, Arindam wrote: > >> > >>> 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. > >> > >> understand but that is the usage now and if we need to extend the > code > >> the name becomes misleading. > > > > Okay. I will remove *_180 in next version. > > > >>> > >>>> > >>>> 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. > >> > >> if future cards have memory or power is not removed they will they > >> retain the old setting ? if so better to explicitly initialize. > > > > Can you please elaborate this a little further? > > Power to the sd slot is supplied via a regulator. This is turned on at > power on. > sometime in the future a reboot is done. power is NOT removed. The > device does not reset > into the default state. Have seen this on some boards. Thanks for the explanation. I will modify code to set the default current limit for the card. Regards, Arindam > > > > > Thanks, > > Arindam > > > >> > >>> > >>> 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
