> -----Original Message-----
> From: Nath, Arindam [mailto:arindam.n...@amd.com]
> Sent: Thursday, March 10, 2011 2:13 PM
> To: subha...@codeaurora.org; c...@laptop.org
> Cc: zhangfei....@gmail.com; prak...@marvell.com; linux-
> m...@vger.kernel.org; Su, Henry; Lu, Aaron; anath....@gmail.com
> Subject: RE: [PATCH v2 07/12] mmc: sd: set current limit for uhs cards
>
> Hi Subhash,
>
>
> > -----Original Message-----
> > From: subha...@codeaurora.org [mailto:subha...@codeaurora.org]
> > Sent: Thursday, March 10, 2011 1:46 PM
> > To: Nath, Arindam; c...@laptop.org
> > Cc: zhangfei....@gmail.com; prak...@marvell.com; linux-
> > m...@vger.kernel.org; Su, Henry; Lu, Aaron; anath....@gmail.com
> > Subject: RE: [PATCH v2 07/12] mmc: sd: set current limit for uhs
> cards
> >
> >
> >
> > > -----Original Message-----
> > > From: Arindam Nath [mailto:anath....@gmail.com] On Behalf Of
> Arindam
> > > Nath
> > > Sent: Friday, March 04, 2011 5:03 PM
> > > To: c...@laptop.org
> > > Cc: zhangfei....@gmail.com; prak...@marvell.com;
> > > subha...@codeaurora.org; linux-mmc@vger.kernel.org;
> henry...@amd.com;
> > > aaron...@amd.com; anath....@gmail.com; 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.n...@amd.com>
> > > ---
> > > 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);
> >
> > I don't think this should be mmc_ops. Max. current limit supported by
> > host
> > should be one of the MMC_CAP*.
> > In your case you can read the "SDHCI_MAX_CURRENT" register during the
> > probe
> > and can set the appropriate MMC_CAP* from below:
> > #define MMC_CAP_MAX_CURRENT_200 (1 << xx)
> > #define MMC_CAP_MAX_CURRENT_400 (1 << (xx+1))
> > #define MMC_CAP_MAX_CURRENT_600 (1 << (xx+2))
> > #define MMC_CAP_MAX_CURRENT_800 (1 << (xx+3))
>
> Good suggestion. Thanks. I will make the changes.
>
> >
> > > +
> > > + 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;
> > > +
> >
> > What will be value of current_limit if (mmc_host_max_current_180 <
> 400)
>
> I referred to table 4-11 of Physical Layer specv3.01. < 400mA should
> fall under the default current limit.
Ok. this is fine.
>
> Thanks,
> Arindam
>
> >
> > > + 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;
> > > }
> > >
> > > +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
> >
> >
>
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