Hi Philip, > -----Original Message----- > From: Philip Rakity [mailto:prakity@xxxxxxxxxxx] > Sent: Wednesday, July 06, 2011 9:22 PM > To: linux-mmc@xxxxxxxxxxxxxxx > Cc: Nath, Arindam > Subject: [PATCH V2] mmc: sd.c Set Non Default Drive Strength via > platform > > > V2 > -- > Include host.h change for callback to select_drive_strength > > V1 > -- > Non default Drive Strength cannot be set automatically. > It is a function of the board design and only if there > is a specific platform handler can it be set. The platform > handler needs to take into account the board design. Pass > to the platform code the necessary information. > > For example: The card and host controller may indicate > they support HIGH and LOW drive strength. There is no way > to know what should be chosen without specific board knowledge. > Setting HIGH may lead to reflections and setting LOW may not > be sufficient. > There is no mechanism (like ethernet duplex or speed pulses) > to determine what should be done automatically. > > If no platform handler is defined -- use the default value. > > Signed-off-by: Philip Rakity <prakity@xxxxxxxxxxx> > --- > drivers/mmc/core/sd.c | 68 ++++++++++++++++++++++++++------------ > ------- > include/linux/mmc/host.h | 1 + > 2 files changed, 40 insertions(+), 29 deletions(-) > > diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c > index ff27741..633975f 100644 > --- a/drivers/mmc/core/sd.c > +++ b/drivers/mmc/core/sd.c > @@ -409,52 +409,62 @@ out: > > static int sd_select_driver_type(struct mmc_card *card, u8 *status) > { > - int host_drv_type = 0, card_drv_type = 0; > + int host_drv_type = SD_DRIVER_TYPE_B; > + int card_drv_type = SD_DRIVER_TYPE_B; > + int drive_strength; > int err; > > /* > * If the host doesn't support any of the Driver Types A,C or D, > - * default Driver Type B is used. > + * or there is no board specific handler then default Driver > + * Type B is used. > */ > if (!(card->host->caps & (MMC_CAP_DRIVER_TYPE_A | > MMC_CAP_DRIVER_TYPE_C > | MMC_CAP_DRIVER_TYPE_D))) > return 0; > > - if (card->host->caps & MMC_CAP_DRIVER_TYPE_A) { > - host_drv_type = MMC_SET_DRIVER_TYPE_A; > - if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_A) > - card_drv_type = MMC_SET_DRIVER_TYPE_A; > - else if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_B) > - card_drv_type = MMC_SET_DRIVER_TYPE_B; > - else if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_C) > - card_drv_type = MMC_SET_DRIVER_TYPE_C; > - } else if (card->host->caps & MMC_CAP_DRIVER_TYPE_C) { > - host_drv_type = MMC_SET_DRIVER_TYPE_C; > - if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_C) > - card_drv_type = MMC_SET_DRIVER_TYPE_C; > - } else if (!(card->host->caps & MMC_CAP_DRIVER_TYPE_D)) { > - /* > - * If we are here, that means only the default driver type > - * B is supported by the host. > - */ > - host_drv_type = MMC_SET_DRIVER_TYPE_B; > - if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_B) > - card_drv_type = MMC_SET_DRIVER_TYPE_B; > - else if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_C) > - card_drv_type = MMC_SET_DRIVER_TYPE_C; > - } > + if (!card->host->ops->select_drive_strength) > + return 0; > + > + if (card->host->caps & MMC_CAP_DRIVER_TYPE_A) > + host_drv_type |= SD_DRIVER_TYPE_A; > + > + if (card->host->caps & MMC_CAP_DRIVER_TYPE_C) > + host_drv_type |= SD_DRIVER_TYPE_C; > + > + if (card->host->caps & MMC_CAP_DRIVER_TYPE_D) > + host_drv_type |= SD_DRIVER_TYPE_D; > + > + if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_A) > + card_drv_type |= SD_DRIVER_TYPE_A; > + > + if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_C) > + card_drv_type |= SD_DRIVER_TYPE_C; > + > + if (card->sw_caps.sd3_drv_type & SD_DRIVER_TYPE_D) > + card_drv_type |= SD_DRIVER_TYPE_D; > + > + /* > + * The drive strength that the hardware can support > + * depends on the board design. Pass the appropriate > + * information and let the hardware specific code > + * return what is possible given the options > + */ > + drive_strength = card->host->ops->select_drive_strength( > + card->sw_caps.uhs_max_dtr, > + host_drv_type, card_drv_type); > > - err = mmc_sd_switch(card, 1, 2, card_drv_type, status); > + err = mmc_sd_switch(card, 1, 2, drive_strength, status); > if (err) > return err; > > - if ((status[15] & 0xF) != card_drv_type) { > - printk(KERN_WARNING "%s: Problem setting driver > strength!\n", > + if ((status[15] & 0xF) != drive_strength) { > + printk(KERN_WARNING "%s: Problem setting drive > strength!\n", > mmc_hostname(card->host)); > return 0; > } > > - mmc_set_driver_type(card->host, host_drv_type); > + mmc_set_driver_type(card->host, drive_strength); > > return 0; > } > diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h > index ac3fbac..4913f6c 100644 > --- a/include/linux/mmc/host.h > +++ b/include/linux/mmc/host.h > @@ -139,6 +139,7 @@ struct mmc_host_ops { > int (*start_signal_voltage_switch)(struct mmc_host *host, > struct mmc_ios *ios); > int (*execute_tuning)(struct mmc_host *host); > void (*enable_preset_value)(struct mmc_host *host, bool enable); > + int (*select_drive_strength)(unsigned int max_dtr, int > host_drv, int card_drv); > }; > > struct mmc_card; > -- > 1.7.0.4 > > Looks good to me. Reviewed-by: Arindam Nath <arindam.nath@xxxxxxx> Thanks, Arindam -- 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
