From ca8e99b32e3863c98ac958617cc157a00bf445b8 Mon Sep 17 00:00:00 2001 From: Philip Rakity Date: Wed, 6 Jul 2011 08:51:32 -0700 Subject: [PATCH] mmc: core: Set non-default Drive Strength via platform hook 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 suffice. 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 Reviewed-by: Arindam Nath Signed-off-by: Chris Ball --- 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 ff2774128aa9..633975ff2bb3 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; - err = mmc_sd_switch(card, 1, 2, card_drv_type, status); + 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, 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 9f9a4c64cde7..0f83858147a6 100644 --- a/include/linux/mmc/host.h +++ b/include/linux/mmc/host.h @@ -148,6 +148,7 @@ 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;