On Mar 4, 2011, at 3:32 AM, Arindam Nath wrote:
> This patch adds support for setting driver strength during UHS-I
> initialization prcedure. Since UHS-I cards set S18A (bit 24) in
> response to ACMD41, we use this as a base for UHS-I initialization.
> We modify the parameter list of mmc_sd_get_cid() so that we can
> save the ROCR from ACMD41 to check whether bit 24 is set.
>
> We decide whether the Host Controller supports A, C, or D driver
> type depending on the Capabilities register. We then set the
> appropriate driver type for the card using CMD6 mode 1. As per
> Host Controller spec v3.00, we set driver type for the host only
> if Preset Value Enable in the Host Control2 register is not set.
> SDHCI_HOST_CONTROL has been renamed to SDHCI_HOST_CONTROL1 to
> conform to the spec.
>
> Signed-off-by: Arindam Nath <arindam.nath@xxxxxxx>
> ---
> drivers/mmc/core/core.c | 9 +++
> drivers/mmc/core/core.h | 1 +
> drivers/mmc/core/sd.c | 140 +++++++++++++++++++++++++++++++++++++---------
> drivers/mmc/core/sd.h | 3 +-
> drivers/mmc/core/sdio.c | 3 +-
> drivers/mmc/host/sdhci.c | 48 ++++++++++++----
> drivers/mmc/host/sdhci.h | 10 +++-
> include/linux/mmc/card.h | 4 +
> include/linux/mmc/host.h | 8 +++
> 9 files changed, 186 insertions(+), 40 deletions(-)
>
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 6625c05..daa535a 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -947,6 +947,15 @@ void mmc_set_timing(struct mmc_host *host, unsigned int timing)
> }
>
> /*
> + * Select appropriate driver type for host.
> + */
> +void mmc_set_driver_type(struct mmc_host *host, unsigned int drv_type)
> +{
> + host->ios.drv_type = drv_type;
> + mmc_set_ios(host);
> +}
> +
> +/*
> * Apply power to the MMC stack. This is a two-stage process.
> * First, we enable power to the card without the clock running.
> * We then wait a bit for the power to stabilise. Finally,
> diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h
> index ca1fdde..6114ca5 100644
> --- a/drivers/mmc/core/core.h
> +++ b/drivers/mmc/core/core.h
> @@ -42,6 +42,7 @@ void mmc_set_bus_width_ddr(struct mmc_host *host, unsigned int width,
> unsigned int ddr);
> u32 mmc_select_voltage(struct mmc_host *host, u32 ocr);
> void mmc_set_timing(struct mmc_host *host, unsigned int timing);
> +void mmc_set_driver_type(struct mmc_host *host, unsigned int drv_type);
>
> static inline void mmc_delay(unsigned int ms)
> {
> diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
> index a63956b..f6a4fab 100644
> --- a/drivers/mmc/core/sd.c
> +++ b/drivers/mmc/core/sd.c
> @@ -426,6 +426,86 @@ out:
> return err;
> }
>
> +static int sd_select_driver_type(struct mmc_card *card, u8 *status)
> +{
> + int host_set_drv_type, card_set_drv_type;
> + int err;
> +
> + /*
> + * If the host doesn't support any of the Driver Types A,C or D,
> + * 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_set_drv_type = MMC_SET_DRIVER_TYPE_A;
> + if (card->sw_caps.uhs_drv_type & SD_DRIVER_TYPE_A)
> + card_set_drv_type = MMC_SET_DRIVER_TYPE_A;
> + else if (card->sw_caps.uhs_drv_type & SD_DRIVER_TYPE_C)
> + card_set_drv_type = MMC_SET_DRIVER_TYPE_C;
> + } else if (card->host->caps & MMC_CAP_DRIVER_TYPE_C) {
> + host_set_drv_type = MMC_SET_DRIVER_TYPE_C;
> + if (card->sw_caps.uhs_drv_type & SD_DRIVER_TYPE_C)
> + card_set_drv_type = MMC_SET_DRIVER_TYPE_C;
> + }
> +
> + err = mmc_sd_switch(card, 1, 2, card_set_drv_type, status);
> + if (err)
> + return err;
> +
> + if ((status[15] & 0xF) != card_set_drv_type)
> + printk(KERN_WARNING "%s: Problem setting driver strength!\n",
> + mmc_hostname(card->host));
> + else
> + mmc_set_driver_type(card->host, host_set_drv_type);
> +
> + return 0;
> +}
warning when compiling above routine for possible uninitialized variables
> ost_set_drv_type, card_set_drv_type;
do you want to change the code to add a else ?
eg
> + } else if (card->host->caps & MMC_CAP_DRIVER_TYPE_C) {
> + host_set_drv_type = MMC_SET_DRIVER_TYPE_C;
> + if (card->sw_caps.uhs_drv_type & SD_DRIVER_TYPE_C)
> + card_set_drv_type = MMC_SET_DRIVER_TYPE_C;
> + }
else {
card_set_drv_type = MMC_SET_DRIVER_TYPE_D;
host_set_drv_type = MMC_SET_DRIVER_TYPE_D;
}
>
>
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