On 26 September 2012 20:38, Kevin Liu <keyuan.liu@xxxxxxxxx> wrote:
> From: Kevin Liu <kliu5@xxxxxxxxxxx>
>
> Host controller must enable 1.8v signal for UHS modes.
> Otherwise UHS modes won't take effect.
> But mmc core does NOT switch to 1.8v for DDR50 mode.
> So enable the 1.8v signal for mmc DDR50 mode in host
> driver.
>
> Signed-off-by: Kevin Liu <kliu5@xxxxxxxxxxx>
> ---
> drivers/mmc/host/sdhci.c | 9 ++++++++-
> 1 files changed, 8 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 50e7a54..e3de041 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -1529,8 +1529,15 @@ static void sdhci_do_set_ios(struct sdhci_host *host, struct mmc_ios *ios)
> ctrl_2 |= SDHCI_CTRL_UHS_SDR50;
> else if (ios->timing == MMC_TIMING_UHS_SDR104)
> ctrl_2 |= SDHCI_CTRL_UHS_SDR104;
> - else if (ios->timing == MMC_TIMING_UHS_DDR50)
> + else if (ios->timing == MMC_TIMING_UHS_DDR50) {
> + struct mmc_card *card;
> +
> ctrl_2 |= SDHCI_CTRL_UHS_DDR50;
> + card = container_of(&(host->mmc),
> + struct mmc_card, host);
> + if (mmc_card_mmc(card))
> + ctrl_2 |= SDHCI_CTRL_VDD_180;
> + }
If you want to set the voltage to 1.8. It has to be done from the core
layer using the api mmc_set_signal_voltage during the mmc card init.
as it is done for 1.2 volts switch. In the comment (mmc_card_init
function) it is explicitly mentioned
* 1.8V vccq at 3.3V core voltage (vcc) is not required
* in the JEDEC spec for DDR.
can you please check it. Still if you feel its necessary to change the
voltage to 1.8 v, you can do it from mmc_init_card function
> sdhci_writew(host, ctrl_2, SDHCI_HOST_CONTROL2);
> }
> if (!(host->quirks2 & SDHCI_QUIRK2_PRESET_VALUE_BROKEN) &&
> --
> 1.7.0.4
>
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