Hi Arindam, On Apr 26, 2011, at 8:24 AM, Philip Rakity wrote: > > On Apr 25, 2011, at 11:36 PM, Nath, Arindam wrote: > >> Hi Philip, >> >> >>> -----Original Message----- >>> From: Philip Rakity [mailto:prakity@xxxxxxxxxxx] >>> Sent: Saturday, April 23, 2011 1:56 AM >>> To: linux-mmc@xxxxxxxxxxxxxxx >>> Cc: Nath, Arindam >>> Subject: [PATCH] sdhci-pxa: add platform specific code for UHS >>> signaling >>> >>> >>> Marvell controller requires 1.8V bit in UHS control register 2 >>> be set when doing UHS. eMMC does not require 1.8V for DDR. >>> add platform code to handle this. >>> >>> Signed-off-by: Philip Rakity <prakity@xxxxxxxxxxx> >>> --- >>> drivers/mmc/host/sdhci-pxa.c | 38 >>> ++++++++++++++++++++++++++++++++++++++ >>> 1 files changed, 38 insertions(+), 0 deletions(-) >>> >>> diff --git a/drivers/mmc/host/sdhci-pxa.c b/drivers/mmc/host/sdhci- >>> pxa.c >>> index 0e64d66..279d677 100644 >>> --- a/drivers/mmc/host/sdhci-pxa.c >>> +++ b/drivers/mmc/host/sdhci-pxa.c >>> @@ -94,7 +94,42 @@ static void platform_reset_exit(struct sdhci_host >>> *host, u8 mask) >>> } >>> } >>> >>> +static int set_uhs_signaling(struct sdhci_host *host, unsigned int >>> uhs) >>> +{ >>> + u16 ctrl_2; >>> + >>> + /* >>> + * Set V18_EN -- UHS modes do not work without this. >>> + * does not change signaling voltage >>> + */ >>> + ctrl_2 = sdhci_readw(host, SDHCI_HOST_CONTROL2); >>> + >>> + /* Select Bus Speed Mode for host */ >>> + ctrl_2 &= ~SDHCI_CTRL_UHS_MASK; >>> + if (uhs == MMC_TIMING_UHS_SDR12) >>> + ctrl_2 |= SDHCI_CTRL_UHS_SDR12; >>> + else if (uhs == MMC_TIMING_UHS_SDR25) >>> + ctrl_2 |= SDHCI_CTRL_UHS_SDR25; >>> + else if (uhs == MMC_TIMING_UHS_SDR50) { >>> + ctrl_2 |= SDHCI_CTRL_UHS_SDR50; >>> + ctrl_2 |= SDHCI_CTRL_VDD_180; >>> + } >>> + else if (uhs == MMC_TIMING_UHS_SDR104) { >>> + ctrl_2 |= SDHCI_CTRL_UHS_SDR104; >>> + ctrl_2 |= SDHCI_CTRL_VDD_180; >>> + } >>> + else if (uhs == MMC_TIMING_UHS_DDR50) { >>> + ctrl_2 |= SDHCI_CTRL_UHS_DDR50; >>> + ctrl_2 |= SDHCI_CTRL_VDD_180; >>> + } >> >> Since SDR12 and SDR25 are also UHS modes, don't we need to set 1.8V signaling for them as well? >> > will double check with hardware folks. Do NOT need to set VDD_180 for low speeds. Code is correct. > >>> + sdhci_writew(host, ctrl_2, SDHCI_HOST_CONTROL2); > > >> >> I am not sure about your controller, but as per the spec, we need to reset SDCLK before enabling 1.8V, and then re-enable SDCLK. Also there is a delay of 5ms between these two. Is that a concern here? >> > > The bit must be set -- no need for 5ms delay since it does not control any power source. Internal. > >>> + pr_debug("%s:%s uhs = %d, ctrl_2 = %04X\n", >>> + __func__, mmc_hostname(host->mmc), uhs, ctrl_2); >>> + return 0; >>> +} >> >> Since, we are just returning 0 from this function, why not use *void* return type instead? >> >> 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 -- 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
