Hi Philip, > -----Original Message----- > From: Philip Rakity [mailto:prakity@xxxxxxxxxxx] > Sent: Saturday, March 05, 2011 10:27 AM > To: Nath, Arindam > Cc: cjb@xxxxxxxxxx; zhangfei.gao@xxxxxxxxx; subhashj@xxxxxxxxxxxxxx; > linux-mmc@xxxxxxxxxxxxxxx; Su, Henry; Lu, Aaron; anath.amd@xxxxxxxxx > Subject: Re: [PATCH v2 05/12] mmc: sdhci: reset sdclk before setting > high speed enable > > > On Mar 4, 2011, at 3:32 AM, Arindam Nath wrote: > > > As per Host Controller spec v3.00, we reset SDCLK before setting > > High Speed Enable, and then set it back to avoid generating clock > > gliches. > > > > Signed-off-by: Arindam Nath <arindam.nath@xxxxxxx> > > --- > > drivers/mmc/host/sdhci.c | 25 ++++++++++++++++++++++--- > > 1 files changed, 22 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c > > index 1645687..5d3bb11 100644 > > --- a/drivers/mmc/host/sdhci.c > > +++ b/drivers/mmc/host/sdhci.c > > @@ -1277,13 +1277,12 @@ static void sdhci_set_ios(struct mmc_host > *mmc, struct mmc_ios *ios) > > else > > ctrl &= ~SDHCI_CTRL_HISPD; > > > > - sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL1); > > - > > if (host->version >= SDHCI_SPEC_300) { > > u16 ctrl_2; > > > > ctrl_2 = sdhci_readw(host, SDHCI_HOST_CONTROL2); > > if (!(ctrl_2 & SDHCI_CTRL_PRESET_VAL_ENABLE)) { > > + sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL1); > > /* > > * We only need to set Driver Strength if the > > * preset value enable is not set. > > @@ -1294,8 +1293,28 @@ static void sdhci_set_ios(struct mmc_host > *mmc, struct mmc_ios *ios) > > ctrl_2 |= SDHCI_CTRL_DRV_TYPE_C; > > > > sdhci_writew(host, ctrl_2, SDHCI_HOST_CONTROL2); > > + } else { > > + /* > > + * According to SDHC Spec v3.00, if the Preset Value > > + * Enable in the Host Control 2 register is set, we > > + * need to reset SD Clock Enable before changing High > > + * Speed Enable to avoid generating clock gliches. > > + */ > > + u16 clk; > > + > > + /* Reset SD Clock Enable */ > > + clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL); > > + clk &= ~SDHCI_CLOCK_CARD_EN; > > + sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL); > > + > > + sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL1); > > + > > + /* Re-enable SD Clock */ > > + clk |= SDHCI_CLOCK_CARD_EN; > > + sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL); > > Need to ensure clock is stable before using it ---- use sdhci_set_clock Thanks for the suggestion. I will add the modification in next version. Regards, Arindam > > > } > > > > > - } > > + } else > > + sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL1); > > > > /* > > * Some (ENE) controllers go apeshit on some ios operation, > > -- > > 1.7.1 > > > -- 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
