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mmc: sdhci: enable preset value after uhs initialization

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According to the Host Controller spec v3.00, setting Preset Value Enable
in the Host Control2 register lets SDCLK Frequency Select, Clock Generator
Select and Driver Strength Select to be set automatically by the Host
Controller based on the UHS-I mode set. This patch enables this feature.
Since Preset Value Enable makes sense only for UHS-I cards, we enable this
feature after successfull UHS-I initialization. We also reset Preset Value
Enable next time before initialization.

Tested by Zhangfei Gao with a Toshiba uhs card and general hs card,
on mmp2 in SDMA mode.

Signed-off-by: Arindam Nath <[email protected]>
Reviewed-by: Philip Rakity <[email protected]>
Tested-by: Philip Rakity <[email protected]>
Acked-by: Zhangfei Gao <[email protected]>
Signed-off-by: Chris Ball <[email protected]>
This commit is contained in:
Arindam Nath 2011-05-05 12:19:05 +05:30 • committed by Chris Ball
commit 4d55c5a13a
3 changed files with 44 additions and 0 deletions
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11
drivers/mmc/core/sd.c
View file

@ -925,6 +925,13 @@ static int mmc_sd_init_card(struct mmc_host *host, u32 ocr,
/* Card is an ultra-high-speed card */
mmc_sd_card_set_uhs(card);
/*
* Since initialization is now complete, enable preset
* value registers for UHS-I cards.
*/
if (host->ops->enable_preset_value)
host->ops->enable_preset_value(host, true);
} else {
/*
* Attempt to change to high-speed (if supported)
@ -1095,6 +1102,10 @@ int mmc_attach_sd(struct mmc_host *host)
if (err)
return err;
/* Disable preset value enable if already set since last time */
if (host->ops->enable_preset_value)
host->ops->enable_preset_value(host, false);
err = mmc_send_app_op_cond(host, 0, &ocr);
if (err)
return err;

32
drivers/mmc/host/sdhci.c
View file

@ -1649,6 +1649,37 @@ out:
return err;
}
static void sdhci_enable_preset_value(struct mmc_host *mmc, bool enable)
{
struct sdhci_host *host;
u16 ctrl;
unsigned long flags;
host = mmc_priv(mmc);
/* Host Controller v3.00 defines preset value registers */
if (host->version < SDHCI_SPEC_300)
return;
spin_lock_irqsave(&host->lock, flags);
ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
/*
* We only enable or disable Preset Value if they are not already
* enabled or disabled respectively. Otherwise, we bail out.
*/
if (enable && !(ctrl & SDHCI_CTRL_PRESET_VAL_ENABLE)) {
ctrl |= SDHCI_CTRL_PRESET_VAL_ENABLE;
sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
} else if (!enable && (ctrl & SDHCI_CTRL_PRESET_VAL_ENABLE)) {
ctrl &= ~SDHCI_CTRL_PRESET_VAL_ENABLE;
sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
}
spin_unlock_irqrestore(&host->lock, flags);
}
static const struct mmc_host_ops sdhci_ops = {
.request = sdhci_request,
.set_ios = sdhci_set_ios,
@ -1656,6 +1687,7 @@ static const struct mmc_host_ops sdhci_ops = {
.enable_sdio_irq = sdhci_enable_sdio_irq,
.start_signal_voltage_switch = sdhci_start_signal_voltage_switch,
.execute_tuning = sdhci_execute_tuning,
.enable_preset_value = sdhci_enable_preset_value,
};
/*****************************************************************************\