RE: [PATCH v2 10/12] mmc: sdhci: enable preset value after uhs initialization

[<subhashj@codeaurora.org>]

> -----Original Message-----
> From: linux-mmc-owner@vger.kernel.org [mailto:linux-mmc-
> owner@vger.kernel.org] On Behalf Of Arindam Nath
> Sent: Friday, March 04, 2011 5:03 PM
> To: cjb@laptop.org
> Cc: zhangfei.gao@gmail.com; prakity@marvell.com;
> subhashj@codeaurora.org; linux-mmc@vger.kernel.org; henry.su@amd.com;
> aaron.lu@amd.com; anath.amd@gmail.com; Arindam Nath
> Subject: [PATCH v2 10/12] mmc: sdhci: enable preset value after uhs
> initialization
> 
> 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.
> We also reset Preset Value Enable when the card is removed from the
> slot.

What does this preset_value means? Is this defined in SD3.01 spec? I think
it looks like specific to your controller (sdhci). If it's specific to your
controller then this new mmc_ops should not be added.


> 
> Signed-off-by: Arindam Nath <arindam.nath@amd.com>
> ---
>  drivers/mmc/core/sd.c    |    7 +++++++
>  drivers/mmc/host/sdhci.c |   36 ++++++++++++++++++++++++++++++++++++
>  include/linux/mmc/host.h |    1 +
>  3 files changed, 44 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
> index 1e2d157..ae7a771 100644
> --- a/drivers/mmc/core/sd.c
> +++ b/drivers/mmc/core/sd.c
> @@ -962,6 +962,13 @@ static int mmc_sd_init_card(struct mmc_host *host,
> u32 ocr,
>  		}
>  	}
> 
> +	/*
> +	 * Since initialization is now complete, enable preset
> +	 * value registers.
> +	 */
> +	if (host->ops->enable_preset_value)
> +		host->ops->enable_preset_value(host);
> +
>  	host->card = card;
>  	return 0;
> 
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 8f4f102..1f6e4ad 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -1602,6 +1602,40 @@ out:
>  	spin_unlock_irqrestore(&host->lock, flags);
>  }
> 
> +static void sdhci_enable_preset_value(struct mmc_host *mmc)
> +{
> +	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);
> +	ctrl |= SDHCI_CTRL_PRESET_VAL_ENABLE;
> +	sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
> +
> +	spin_unlock_irqrestore(&host->lock, flags);
> +}
> +
> +static void sdhci_disable_preset_value(struct sdhci_host *host)
> +{
> +	u16 ctrl;
> +
> +	/* Only for Host Controller version >= v3.00 */
> +	if (host->version < SDHCI_SPEC_300)
> +		return;
> +
> +	ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
> +	ctrl &= ~SDHCI_CTRL_PRESET_VAL_ENABLE;
> +	sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
> +}
> +
>  static const struct mmc_host_ops sdhci_ops = {
>  	.request	= sdhci_request,
>  	.set_ios	= sdhci_set_ios,
> @@ -1610,6 +1644,7 @@ static const struct mmc_host_ops sdhci_ops = {
>  	.start_signal_voltage_switch	=
> sdhci_start_signal_voltage_switch,
>  	.get_max_current_180		= sdhci_get_max_current_180,
>  	.execute_tuning			= sdhci_execute_tuning,
> +	.enable_preset_value		= sdhci_enable_preset_value,
>  };
> 
> 
> /**********************************************************************
> *******\
> @@ -1920,6 +1955,7 @@ static irqreturn_t sdhci_irq(int irq, void
> *dev_id)
>  		sdhci_writel(host, intmask & (SDHCI_INT_CARD_INSERT |
>  			SDHCI_INT_CARD_REMOVE), SDHCI_INT_STATUS);
>  		tasklet_schedule(&host->card_tasklet);
> +		sdhci_disable_preset_value(host);
>  	}
> 
>  	intmask &= ~(SDHCI_INT_CARD_INSERT | SDHCI_INT_CARD_REMOVE);
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index 651e40b..e63e063 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -130,6 +130,7 @@ struct mmc_host_ops {
>  	int	(*start_signal_voltage_switch)(struct mmc_host *host);
>  	int	(*get_max_current_180)(struct mmc_host *mmc);
>  	void	(*execute_tuning)(struct mmc_host *host);
> +	void	(*enable_preset_value)(struct mmc_host *host);
>  };
> 
>  struct mmc_card;
> --
> 1.7.1
> 
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