[RESEND PATCH v2 4/4] mmc: sdhci-of-arasan: add sdhci_arasan_voltage_switch for arasan,5.1

[Adrian Hunter]

On 23/09/16 03:12, Shawn Lin wrote:
> Per the vendor's requirement, we shouldn't do any setting for
> 1.8V Signaling Enable, otherwise the interaction/behaviour between
> phy and controller will be undefined. Mostly it works fine if we do
> that, but we still see failures. Anyway, let's fix it to meet the
> vendor's requirement. The error log looks like:
> 
>  [   93.405085] mmc1: unexpected status 0x800900 after switch
>  [   93.408474] mmc1: switch to bus width 1 failed
>  [   93.408482] mmc1: mmc_select_hs200 failed, error -110
>  [   93.408492] mmc1: error -110 during resume (card was removed?)
>  [   93.408705] PM: resume of devices complete after 213.453 msecs
> 
> Signed-off-by: Shawn Lin <shawn.lin at rock-chips.com>

Acked-by: Adrian Hunter <adrian.hunter at intel.com>

> ---
> 
> Changes in v2: None
> 
>  drivers/mmc/host/sdhci-of-arasan.c | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-of-arasan.c b/drivers/mmc/host/sdhci-of-arasan.c
> index da8e40a..1573a8d 100644
> --- a/drivers/mmc/host/sdhci-of-arasan.c
> +++ b/drivers/mmc/host/sdhci-of-arasan.c
> @@ -265,6 +265,28 @@ void sdhci_arasan_reset(struct sdhci_host *host, u8 mask)
>  	}
>  }
>  
> +static int sdhci_arasan_voltage_switch(struct mmc_host *mmc,
> +				       struct mmc_ios *ios)
> +{
> +	switch (ios->signal_voltage) {
> +	case MMC_SIGNAL_VOLTAGE_180:
> +		/*
> +		 * Plese don't switch to 1V8 as arasan,5.1 doesn't
> +		 * actually refer to this setting to indicate the
> +		 * signal voltage and the state machine will be broken
> +		 * actually if we force to enable 1V8. That's something
> +		 * like broken quirk but we could work around here.
> +		 */
> +		return 0;
> +	case MMC_SIGNAL_VOLTAGE_330:
> +	case MMC_SIGNAL_VOLTAGE_120:
> +		/* We don't support 3V3 and 1V2 */
> +		break;
> +	}
> +
> +	return -EINVAL;
> +}
> +
>  static struct sdhci_ops sdhci_arasan_ops = {
>  	.set_clock = sdhci_arasan_set_clock,
>  	.get_max_clock = sdhci_pltfm_clk_get_max_clock,
> @@ -661,6 +683,8 @@ static int sdhci_arasan_probe(struct platform_device *pdev)
>  
>  		host->mmc_host_ops.hs400_enhanced_strobe =
>  					sdhci_arasan_hs400_enhanced_strobe;
> +		host->mmc_host_ops.start_signal_voltage_switch =
> +					sdhci_arasan_voltage_switch;
>  	}
>  
>  	ret = sdhci_add_host(host);
>