linux-kernel - Re: [PATCH 3/3] mmc: sdhci: check voltage range only on regulators aware of voltage value

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Date:	Tue, 4 Dec 2012 22:50:03 +0800
From:	Kevin Liu <keyuan.liu@...il.com>
To:	Marek Szyprowski <m.szyprowski@...sung.com>
Cc:	linux-kernel@...r.kernel.org, linux-mmc@...r.kernel.org,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Liam Girdwood <lrg@...com>, Chris Ball <cjb@...top.org>
Subject: Re: [PATCH 3/3] mmc: sdhci: check voltage range only on regulators
 aware of voltage value

2012/12/4 Marek Szyprowski <m.szyprowski@...sung.com>:
> Some regulators don't report any voltage values, so checking supported
> voltage range results in disabling all SDHCI_CAN_VDD_* flags and
> registration failure. This patch finally provides a correct fix for the
> registration of SDHCI driver with all possible voltage regulators:
> dummy, fixed and regulated without using regulator_count_voltages()
> hacks.
>
> Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
> ---
>  drivers/mmc/host/sdhci.c |    6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index a9ad2cd..d244dc0 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -2930,7 +2930,11 @@ int sdhci_add_host(struct sdhci_host *host)
>         }
>
>  #ifdef CONFIG_REGULATOR
> -       if (host->vmmc && regulator_count_voltages(host->vmmc) > 1) {
> +       /*
> +        * Voltage range check makes sense only if regulator reports
> +        * any voltage value.
> +        */
> +       if (host->vmmc && regulator_get_voltage(host->vmmc) > 0) {
>                 ret = regulator_is_supported_voltage(host->vmmc, 2700000,
>                         3600000);
>                 if ((ret <= 0) || (!(caps[0] & SDHCI_CAN_VDD_330)))

Good idea. But how about the regulator is disabled at this point? So I
suggest to change to
     if (host->vmmc && regulator_get_voltage(host->vmmc) >= 0)

Thanks
Kevin
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