Re: [PATCH v2 1/5] mmc: host: sdhci-s3c: Add broken-voltage DT property for broken voltage quirk

[Jaehoon Chung <jh80.chung@samsung.com>]

On 09/19/2012 11:39 PM, Chris Ball wrote:
> Hi,
> 
> On Wed, Sep 19 2012, Jaehoon Chung wrote:
>>> On Wed, Sep 19 2012, Tomasz Figa wrote:
>>>> We could just check if the regulator provides the capability to change the 
>>>> voltage.
>>>>
>>>> I don't see any direct way of querying the regulator for provided 
>>>> capabilities (correct me if I'm just blind), but calling 
>>>> regulator_count_voltages() on the regulator and checking if the returned 
>>>> value is 1 should be enough to assume that the regulator is fixed.
>>>
>>> Sounds good, I agree.  Are you able to test that the obvious patch below
>>> works on your fixed-regulator board?
>>>
>>> Jaehoon and Adrian, can you think of any reason why we shouldn't replace
>>> MMC_CAP2_BROKEN_VOLTAGE with the regulator_count_voltages() call below?
>>> Thanks.
>>
>> I think this is better than using MMC_CAP2_BROKEN_VOLTAGE.
>> I tested with this..and working fine.
> 
> Great, here's the patch.  Jaehoon, once this is merged, maybe you could
> help remove the uses of MMC_CAP2_BROKEN_VOLTAGE from arch/arm/mach-exynos
> and arch/arm/mach-s5pv210 now that they're no longer needed?
Right, I will remove them and send the patch.

Best Regards,
Jaehoon Chung
> 
> Thanks,
> 
> - Chris.
> 
> 
> Subject: [PATCH] mmc: core: Replace MMC_CAP2_BROKEN_VOLTAGE with test for fixed regulator
> 
> Before this patch, we were using MMC_CAP2_BROKEN_VOLTAGE as a way to
> avoid calling regulator_set_voltage() on a fixed regulator, but that's
> just duplicating information that already exists -- we should test
> whether the regulator is fixed directly, instead of via a capability.
> 
> This patch implements that test.  We can't reclaim the capability bit
> just yet, since there are still boards in arch/arm/ that reference it;
> those references can be removed now.
> 
> Reported-by: Tomasz Figa <t.figa@samsung.com>
> Signed-off-by: Chris Ball <cjb@laptop.org>
> ---
>  drivers/mmc/core/core.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 044cd01..6612163 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -1113,7 +1113,8 @@ int mmc_regulator_set_ocr(struct mmc_host *mmc,
>  		int		tmp;
>  		int		voltage;
>  
> -		/* REVISIT mmc_vddrange_to_ocrmask() may have set some
> +		/*
> +		 * REVISIT mmc_vddrange_to_ocrmask() may have set some
>  		 * bits this regulator doesn't quite support ... don't
>  		 * be too picky, most cards and regulators are OK with
>  		 * a 0.1V range goof (it's a small error percentage).
> @@ -1127,12 +1128,13 @@ int mmc_regulator_set_ocr(struct mmc_host *mmc,
>  			max_uV = min_uV + 100 * 1000;
>  		}
>  
> -		/* avoid needless changes to this voltage; the regulator
> -		 * might not allow this operation
> +		/*
> +		 * If we're using a fixed/static regulator, don't call
> +		 * regulator_set_voltage; it would fail.
>  		 */
>  		voltage = regulator_get_voltage(supply);
>  
> -		if (mmc->caps2 & MMC_CAP2_BROKEN_VOLTAGE)
> +		if (regulator_count_voltages(supply) == 1)
>  			min_uV = max_uV = voltage;
>  
>  		if (voltage < 0)
>