[PATCH 1/3] mmc: dw_mmc: use mmc_regulator_get_supply to handle regulators

[Doug Anderson]

Seungwon,

On Thu, Jun 26, 2014 at 3:30 AM, Seungwon Jeon <tgih.jun at samsung.com> wrote:
> Hi Doug,
>
> On Thu, June 26, 2014, Doug Anderson wrote:
>> Seungwon,
>>
>> On Wed, Jun 25, 2014 at 4:18 AM, Seungwon Jeon <tgih.jun at samsung.com> wrote:
>> >> >> +       case MMC_POWER_ON:
>> >> >> +               if (!IS_ERR(mmc->supply.vqmmc) &&
>> >> >> +                               !test_bit(DW_MMC_IO_POWERED, &slot->flags)) {
>> > You can use regulator_is_enabled() instead of flag bit, DW_MMC_IO_POWERED.
>>
>> I'd be a little worried about regulator_is_enabled() since regulators
>> are reference counted.  What if someone else is sharing this
>> regulator?  The regulator might happen to be enabled when you check it
>> but unless you add your own dw_mmc reference count they might turn it
>> off.
> Cool, that's a possibility. Some assumption may need.
> If mmc's core can guarantee its balance, I think we don't need to consider some flag.

I notice that the mmc core seems to keep a flag itself for vdd (the
mmc->regulator_enabled flag).  That would imply that the core thought
it was important to have the extra flag and that we should keep our
own flag for vqmmc.

-Doug