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

[Seungwon Jeon <tgih.jun@samsung.com>]

Hi Doug,

On Thu, June 26, 2014, Doug Anderson wrote:
> Seungwon,
> 
> On Wed, Jun 25, 2014 at 4:18 AM, Seungwon Jeon <tgih.jun@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.

Thanks,
Seungwon Jeon
> 
> > Important thing is that if powering vmmc failed at MMC_POWER_UP, vqmmc should not be powered.
> 
> Good point.
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