Re: [PATCH v2 2/3] mmc: dw_mmc: Use mmc_regulator_set_vqmmc in start_signal_voltage_switch

From: Doug Anderson
Date: Mon Dec 15 2014 - 19:09:12 EST


On Mon, Dec 15, 2014 at 3:44 PM, Andrew Bresticker
<abrestic@xxxxxxxxxxxx> wrote:
>> - if (!IS_ERR(mmc->supply.vqmmc)) {
>> - ret = regulator_set_voltage(mmc->supply.vqmmc, min_uv, max_uv);
>> -
>> - if (ret) {
>> - dev_dbg(&mmc->class_dev,
>> - "Regulator set error %d: %d - %d\n",
>> - ret, min_uv, max_uv);
>> - return ret;
>> - }
>> - }
>> + mmc_regulator_set_vqmmc(mmc, ios);
> Shouldn't we check the return value here and bail out of the voltage
> switch procedure if it fails?

My thought was to purposely _not_ check the return value. The comment
right above this says:

* Program the voltage. Note that some instances of dw_mmc may use
* the UHS_REG for this. For other instances (like exynos) the UHS_REG
* does no harm but you need to set the regulator directly. Try both.

...I'm not 100% sure that I understand how the UHS_REG is supposed to
be implemented since I've never seen a system that uses it. I was
assuming that if you have UHS_REG you don't need the regulator...

...but probably a better solution is to return the error if "
!IS_ERR(mmc->supply.vqmmc)". Let me fix that up and repost.

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