Re: [PATCH v2 1/3] mmc: core: Add mmc_regulator_set_vqmmc()
From: Andrew Bresticker
Date: Mon Dec 15 2014 - 18:42:30 EST
On Mon, Dec 15, 2014 at 3:25 PM, Doug Anderson <dianders@xxxxxxxxxxxx> wrote:
> This adds logic to the MMC core to set VQMMC. This is expected to be
> called by MMC drivers like dw_mmc as part of (or instead of) their
> start_signal_voltage_switch() callback.
> A few notes:
> * When setting the signal voltage to 3.3V we do our best to make VQMMC
> and VMMC match. It's been reported that this makes some old cards
> happy since they were tested back in the day before UHS when VQMMC
> and VMMC were provided by the same regulator. A nice side effect of
> this is that we don't end up on the hairy edge of VQMMC (2.7V),
> which some EEs claim is a little too close to the minimum for
> * When setting the signal voltage to 1.8V or 1.2V we aim for that
> specific voltage instead of picking the lowest one in the range.
> * We very purposely don't print errors in mmc_regulator_set_vqmmc().
> There are cases where the MMC core will try several different
> voltages and we don't want to pollute the logs.
> Signed-off-by: Doug Anderson <dianders@xxxxxxxxxxxx>
Looks good to me.
Reviewed-by: Andrew Bresticker <abrestic@xxxxxxxxxxxx>
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