linux-kernel - Re: Question about "regulator: core: Only count load for enabled consumers" in -next

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Date:   Mon, 26 Nov 2018 17:59:45 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Doug Anderson <dianders@...omium.org>
Cc:     masneyb@...tation.org, Liam Girdwood <lgirdwood@...il.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: Question about "regulator: core: Only count load for enabled
 consumers" in -next

On Mon, Nov 26, 2018 at 09:43:42AM -0800, Doug Anderson wrote:

> NOTE: another option would be to change the regulator driver to just
> force this rail to a high power mode and never let it change.  That's
> what we're doing on a SDM845-based board.  When the regulator is off
> the mode doesn't matter and as per the above argument we always want
> it in high power mode when it's on.

You should never need to modify the driver for this, the regulator
framework will only change things if it's been given permission to do
so - simply don't specify a regulator-allowed-modes property and the
mode will be left alone (we should probably still use -initial-mode if
it's specified but I'd need to check if we actually do).

> > I see that there are 8 users of regulator-system-load but most are all
> > addressing this same issue with the SD card.
> > qcom-msm8974-sony-xperia-castor.dts sets the load to 500 mA but all of
> > the other msm8974-based SOCs use 200 mA. I'm not sure if this is
> > correct.

> Interestingly enough I think the max load here is specified by the SD
> card specification.  My quick reading of the SD spec shows that you
> could do all sorts of complex negotiation with the card about how much
> load it could take up but Linux didn't actually support that.  If I'm
> reading it right the default is 200 mA.

I'd like to see how closely hardware adheres to the spec too...

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