linux-kernel - Re: [PATCH 1/1] regulators: bd718x7: Add enable times

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Message-ID: <3f37c66f00878e8bc6a387d2969bde32cf2f5fbb.camel@fi.rohmeurope.com>
Date:   Wed, 16 Dec 2020 17:47:11 +0000
From:   "Vaittinen, Matti" <Matti.Vaittinen@...rohmeurope.com>
To:     "broonie@...nel.org" <broonie@...nel.org>,
        "guido.gunther@...i.sm" <guido.gunther@...i.sm>
CC:     "lgirdwood@...il.com" <lgirdwood@...il.com>,
        linux-power <linux-power@...rohmeurope.com>,
        "angus.ainslie@...i.sm" <angus.ainslie@...i.sm>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/1] regulators: bd718x7: Add enable times


On Wed, 2020-12-16 at 12:48 +0000, Mark Brown wrote:
> On Wed, Dec 16, 2020 at 01:41:33PM +0100, Guido Günther wrote:
> > On Wed, Dec 16, 2020 at 12:29:20PM +0000, Vaittinen, Matti wrote:
> > > > +			.enable_time = 144,
> > > Where are these values obtained from? I have a feeling they might
> > > be
> > > board / load specific. If this is the case - can the "regulator-
> > > enable-
> > > ramp-delay" from device-tree be used instead to avoid hard-coding 
> > > board
> > > specific values in the driver? Although, sane defaults would
> > > probably
> > > not be a bad idea - if I read code correctly then the constrains
> > > from
> > > DT can be used to override these values.
> > They're the 'typical values' from the data sheet and it's basically
> > all
> > about setting a default for "regulator-enable-ramp-delay" to avoid
> > having every board do the same. If that's not the right thing todo
> > let
> > me know and i add these to each of our boards (which is where i
> > basically started from but then figured that this would be busywork
> > and every board would hit that problem).
> 
> If it's a DCDC they're *probably* generic values rather than board
> specific, they tend to be more predictable as they're regulating much
> more actively than LDOs.

Thank you for explanation Mark & Guido.
Then I'd say the 'default' enable times do make sense. Thanks for
improving the driver!

Best Regards
	Matti Vaittinen