Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755999AbdGCPH4 (ORCPT ); Mon, 3 Jul 2017 11:07:56 -0400 Received: from mezzanine.sirena.org.uk ([106.187.55.193]:45480 "EHLO mezzanine.sirena.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755291AbdGCPHu (ORCPT ); Mon, 3 Jul 2017 11:07:50 -0400 Date: Mon, 3 Jul 2017 16:07:33 +0100 From: Mark Brown To: Viresh Kumar Cc: Chen-Yu Tsai , "Enrico Weigelt, metux IT consult" , Rafael Wysocki , Vincent Guittot , Rob Herring , Greg Kroah-Hartman , Stephen Boyd , linux-kernel , rnayak@codeaurora.org, Shiraz Hashim , linux-arm-kernel Message-ID: <20170703150733.sop6yrrpfl3ne32g@sirena.org.uk> References: <20170630035533.GV29665@vireshk-i7> <20170630041211.GX29665@vireshk-i7> <20170630051203.GY29665@vireshk-i7> <20170630084330.GB29665@vireshk-i7> <20170630121026.azppihjqls5i6bbr@sirena.org.uk> <20170703061552.GB3532@vireshk-i7> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="michtqixeweh6x76" Content-Disposition: inline In-Reply-To: <20170703061552.GB3532@vireshk-i7> X-Cookie: Now, let's SEND OUT for QUICHE!! User-Agent: NeoMutt/20170306 (1.8.0) X-SA-Exim-Connect-IP: 2001:470:1f1d:6b5::3 X-SA-Exim-Mail-From: broonie@sirena.org.uk Subject: Re: [RFC 0/5] drivers: Add boot constraints core X-SA-Exim-Version: 4.2.1 (built Tue, 02 Aug 2016 21:08:31 +0000) X-SA-Exim-Scanned: No (on mezzanine.sirena.org.uk); Unknown failure Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2063 Lines: 56 --michtqixeweh6x76 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Mon, Jul 03, 2017 at 11:45:52AM +0530, Viresh Kumar wrote: > On 30-06-17, 13:10, Mark Brown wrote: > > On Fri, Jun 30, 2017 at 02:13:30PM +0530, Viresh Kumar wrote: > > > On 30-06-17, 14:36, Chen-Yu Tsai wrote: > > > And so the DT node shall have this: > > > regulator-min-microvolt = <1800000>; > > > regulator-max-microvolt = <3000000>; > > > Isn't it ? > > If the DMA can't tolerate more than 2.5V then why would the constraints > > allow the voltage to float that far? Similarly on the low end? > The above regulator-min/max-microvolt values I mentioned were for the regulator > device and not what the consumers would request. Yes, DMA will request something If you're putting the maximum possible range that the physical regulator can supply into machine constraints then you really haven't understood what machine constraints are at all. > > Please remember that devices shouldn't be managing their voltages unless > > they are actively changing them at runtime, simply setting them at > > startup is the job of the constraints. I would be very surprised to see > > a DMA controller doing anything like DVFS. > Sure, DMA would most likely set a constraint from probe. Maybe I could have used No, it really shouldn't. Please read what I wrote. > MMC in the above example, which may actually do DVFS at runtime. Yes, MMC does vary voltage. --michtqixeweh6x76 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCAAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAllaXbUACgkQJNaLcl1U h9AnxQf7BbPOlboG+J4Dk+qxS1mV8YVQLH8U7DuA7adsRmpyKv7qIXnbNXF3LKqZ R1GYKNFyAyjFOBxxDfZ7xt5IQM8LhGL33Yyja9Gi935BlM6PANxKRcoQ2QFyMW54 +3QhA6f2VmXYeJNXyjOyRBIYWDSJ8mT7a8RiaVQ29Y7Ab76FlrcUlHKBYqt00z+H fQxXoFgEenwT4n1Z/wKAzjZHA+lIz9ncyQ3JqQhP+Dlw2atEdKqPf37IqjK6ceB9 9PGebEnrCyUSAo6BY2CqQb1pGzFjbFXuHPJjw8QoxyM0t5PEQmVooZXXTFFdQc+F r5+Sx8TLtJy0YVps6b9Nwcc1kEjo1Q== =4vyI -----END PGP SIGNATURE----- --michtqixeweh6x76--