From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Brown Subject: Re: [PATCH v3 1/2] regulator: dt-bindings: add QCOM RPMh regulator bindings Date: Wed, 30 May 2018 17:59:37 +0100 Message-ID: <20180530165937.GX6920@sirena.org.uk> References: <20180530150241.GO6920@sirena.org.uk> <20180530154849.GQ6920@sirena.org.uk> <20180530160744.GS6920@sirena.org.uk> <20180530161311.GT6920@sirena.org.uk> <20180530163644.GW6920@sirena.org.uk> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="1RhGCd1AsoFHGRHc" Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Doug Anderson Cc: David Collins , Liam Girdwood , Rob Herring , Mark Rutland , linux-arm-msm@vger.kernel.org, Linux ARM , devicetree@vger.kernel.org, LKML , Rajendra Nayak , Stephen Boyd List-Id: linux-arm-msm@vger.kernel.org --1RhGCd1AsoFHGRHc Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Wed, May 30, 2018 at 09:41:55AM -0700, Doug Anderson wrote: > On Wed, May 30, 2018 at 9:36 AM, Mark Brown wrote: > > Yeah, and I don't think that's unreasonable for the core to do - just > > drop the voltage to the constraint minimum after it has turned off the > > regulator, then recheck and raise if needed before it enables again. > Would it do this for all regulators, though? Most regulators are > hooked up over a slow i2c bus, so that means that every regulator > disable would now do an extra i2c transfer even though for all > regulators (other than RPMh) the voltage of a regulator doesn't matter > when it's been "disabled' (from Linux's point of view). It'd only affect regulators that can vary in voltage and actually get disabled which is a pretty small subset. Most regulators are either fixed voltage or always on. > Hrmmm, I suppose maybe it'd be OK though because for most regulators > we'd use "regcache" and most regulators that we enabled/disable a lot > are not expected to change voltage in Linux (so the regcache write > would hopefully be a noop), so maybe it wouldn't be _that_ > inefficient... Even if the regulator lacks a cache we'd at least skip out on the write when we're not changing voltage as we'd do a read/modify/update cycle and stop at the modify. --1RhGCd1AsoFHGRHc Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAlsO2HkACgkQJNaLcl1U h9DTXQf/VgwB1seFzCThTskB5IXfv81dOdpaoeVGDg7V4Y/r6nAbB5uNeRkQojgl aMDgpQFnVqVBsZXktBllwQ7foPOGg8WSd0Q4IlVuQwNNf5nAFqSFy+huw0o47LJ8 x7aWjVFpLTA4XuNezN6XXwNcP2QO6ZY7lKQmXko66py8oQ7KKrktaTaG6mRXAkwf Jb/i+lr13F6TFcb71Ky4gMEx6rClG12dMIs8a7Ud/USTmibRTQZ7uEX+mG1hRfHC nsiHZ9YV+OCpIuSePcDwSzRL2CxU//EK4CLx3+Ztp2BCd7XQLk3hsO+arIuOHthH A/Zc69LtGG1ZIhBnZtGW4XjsKCOr2g== =ZaJS -----END PGP SIGNATURE----- --1RhGCd1AsoFHGRHc--