From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752272AbdJTIYd (ORCPT ); Fri, 20 Oct 2017 04:24:33 -0400 Received: from out4-smtp.messagingengine.com ([66.111.4.28]:37871 "EHLO out4-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752090AbdJTIY1 (ORCPT ); Fri, 20 Oct 2017 04:24:27 -0400 X-ME-Sender: Message-ID: <1508487855.24322.49.camel@aj.id.au> Subject: Re: [RFC PATCH 1/5] gpio: gpiolib: Add core support for maintaining GPIO values on reset From: Andrew Jeffery To: Linus Walleij Cc: "linux-gpio@vger.kernel.org" , Jonathan Corbet , Joel Stanley , Ryan Chen , Rob Herring , Frank Rowand , Charles Keepax , Laxman Dewangan , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , patches@opensource.cirrus.com, "devicetree@vger.kernel.org" , OpenBMC Maillist , linux-aspeed@lists.ozlabs.org Date: Fri, 20 Oct 2017 18:54:15 +1030 In-Reply-To: References: <20171020033727.21557-1-andrew@aj.id.au> <20171020033727.21557-2-andrew@aj.id.au> Content-Type: multipart/signed; micalg="pgp-sha512"; protocol="application/pgp-signature"; boundary="=-d48CUOoV9VuoK6rPhecQ" X-Mailer: Evolution 3.22.6-1ubuntu1 Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-d48CUOoV9VuoK6rPhecQ Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, 2017-10-20 at 09:17 +0200, Linus Walleij wrote: > > On Fri, Oct 20, 2017 at 5:37 AM, Andrew Jeffery wrote= : >=C2=A0 > > GPIO state reset tolerance is implemented in gpiolib through the > > addition of a new pinconf parameter. With that, some renaming of helper= s > > is done to clarify the scope of the already existing > > gpiochip_line_is_persistent(), as it's now ambiguous as to whether that > > means on suspend, reset or both. >=C2=A0 > Isn't it most reasonable to say persistance covers both cases, reset > and/or sleep? This seems a bit like overdefined. I definitely had some internal debate about that. I erred on the side of avoiding potential change in expectations for the arizona. If you consider = that overdefined then I'm happy to go the other way. >=C2=A0 > So can we say that is this flag is set, the hardware and driver should > do its best to preserve the value across any system disruptions. >=C2=A0 > We can change the wording of course, patches welcome for that. Yep. >=C2=A0 > But do we really need to distinguish the cases of disruption and > whether we cover up for them or not? >=C2=A0 > I would say we can deal with that the day we have a system with > two register bits (or similar) where you can select to preserve across > sleep, reset, one or the other, AND there is also a usecase such that > a user wants to preserve the value across reset but not suspend or > vice versa. >=C2=A0 > I suspect that will not happen. A very reasonable approach. Cheers for the feedback. Andrew --=-d48CUOoV9VuoK6rPhecQ Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQIcBAABCgAGBQJZ6bKvAAoJEJ0dnzgO5LT5xb0P/3hJ2tqH7oYshUwTVEJjSLd2 xjGVSS5Vqrmn7FwEwmk1lYUlNSERaM1NtKwGKCVSM6Xvf+3MJ5TuXvxJRCHiSAxC qNerc80lrTZKuVNOwlfv3YCPZj5MHiNwynWaUoPuSIc0Y7iIWoYQl3oI5IhVVjQM f+v+QHSEa26NYwT8LJIpOmfKgwzypl1g6oTELB3g+Bt3Ff49Smr5VzCvborOFBNs W/qBybuf1qaKs/dv2hGLKpEULhVP+Y2L6zEL2zMd3URGlAvtCxBv3OsJMfHyQLDh cac0ciSAepA+SxsDu1fXHzrQ2X0A/62MpCsgVY97fjaU7yXGLjZ4hgbIrN6HAPAg s4c/PYjJZxkD1a1KhEumify8dpLXbVFLDv678/v6kc2MdeuETq0LZWo4tJ4JY/UA Vk3J0Q0Uf3T+P5+5ZI2ZgSAbfJL0JE9ngshPjA65eWP6UTvIuq/KmMZKxmd2nRv4 DGrfzQONzTU7sbezF7oUOF78FejXU15Qc4YEifkSph9VLgUMpLa3BpJXRRUxhy00 8a/fxb7qDjU/H4eB7fYgPVsXzxIn2l03vVzAX8VMGSxEsjerrqUn2EF3NKj669xD XSbBDvaeqyGF0FiC3jH9sLZYREKno/Jigh5D3xyO5lLTbyLWrh4V648cnn/0dMEl w47nA2cEGma8s58k+HHT =8Vaa -----END PGP SIGNATURE----- --=-d48CUOoV9VuoK6rPhecQ--