From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 06E7AC4167B for ; Mon, 6 Nov 2023 14:18:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230009AbjKFOSk (ORCPT ); Mon, 6 Nov 2023 09:18:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49734 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229485AbjKFOSj (ORCPT ); Mon, 6 Nov 2023 09:18:39 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DF452BB; Mon, 6 Nov 2023 06:18:36 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8A3E5C433C9; Mon, 6 Nov 2023 14:18:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1699280316; bh=u8svhs0OTz5m3eqVl0RH5Bqa1jew0U6A6zJ0pPCqAbU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=oeEOcEYy4AKuikIhbFmIe9zY4l8Y2Z/ygsBFJyULM1V8Lu/Xgc1NbPlc9CYmy8AFw KBp8zz/P2ZBHTGR5hP2U4UAwWFQo2zjayyritV8exdFIUS5DVfQigm8EOGM/nCF1Tk qRB90XgEq68w0bvOSqTcJPqHLuNwvxo83ztX1zAO0pVh3/Rtqny6UGJVC6n1LXAX7V mha/BkxhB3jeFW0nnYaLKkFi6Pp4oo/z0fqhoNJQQhcUzFKc4sdkisAJ5lW5iWMCzr 4eje0uMQy/5jBDuvFIe62GgbcEJUPsPP0mkmgPoERoRaHzGHpdE5MXsZj8dzkY51jW dzdzD7eMBLy3w== Received: from johan by xi.lan with local (Exim 4.96) (envelope-from ) id 1r00Rm-0000MC-1Y; Mon, 06 Nov 2023 15:19:22 +0100 Date: Mon, 6 Nov 2023 15:19:22 +0100 From: Johan Hovold To: Wolfram Sang Cc: linux-renesas-soc@vger.kernel.org, Geert Uytterhoeven , linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 3/3] gnss: ubx: add support for the reset gpio Message-ID: References: <20230921133202.5828-1-wsa+renesas@sang-engineering.com> <20230921133202.5828-4-wsa+renesas@sang-engineering.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="2TOfkmwbPXlIz3N9" Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --2TOfkmwbPXlIz3N9 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Oct 23, 2023 at 09:09:03AM +0200, Wolfram Sang wrote: > > So this means that the reset line will be asserted indefinitely in case > > the GNSS receiver is not used. Are you sure that's a good idea? >=20 > Yup. Saves power. We do this for our ethernet PHYs as well. Any reasons > not to do this? AFAIK you should generally not try to use reset this way as you may end up leaking current (and possibly other complications). =20 > > I don't know yet which module this is for, or how this signal is > > supposed to be used, but the above makes this look more like an > > active-high (regulator) enable signal. Perhaps that's what it is or > > should be modelled as (i.e. as a fixed regulator). >=20 > Nope, it is a RESET_N pin. And the neo-m8 hardware integration manual explicitly says that it shall not be used as a disable signal: 1.5 I/O pins RESET_N: Reset input Driving RESET_N low activates a hardware reset of the system. Use this pin only to reset the module. Do not use RESET_N to turn the module on and off, since the reset state increases power consumption. Some of the other modules in this family says so explicitly also in the datasheet. Johan --2TOfkmwbPXlIz3N9 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQQHbPq+cpGvN/peuzMLxc3C7H1lCAUCZUj15gAKCRALxc3C7H1l CJIwAQCUyRJ2dOra5odtunrzTEfmSEGT8aqQKG1u1/YOvdgjWgD/d4i5DubnOWFW dGzRIgQl92TRBa3jBbCYWLFr0uqHdQ0= =Z+gS -----END PGP SIGNATURE----- --2TOfkmwbPXlIz3N9--