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 0C37AEB64D7 for ; Tue, 20 Jun 2023 09:41:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231922AbjFTJln (ORCPT ); Tue, 20 Jun 2023 05:41:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53512 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231899AbjFTJlm (ORCPT ); Tue, 20 Jun 2023 05:41:42 -0400 Received: from mail.zeus03.de (www.zeus03.de [194.117.254.33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 47E19F1 for ; Tue, 20 Jun 2023 02:41:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple; d=sang-engineering.com; h= date:from:to:cc:subject:message-id:references:mime-version :content-type:in-reply-to; s=k1; bh=tfMpnnW+3guYPzLCJJ8Mv1jIbr4E bescqvJbvy3K258=; b=vTzTY9y2y1t3QEQl87oUYGiJc/omQ4j0dEIYhUMQUDo0 r7izDzZBGAC5P/9pbRh/sgyreONoKIuonUgfwWtBTZItLaLfY/bULHYz0X9QXQad 6DgidPwBltDuEBxX9tnP62I901rgByGlBxoGlw73/u/B/Nc/cyi1TxvRI3Y5Gys= Received: (qmail 582700 invoked from network); 20 Jun 2023 11:41:39 +0200 Received: by mail.zeus03.de with ESMTPSA (TLS_AES_256_GCM_SHA384 encrypted, authenticated); 20 Jun 2023 11:41:39 +0200 X-UD-Smtp-Session: l3s3148p1@mvY8dYz+WpdehhtC Date: Tue, 20 Jun 2023 11:41:39 +0200 From: Wolfram Sang To: Johan Hovold Cc: linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH 4/5] gnss: ubx: add support for the reset gpio Message-ID: Mail-Followup-To: Wolfram Sang , Johan Hovold , linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org References: <20230523064310.3005-1-wsa+renesas@sang-engineering.com> <20230523064310.3005-5-wsa+renesas@sang-engineering.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="TA9zqrB6i6FlXnUD" Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-renesas-soc@vger.kernel.org --TA9zqrB6i6FlXnUD Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > But can you elaborate on the "disappearing" bit? How exactly does it > "disappear" when the gnss0 device is *not* opened? When you send an I2C message with the address of the device, it usually ACKs it to say "Hi, I am here". When the ublox device is in reset state, it does not ACK its address. So, tools like "i2cdetect" will not report the device as "someone is listening there". Here is the i2cdetect output with the GNSS device open: # i2cdetect -y -r 15 0 1 2 3 4 5 6 7 8 9 a b c d e f 00: -- -- -- -- -- -- -- --=20 10: 10 -- -- -- -- -- -- -- -- -- -- -- -- 1d -- --=20 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --=20 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --=20 40: -- -- 42 -- -- -- -- -- -- -- -- -- -- -- -- UU=20 50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --=20 60: -- -- -- -- -- -- -- -- -- -- -- 6b -- -- -- --=20 70: -- UU -- -- UU UU -- -- =20 And with the device closed. Note address 0x42 disappearing: # i2cdetect -y -r 15 0 1 2 3 4 5 6 7 8 9 a b c d e f 00: -- -- -- -- -- -- -- --=20 10: 10 -- -- -- -- -- -- -- -- -- -- -- -- 1d -- --=20 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --=20 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --=20 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- UU=20 50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --=20 60: -- -- -- -- -- -- -- -- -- -- -- 6b -- -- -- --=20 70: -- UU -- -- UU UU -- -- =20 --TA9zqrB6i6FlXnUD Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEOZGx6rniZ1Gk92RdFA3kzBSgKbYFAmSRdE8ACgkQFA3kzBSg KbarfA/+On0rLpkEJ+z3vMEgM7eJICiUy+MeY3d/u7A2Ryur9LhIFz8UmqJYxovG kTk7Au9WjjnkGKmpNi3lLT0TQEp7HipluRrlKo/uwnedeI2KMrb00qEh1rQUDPn9 Lhj1Q0OhvmrmKEBvypihc47r2ePPPzTNk2HCqhtW3uIBg369zkwKoqudDTPBHw8q SxJbb92mtUAssqh8rjiqzEQvEwr2y8xYDO30VHJefzWIuazUM4TCwN8OqtSHp+0y VyVvmG1pSjjDZuAFT13VpmI6/6hABlivVWQT70U4ShnUIL1hBo8ePBF/ehwKa7RH P+VayQ3eFzGx60IyDPTNJ+hDxwWRXVsNotO472cs3fmg/Nobvs/dN85us4oA61AR cHZ8CkjQOdwP6w/jsOxg/uZjyoNqANckC1jq848eoCk9nNNgO8G74nG/RYBIH9uA phpMlgTv5UcHvD6MyN1Vh431SpapYUVdleiMasd/cjP4yq8rKJbrAWI4JKcYpa4y Qpd+im6XPS0TNZhQQehYFJJJ5aZyCSeVD2cG+SQxKGWCYD1Ce0ZOwSYU3cLNhZIM Vf5J2zXps5PwGlCjr129Ut+vOfkmDdANiFWxnxALqZjDY0sAhGAritm2XvgXiV3s BZIMhNQSz0NdW/2FS6YQQnP1cQrGWBGlVu/gev9JLw7wrGtCNSw= =8voC -----END PGP SIGNATURE----- --TA9zqrB6i6FlXnUD--