From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759475Ab0D3TNA (ORCPT ); Fri, 30 Apr 2010 15:13:00 -0400 Received: from fg-out-1718.google.com ([72.14.220.154]:22832 "EHLO fg-out-1718.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932510Ab0D3Q6o (ORCPT ); Fri, 30 Apr 2010 12:58:44 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=emrwgUjmPZRzNqFhVmiyLPyO5jvymNB9LyEn9mK2u3YPT0c58nQfextOyapx+gz4W6 GdI4GoLt8KmAxIt0z1+IsRqWYM2jzovTwZ5e5xLe7jEecekSaN8JoVoYh/rVXaZxa7JD K5r1kfrNXVgVI0T3Htw/Xeq3aiR1AANQ04K54= Date: Fri, 30 Apr 2010 13:07:09 +0300 From: Sergey Senozhatsky To: Jean Delvare Cc: "Ben Dooks (embedded platforms)" , Wolfram Sang , linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: i2c-i801 retries on lost arbitration (resent: no gpg) Message-ID: <20100430100709.GD3553@swordfish.minsk.epam.com> References: <20100430094412.GC3553@swordfish.minsk.epam.com> <20100430114822.1a5e0cf9@hyperion.delvare> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="PuGuTyElPB9bOcsM" Content-Disposition: inline In-Reply-To: <20100430114822.1a5e0cf9@hyperion.delvare> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --PuGuTyElPB9bOcsM Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On (04/30/10 11:48), Jean Delvare wrote: > Hi Sergey, >=20 >=20 > > Both i2c spec and ICH7 datasheet requires to restart transaction in > > case of lost arbitration. > >=20 > > "No information is lost during the arbitration process. A master that > > loses the arbitration can generate clock pulses until the end of the > > byte in which it loses the arbitration and must restart its transaction > > when the bus is idle." > > =20 > > Please see the following patch. Is it correct? >=20 > No, it's not. As you wrote above, this is not specific to the Intel ICH > but a general I2C issue. As such it must be handled in i2c-core and not > by individual drivers. And as a matter of fact, it is already handled. > Look at functions i2c_transfer and i2c_smbus_xfer in i2c-core.c, see > the comments "Retry automatically on arbitration loss", the code is > already there. It's just a matter of bus drivers properly setting > adapter->retries (which i2c-i801.c does already.) >=20 Thanks. > So I don't know which kernel you're using, but with the latest upstream > kernel, things should work just fine already. >=20 OK. Thanks a lot. Sergey =09 --PuGuTyElPB9bOcsM Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) iJwEAQECAAYFAkvaq80ACgkQfKHnntdSXjSDfwP+OpAlzT7Ze0a9uxTb8YQlpEno YKSK6agneTDAcvRp14lQ/Z7fIp8OXOjeacZ9aiCLcG8HqXSzBssDU6g6Th90B6HT l392L6UgKh/Ipa0sDM1dozoj7TQwOfzCEqwB8p3YhrtdG1SAknaexm0TkBpqR0BE p6jXt936g1C9I1RgoyE= =vLWa -----END PGP SIGNATURE----- --PuGuTyElPB9bOcsM--