Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759940AbYC1NAl (ORCPT ); Fri, 28 Mar 2008 09:00:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758555AbYC1Mzo (ORCPT ); Fri, 28 Mar 2008 08:55:44 -0400 Received: from SpacedOut.fries.net ([67.64.210.234]:34541 "EHLO SpacedOut.fries.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758542AbYC1Mzm (ORCPT ); Fri, 28 Mar 2008 08:55:42 -0400 Date: Fri, 28 Mar 2008 07:26:55 -0500 From: David Fries To: linux-kernel@vger.kernel.org Cc: Evgeniy Polyakov Subject: [PATCH 21/35] W1: w1_io.c reset comments and msleep Message-ID: <20080328122655.GV3613@spacedout.fries.net> References: <200803272343.m2RNhDac017650@SpacedOut.fries.net> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="SidV/bKy1CyabPX8" Content-Disposition: inline In-Reply-To: <200803272343.m2RNhDac017650@SpacedOut.fries.net> User-Agent: Mutt/1.5.4i X-Greylist: Sender is SPF-compliant, not delayed by milter-greylist-3.0 (SpacedOut.fries.net [127.0.0.1]); Fri, 28 Mar 2008 07:26:55 -0500 (CDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2338 Lines: 71 --SidV/bKy1CyabPX8 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable w1_io.c 1.7 w1_reset_bus, added some comments about the timing and switched to msleep for the later delay. I don't have the hardware to test the sleep after reset change. The one wire doesn't have a timing = requirement between commands so it is fine. I do have the USB = hardware and it would be in big trouble with 10ms interrupt trans= fers to find that the reset completed. Signed-off-by: David Fries --- drivers/w1/w1_io.c | 14 +++++++++++++- 1 files changed, 13 insertions(+), 1 deletions(-) diff --git a/drivers/w1/w1_io.c b/drivers/w1/w1_io.c index 46c6994..9238758 100644 --- a/drivers/w1/w1_io.c +++ b/drivers/w1/w1_io.c @@ -291,12 +291,24 @@ int w1_reset_bus(struct w1_master *dev) result =3D dev->bus_master->reset_bus(dev->bus_master->data) & 0x1; else { dev->bus_master->write_bit(dev->bus_master->data, 0); + /* minimum 480, max ? us + * be nice and sleep, except 18b20 spec lists 960us maximum, + * so until we can sleep with microsecond accuracy, spin. + * Feel free to come up with some other way to give up the + * cpu for such a short amount of time AND get it back in + * the maximum amount of time. + */ w1_delay(480); dev->bus_master->write_bit(dev->bus_master->data, 1); w1_delay(70); =20 result =3D dev->bus_master->read_bit(dev->bus_master->data) & 0x1; - w1_delay(410); + /* minmum 70 (above) + 410 =3D 480 us + * There aren't any timing requirements between a reset and + * the following transactions. Sleeping is safe here. + */ + /* w1_delay(410); min required time */ + msleep(1); } =20 return result; --=20 1.4.4.4 --SidV/bKy1CyabPX8 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (GNU/Linux) iD8DBQFH7OQPAI852cse6PARAtCPAKCP5epzW8m6J6oRLPQkYpdr3IVRWQCgvGul xpj2Qs1/PejcVj4xkaAEICI= =srWe -----END PGP SIGNATURE----- --SidV/bKy1CyabPX8-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/