Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757469AbYG2CYd (ORCPT ); Mon, 28 Jul 2008 22:24:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756476AbYG2CYR (ORCPT ); Mon, 28 Jul 2008 22:24:17 -0400 Received: from SpacedOut.fries.net ([67.64.210.234]:50125 "EHLO SpacedOut.fries.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756275AbYG2CYQ (ORCPT ); Mon, 28 Jul 2008 22:24:16 -0400 Date: Mon, 28 Jul 2008 21:24:11 -0500 From: David Fries To: Andrew Morton Cc: linux-kernel@vger.kernel.org, Evgeniy Polyakov Subject: [PATCH 17/30] W1: w1_io.c reset comments and msleep Message-ID: <20080729022411.GQ24452@spacedout.fries.net> References: <20080729020433.GA24424@spacedout.fries.net> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="5KxTQ9fdN6Op3ksq" Content-Disposition: inline In-Reply-To: <20080729020433.GA24424@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]); Mon, 28 Jul 2008 21:24:12 -0500 (CDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2380 Lines: 71 --5KxTQ9fdN6Op3ksq Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable 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 Signed-off-by: Evgeniy Polyakov --- 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 a2f0d5f..dd2ecef 100644 --- a/drivers/w1/w1_io.c +++ b/drivers/w1/w1_io.c @@ -293,12 +293,24 @@ 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 --5KxTQ9fdN6Op3ksq Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (GNU/Linux) iD8DBQFIjn9LAI852cse6PARAlugAKCoFqhPNx99Xc0i3badehtbIyLQIACeMDfI nrg8UhwjU4qLFG481Gb7Cc0= =q9j1 -----END PGP SIGNATURE----- --5KxTQ9fdN6Op3ksq-- -- 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/