Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758011AbYC1MyJ (ORCPT ); Fri, 28 Mar 2008 08:54:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756922AbYC1Mv4 (ORCPT ); Fri, 28 Mar 2008 08:51:56 -0400 Received: from SpacedOut.fries.net ([67.64.210.234]:56326 "EHLO SpacedOut.fries.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756906AbYC1Mvz (ORCPT ); Fri, 28 Mar 2008 08:51:55 -0400 Date: Fri, 28 Mar 2008 07:27:29 -0500 From: David Fries To: linux-kernel@vger.kernel.org Cc: Evgeniy Polyakov Subject: [PATCH 28/35] W1: ds2490.c simplify and fix ds_touch_bit Message-ID: <20080328122729.GC3613@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="A1Iwnsx6rNfRhs6P" 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 07:27:30 -0500 (CDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2803 Lines: 88 --A1Iwnsx6rNfRhs6P Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable ds2490.c 1.15 Simplify and fix ds_touch_bit. If a device is attached in the middle of a bus search the status register will return more than the default 16 bytes. The additional bytes indicate that it has detected a new device. The way ds_wait_status is coded, if it doesn't read 16 status bytes it returns an error value. ds_touch_bit then will detect that error and return an error. In that case it doesn't read the input buffer and returns uninitialized data. It doesn't stop there. The next transaction will not expect the extra byte in the input buffer and the short read will cause an error and clear out both the old byte and new data in the input buffer. Just ignore the value of ds_wait_status. It is still required to wait until ds2490 is again idle and there is data to read when ds_recv_data is called. This also removes the while loop. None of the other commands wait and verify that the issued command is in the status register. Signed-off-by: David Fries --- drivers/w1/masters/ds2490.c | 21 ++++----------------- 1 files changed, 4 insertions(+), 17 deletions(-) diff --git a/drivers/w1/masters/ds2490.c b/drivers/w1/masters/ds2490.c index 8c3d756..45e7f10 100644 --- a/drivers/w1/masters/ds2490.c +++ b/drivers/w1/masters/ds2490.c @@ -490,28 +490,15 @@ static int ds_set_pullup(struct ds_device *dev, int d= elay) =20 static int ds_touch_bit(struct ds_device *dev, u8 bit, u8 *tbit) { - int err, count; + int err; struct ds_status st; - u16 value =3D (COMM_BIT_IO | COMM_IM) | ((bit) ? COMM_D : 0); - u16 cmd; =20 - err =3D ds_send_control(dev, value, 0); + err =3D ds_send_control(dev, COMM_BIT_IO | COMM_IM | (bit ? COMM_D : 0), + 0); if (err) return err; =20 - count =3D 0; - do { - err =3D ds_wait_status(dev, &st); - if (err) - return err; - - cmd =3D st.command0 | (st.command1 << 8); - } while (cmd !=3D value && ++count < 10); - - if (err < 0 || count >=3D 10) { - printk(KERN_ERR "Failed to obtain status.\n"); - return -EINVAL; - } + ds_wait_status(dev, &st); =20 err =3D ds_recv_data(dev, tbit, sizeof(*tbit)); if (err < 0) --=20 1.4.4.4 --A1Iwnsx6rNfRhs6P Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (GNU/Linux) iD8DBQFH7OQxAI852cse6PARAqYfAKCQe9d2nU4+12OOhM3pHgS3ZSd2ngCgug7/ Van07jWiZ3gOZOjw9KFHuPQ= =pd/l -----END PGP SIGNATURE----- --A1Iwnsx6rNfRhs6P-- -- 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/