From owner-freebsd-stable@FreeBSD.ORG Wed Sep 30 11:19:49 2009 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id CD87A106568B for ; Wed, 30 Sep 2009 11:19:49 +0000 (UTC) (envelope-from doconnor@gsoft.com.au) Received: from cain.gsoft.com.au (cain.gsoft.com.au [203.31.81.10]) by mx1.freebsd.org (Postfix) with ESMTP id 455B78FC12 for ; Wed, 30 Sep 2009 11:19:48 +0000 (UTC) Received: from inchoate.gsoft.com.au (ppp121-45-212-218.lns11.adl2.internode.on.net [121.45.212.218]) (authenticated bits=0) by cain.gsoft.com.au (8.13.8/8.13.8) with ESMTP id n8UBJkMn051232 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO); Wed, 30 Sep 2009 20:49:47 +0930 (CST) (envelope-from doconnor@gsoft.com.au) From: "Daniel O'Connor" To: freebsd-stable@freebsd.org Date: Wed, 30 Sep 2009 20:49:22 +0930 User-Agent: KMail/1.9.10 MIME-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart2229981.rP8oQUmKAR"; protocol="application/pgp-signature"; micalg=pgp-sha1 Content-Transfer-Encoding: 7bit Message-Id: <200909302049.43344.doconnor@gsoft.com.au> X-Spam-Score: -2.212 () BAYES_00,RDNS_DYNAMIC X-Scanned-By: MIMEDefang 2.63 on 203.31.81.10 Subject: PCI write oddity X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 30 Sep 2009 11:19:49 -0000 --nextPart2229981.rP8oQUmKAR Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Hi, I have a custom device driver for a PCI RS485 card - it has a 16550 and=20 a PLX PCI bridge on it and I recently found something quite odd. We used to run the link at 9600 but with some more recent modules we've=20 decided to up it to 115200, so I changed the baud rate easily enough..=20 However while the bit rate is correct each byte going out has a 1=20 millisecond delay(!). What is really odd is that when I added some=20 debugging to log how long each write to the FIFO register took I=20 discovered it was 1 millisecond. Reads from the same register take ~5 usec which seems more like it. Does anyone have any idea why it would be so damn slow? =2D-=20 Daniel O'Connor software and network engineer for Genesis Software - http://www.gsoft.com.au "The nice thing about standards is that there are so many of them to choose from." -- Andrew Tanenbaum GPG Fingerprint - 5596 B766 97C0 0E94 4347 295E E593 DC20 7B3F CE8C --nextPart2229981.rP8oQUmKAR Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.12 (FreeBSD) iD8DBQBKwz7P5ZPcIHs/zowRAsC7AJsFOOxJ6EROLCyckvq9KpgK/KATnACgpiEM La7/qKxiHNZJWZz0CG6Vby0= =Qvtl -----END PGP SIGNATURE----- --nextPart2229981.rP8oQUmKAR--