From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751731AbaHRQij (ORCPT ); Mon, 18 Aug 2014 12:38:39 -0400 Received: from devils.ext.ti.com ([198.47.26.153]:51060 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751091AbaHRQih (ORCPT ); Mon, 18 Aug 2014 12:38:37 -0400 Date: Mon, 18 Aug 2014 11:37:57 -0500 From: Felipe Balbi To: Peter Hurley CC: Tony Lindgren , Sebastian Andrzej Siewior , Lennart Sorensen , , , , , , Vinod Koul , Greg Kroah-Hartman Subject: Re: [PATCH v7] 8250-core based serial driver for OMAP + DMA Message-ID: <20140818163757.GK9662@saruman.home> Reply-To: References: <1408124563-31541-1-git-send-email-bigeasy@linutronix.de> <20140815181704.GH17769@csclub.uwaterloo.ca> <53EE5BF8.3010007@linutronix.de> <20140815202826.GC9239@atomide.com> <53F21885.605@hurleysoftware.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="zYjDATHXTWnytHRU" Content-Disposition: inline In-Reply-To: <53F21885.605@hurleysoftware.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --zYjDATHXTWnytHRU Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Aug 18, 2014 at 11:15:17AM -0400, Peter Hurley wrote: > On 08/15/2014 04:28 PM, Tony Lindgren wrote: > > * Sebastian Andrzej Siewior [140815 12:16]: > >> On 08/15/2014 08:17 PM, Lennart Sorensen wrote: > >> > >>> Are you saying that with the new driver you have to respond to the RX > >>> irq faster than before to avoid overflows? It is not quite clear. > >> > >> Yes. The irq fires 46 bytes giving you 16 bytes buffer before overflow > >> vs 63 bytes buffer the old one had. > >> > >>> I do think 40000 interrupts to handle 40000 bytes of date does seem a > >>> tad inefficient, so dropping to 854 looks a lot nicer. Was the omap > >>> driver not using the fifo trigger levels at all? > >> > >> It configured the trigger levels to 1 for RX and 16 for TX. > >=20 > > Hmm that weird RX trigger level is a workaround for lost characters. > >=20 > > See commit 0ba5f66836 (tty: serial: OMAP: use a 1-byte RX FIFO > > threshold in PIO mode :) >=20 > That commit looks like it should have been specific to the silicon > exhibiting the rx timeout bug. yeah, I'll agree with that. --=20 balbi --zYjDATHXTWnytHRU Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJT8ivlAAoJEIaOsuA1yqRE9lAQAJCVcSUkGXurWEFy590wHY0v r+8k7+Qd0aMWTXHzENSaZCi6IGvjN2NWj2FOoCazinPOoDbMVzl4rNIdNzzqiJTm BbsReb4J1xR0KIN1vgkpwxwcqlre+GQY88i7o8BBaNJey0Rm68iSgCjgH1WQzbmG I1CIDZbZMCKAYhOKZGvNVUVqif30KSCvDtr7DEubzIaq0ktU4DRhQOvZr2LX2VYC aN4VEEmqTBeJ/mbkEnVKWVdoWi5hXsMYZAT9NCMuDm/xhARLBTsY4RyAu49UrIja NaNTbbED8h0HfNxCto2IDTtIiNoDExm2BK1bIJ4tAs8Rl5UWbcozHJnrW4lEDdl1 6koGFUJL408mEzXrHuTNvE/yrKqRprP2L/o78lMN4eZlGdg4B4pdcozrqkDaLl5g SHr/3FKcIK9Wem+O59JVsp6+K2p0o7nEdWfEeOjhLGWpCLGWgy/cQ7+R6eMbuWYM SNSPW2GH2SRsN19tI9i1DGlf9tOayiMxKhV0WvEljOoIEdx+9vtO5fG0yJS2aPxs BpUEZWqJKoB5iUSKh2Vi39MHZqiK/KMNKZNH7/p94IpKEmXCkpA0zVI3WtbK+773 F1E65SvW/Tl9na2mgzkL7rZdvL3PbYQvND8nE4rpr9oR/52TrmASLbAge180HObo c3lloT7Xiv/y5nTlFZEI =3I5x -----END PGP SIGNATURE----- --zYjDATHXTWnytHRU--