Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261203AbVCKQrP (ORCPT ); Fri, 11 Mar 2005 11:47:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261206AbVCKQrP (ORCPT ); Fri, 11 Mar 2005 11:47:15 -0500 Received: from pentafluge.infradead.org ([213.146.154.40]:32980 "EHLO pentafluge.infradead.org") by vger.kernel.org with ESMTP id S261203AbVCKQrC (ORCPT ); Fri, 11 Mar 2005 11:47:02 -0500 Subject: Re: [ patch 3/5] drivers/serial/jsm: new serial device driver From: Arjan van de Ven To: Wen Xiong Cc: Greg KH , linux-kernel@vger.kernel.org In-Reply-To: <4231C9B2.5020202@us.ltcfwd.linux.ibm.com> References: <20050228063954.GB23595@kroah.com> <4228CE41.2000102@us.ltcfwd.linux.ibm.com> <20050304220116.GA1201@kroah.com> <422CD9DB.10103@us.ltcfwd.linux.ibm.com> <20050308064424.GF17022@kroah.com> <422DF525.8030606@us.ltcfwd.linux.ibm.com> <20050308235807.GA11807@kroah.com> <422F1A8A.4000106@us.ltcfwd.linux.ibm.com> <20050309163518.GC25079@kroah.com> <422F2FDD.4050908@us.ltcfwd.linux.ibm.com> <20050309185800.GA27268@kroah.com> <4231BB5D.8020400@us.ltcfwd.linux.ibm.com> <1110556428.9917.31.camel@laptopd505.fenrus.org> <4231C9B2.5020202@us.ltcfwd.linux.ibm.com> Content-Type: text/plain Date: Fri, 11 Mar 2005 17:46:54 +0100 Message-Id: <1110559614.9917.43.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.0.2 (2.0.2-3) Content-Transfer-Encoding: 7bit X-Spam-Score: 4.1 (++++) X-Spam-Report: SpamAssassin version 2.63 on pentafluge.infradead.org summary: Content analysis details: (4.1 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- 0.3 RCVD_NUMERIC_HELO Received: contains a numeric HELO 1.1 RCVD_IN_DSBL RBL: Received via a relay in list.dsbl.org [] 2.5 RCVD_IN_DYNABLOCK RBL: Sent directly from dynamic IP address [80.57.133.107 listed in dnsbl.sorbs.net] 0.1 RCVD_IN_SORBS RBL: SORBS: sender is listed in SORBS [80.57.133.107 listed in dnsbl.sorbs.net] X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1207 Lines: 27 > Jeff pointed out several PCI posting errors last time. Before we used > udelay and now we changed to readb/readl instead of udelay this time. > But we only used PCI posting when we think maybe delay there. > So we have to do PCI posting on every writeb? not every > Do you have some rules for > doing PCI posting while writeb? depends on what kind of registers? basically you need to do posting flushes after every write for which you assume later on the hardware received the write. If you do 5 writes in a row you don't need 5 flushes. If you do a read later always anyway you don't need any flushes. On the other side of the spectrum: if you do something to the hardware and then wait for some event, you do need to flush that stuff. So at minimum you want to make sure that at any point where you leave the driver (to userspace or tty layer or ...) all writes have been flushed. And at all points where you are going to wait for hardware events. - 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/