From owner-svn-src-all@freebsd.org Wed Mar 8 19:35:27 2017 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 21248D02281; Wed, 8 Mar 2017 19:35:27 +0000 (UTC) (envelope-from freebsd@pdx.rh.CN85.dnsmgr.net) Received: from pdx.rh.CN85.dnsmgr.net (br1.CN84in.dnsmgr.net [69.59.192.140]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id BB6BD1107; Wed, 8 Mar 2017 19:35:26 +0000 (UTC) (envelope-from freebsd@pdx.rh.CN85.dnsmgr.net) Received: from pdx.rh.CN85.dnsmgr.net (localhost [127.0.0.1]) by pdx.rh.CN85.dnsmgr.net (8.13.3/8.13.3) with ESMTP id v28JZMFM002381; Wed, 8 Mar 2017 11:35:22 -0800 (PST) (envelope-from freebsd@pdx.rh.CN85.dnsmgr.net) Received: (from freebsd@localhost) by pdx.rh.CN85.dnsmgr.net (8.13.3/8.13.3/Submit) id v28JZLTv002380; Wed, 8 Mar 2017 11:35:21 -0800 (PST) (envelope-from freebsd) From: "Rodney W. Grimes" Message-Id: <201703081935.v28JZLTv002380@pdx.rh.CN85.dnsmgr.net> Subject: Re: svn commit: r314917 - head/sys/dev/uart In-Reply-To: <201703081853.v28IrWhm099535@repo.freebsd.org> To: Ian Lepore Date: Wed, 8 Mar 2017 11:35:21 -0800 (PST) CC: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Reply-To: rgrimes@freebsd.org X-Mailer: ELM [version 2.4ME+ PL121h (25)] MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 08 Mar 2017 19:35:27 -0000 [ Charset UTF-8 unsupported, converting... ] > Author: ian > Date: Wed Mar 8 18:53:32 2017 > New Revision: 314917 > URL: https://svnweb.freebsd.org/changeset/base/314917 > > Log: > Handle fifo size differences between older and newer revs of pl011 hardware. > > Starting with rev 5 (which is inexplicably indicated by a version number > of '3' in the Peripheral ID register), the pl011 doubled the size of the > rx and tx fifos, to 32 bytes, so read the ID register and set the size > variables in the softc accordingly. > > An interesting wrinkle in this otherwise-simple concept is that the > bcm2835 SoC, used in Raspberry Pi systems among others, has the rev 5 > pl011 hardware, but somehow also has the older 16-byte fifos. We check > the FDT data to see if the hardware is part of a bcm283x system and use > the smaller size if so. The chip compiler probably has a parameter to set fifo depth, this would normally be independent of the IP revision. -- Rod Grimes rgrimes@freebsd.org