From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Egger Subject: Re: [PATCH] xen: more robust serial port driver Date: Tue, 28 Jul 2009 16:47:36 +0200 Message-ID: <200907281647.36341.Christoph.Egger@amd.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: xen-devel@lists.xensource.com Cc: Keir Fraser List-Id: xen-devel@lists.xenproject.org On Tuesday 28 July 2009 16:15:42 Keir Fraser wrote: > On 28/07/2009 15:07, "Christoph Egger" wrote: > > Attached patch adds a check if the fifo is usable before we > > actually use it. > > I count that at least the first two chunks and the initialisation of > tx_fifo_size are unnecessary. First hunk: It looks suspicious returning a value of type void. Second hunk and initialization of tx_fifo_size: If you are sure these initializations are duplicates, then they are unnecessary. > Might this be the case for the udelay(100) as > well? No. This ensures, that the write takes effect before the read happens. > And what kinds of systems have these broken UARTs that half-advertise > a broken/non-existent FIFO? The original ns16550 has a broken FIFO. The ns16450 has no FIFO. There are simulators which simulate those old things instead of a ns16550a. Christoph -- ---to satisfy European Law for business letters: Advanced Micro Devices GmbH Karl-Hammerschmidt-Str. 34, 85609 Dornach b. Muenchen Geschaeftsfuehrer: Thomas M. McCoy, Giuliano Meroni Sitz: Dornach, Gemeinde Aschheim, Landkreis Muenchen Registergericht Muenchen, HRB Nr. 43632