Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754832Ab3EVBnp (ORCPT ); Tue, 21 May 2013 21:43:45 -0400 Received: from avon.wwwdotorg.org ([70.85.31.133]:42557 "EHLO avon.wwwdotorg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753519Ab3EVBnn (ORCPT ); Tue, 21 May 2013 21:43:43 -0400 Message-ID: <519C22CB.5040009@wwwdotorg.org> Date: Tue, 21 May 2013 19:43:39 -0600 From: Stephen Warren User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130308 Thunderbird/17.0.4 MIME-Version: 1.0 To: Jongsung Kim CC: linux@arm.linux.org.uk, gregkh@linuxfoundation.org, jslaby@suse.cz, linux-serial@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ARM: bcm2835: override the HW UART periphid References: <519AD82A.6090809@wwwdotorg.org> <1369116149-2361-1-git-send-email-neidhard.kim@lge.com> <519BA209.6050407@wwwdotorg.org> In-Reply-To: <519BA209.6050407@wwwdotorg.org> X-Enigmail-Version: 1.4.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1553 Lines: 34 On 05/21/2013 10:34 AM, Stephen Warren wrote: > On 05/21/2013 12:02 AM, Jongsung Kim wrote: >> Stephen Warren reported the recent commit 78506f2 (add support for >> extended FIFO-size of PL011-r1p5) breaks the serial port on the >> BCM2835 ARM SoC. >> >> A UART compatible with the ARM PL011-r1p5 should have 32-deep FIFOs. >> The BCM2835 UART just looks like an ARM PL011-r1p5, but has 16-deep >> FIFOs just like PL011-r1p4 or earlier revisions. As a workaround for >> this compatibility issue, this patch overrides the HW UART periphid >> register values with the actually compatible UART periphid 0x00241011 >> (r1p3 or r1p4). >> >> Reported-by: Stephen Warren >> Signed-off-by: Jongsung Kim > > I know this will work, because I tried out the same thing last week. > > However, I'm not convinced that it's the correct approach. What other > changes exist between r1p4 and r1p5; can you check in the TRM? Looking at the TRM, it seems this is really the only change, according to the changelog in the documentation (although it's a little difficult to tell since the document seems to have a bunch of changes that presumably don't affect behaviour). So, faking the periphid seems OK. Acked-by: Stephen Warren Let's apply for 3.10. -- 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/