From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757898AbcDACCE (ORCPT ); Thu, 31 Mar 2016 22:02:04 -0400 Received: from avon.wwwdotorg.org ([70.85.31.133]:42256 "EHLO avon.wwwdotorg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753684AbcDACCC (ORCPT ); Thu, 31 Mar 2016 22:02:02 -0400 Subject: Re: [PATCH 2/3] ARM: multi_v7_defconfig: Switch BCM2835 to sdhci-iproc.c for MMC To: Eric Anholt References: <1459470504-5007-1-git-send-email-eric@anholt.net> <1459470504-5007-2-git-send-email-eric@anholt.net> Cc: linux-rpi-kernel@lists.infradead.org, Russell King , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Lee Jones , Florian Fainelli From: Stephen Warren Message-ID: <56FDD697.2050901@wwwdotorg.org> Date: Thu, 31 Mar 2016 20:01:59 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <1459470504-5007-2-git-send-email-eric@anholt.net> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/31/2016 06:28 PM, Eric Anholt wrote: > This approximately triples write performance for the SD card. My card > is too full of important data to collect very reliable numbers, but I > see 271.361% +/- 166.742% improvement (n=3 before, 6 after), for 'dd > if=/dev/zero of=/boot/asdf bs=1M count=3 oflag=dsync,direct'. Read > performance appears to be unaffected. I thought that switching the defconfig wasn't possible, since this HW module relies on the SoC core clock, and that can be asynchronously changed by the FW running on the VideoCore. Consequently, this change isn't safe unless the user puts non-default options in their config.txt. The same comment applies to "[PATCH 1/4] ARM: bcm2835: Switch BCM2835 to sdhci-iproc.c for MMC" in the other series.