From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by aws-us-west-2-korg-lkml-1.web.codeaurora.org (Postfix) with ESMTP id E6756C5CFF1 for ; Tue, 12 Jun 2018 13:04:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A33CD208B2 for ; Tue, 12 Jun 2018 13:04:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A33CD208B2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933612AbeFLNEp (ORCPT ); Tue, 12 Jun 2018 09:04:45 -0400 Received: from mga03.intel.com ([134.134.136.65]:59949 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932565AbeFLNEo (ORCPT ); Tue, 12 Jun 2018 09:04:44 -0400 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 12 Jun 2018 06:04:43 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,214,1526367600"; d="scan'208";a="62477248" Received: from shbuild888.sh.intel.com (HELO localhost) ([10.239.146.239]) by fmsmga004.fm.intel.com with ESMTP; 12 Jun 2018 06:04:41 -0700 Date: Tue, 12 Jun 2018 21:06:40 +0800 From: Feng Tang To: Shawn Lin Cc: Ulf Hansson , Linux Kernel Mailing List , "linux-mmc@vger.kernel.org" , Greg Kroah-Hartman , Adrian Hunter Subject: Re: [PATCH] mmc: Move the mmc driver init earlier Message-ID: <20180612130640.yzuifhrlfs3lefuc@shbuild888> References: <20180608095154.22413-1-feng.tang@intel.com> <20180612084234.gjzq66xsqblryrkm@shbuild888> <03aa85b4-74cf-621c-08cf-271b4c0d8e8c@rock-chips.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <03aa85b4-74cf-621c-08cf-271b4c0d8e8c@rock-chips.com> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 12, 2018 at 08:05:25PM +0800, Shawn Lin wrote: > On 2018/6/12 18:29, Ulf Hansson wrote: > > On 12 June 2018 at 10:42, Feng Tang wrote: > > > Hi Ulf, > > > > > > Thanks for the review. > > > > > > On Tue, Jun 12, 2018 at 08:25:44AM +0200, Ulf Hansson wrote: > > > > On 8 June 2018 at 11:51, Feng Tang wrote: > > > > > When doing some boot time optimization for an eMMC rootfs NUCs, > > > > > we found the rootfs may spend around 100 microseconds waiting > > > > > for eMMC card to be initialized, then the rootfs could be > > > > > mounted. > > > > > [ 1.216561] Waiting for root device /dev/mmcblk1p1... > > > > > [ 1.289262] mmc1: new HS400 MMC card at address 0001 > > > > > [ 1.289667] mmcblk1: mmc1:0001 R1J56L 14.7 GiB > > > > > [ 1.289772] mmcblk1boot0: mmc1:0001 R1J56L partition 1 8.00 MiB > > > > > [ 1.289869] mmcblk1boot1: mmc1:0001 R1J56L partition 2 8.00 MiB > > > > > [ 1.289967] mmcblk1rpmb: mmc1:0001 R1J56L partition 3 4.00 MiB > > > > > [ 1.292798] mmcblk1: p1 p2 p3 > > > > > [ 1.300576] EXT4-fs (mmcblk1p1): couldn't mount as ext3 due to feature incompatibilities > > > > > [ 1.300912] EXT4-fs (mmcblk1p1): couldn't mount as ext2 due to feature incompatibilities > > > > > > > > > > And this is a common problem for smartphones, tablets, embedded > > > > > devices and automotive products. This patch will make the eMMC/SD > > > > > card start initializing earlier, by changing its order in drivers/Makefile. > > > > > > > > > > On our platform, the waiting for eMMC card is almost eliminated with the patch, > > > > > which is critical to boot time. > > > > > > > > I am wondering what kernel version you are running here. There have > > > > been some changes to the mmc initialization path, which perhaps can > > > > help. > > > These logs in commit msg are based on kernel 4.14, and the patch is generated > > > against kernel 4.17. > > > > Right. So it's quite recent, even if lot's of changes have been made > > to the mmc core since then. > > > > A few things (old/new) that is important. > > 1) Check if your mmc host driver support MMC_CAP_WAIT_WHILE_BUSY. That > > should have some effect, avoiding unnecessary polling. > > > > 2) Since 4.18 rc1, you will be able to configure an over estimated > > "power on" delay (via DT as well). Look at commit > > 6d796c68cd15234a33a4bd2ef7231125fea2dc6c. > > Sorry to chime in. We could also reduce the "power on" delay via hosts' > ->set_ios() callback. > > > > > 3) If you use a DT based platform, I think what people do is to > > re-organize the order of device nodes, such that as many as possible > > -EPROBE_DEFER is avoided to be returned by drivers. This is also not a > > good solution, but the best we have at this moment. > > Also DT based platform is allowed to add no-sd and no-sdio for the eMMC > node, which could slighly help reduce the boot time. > You could refer to Documentation/devicetree/bindings/mmc/mmc.txt for > details. Thanks Shawn for your tips, we did simliar thing :) for no-sd and no-sdio, and even disabled SDHCI controller that has nothing connected. - Feng