Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752498Ab3C0M2e (ORCPT ); Wed, 27 Mar 2013 08:28:34 -0400 Received: from mail-ve0-f177.google.com ([209.85.128.177]:48815 "EHLO mail-ve0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752315Ab3C0M2c (ORCPT ); Wed, 27 Mar 2013 08:28:32 -0400 MIME-Version: 1.0 In-Reply-To: References: <1363223183-3772-1-git-send-email-ynvich@gmail.com> <1363224194-7366-1-git-send-email-ynvich@gmail.com> <87620jmkoe.fsf@octavius.laptop.org> Date: Wed, 27 Mar 2013 16:28:31 +0400 Message-ID: Subject: Re: [PATCH v2] wait while adding MMC host to ensure root mounts From: =?UTF-8?B?0KHQtdGA0LPQtdC5INCv0L3QvtCy0LjRhw==?= To: Ulf Hansson Cc: Chris Ball , Greg Kroah-Hartman , Linus Walleij , Jaehoon Chung , Namjae Jeon , linux-kernel@vger.kernel.org, linux-mmc@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1259 Lines: 26 Hi Ulf, On 27 March 2013 15:13, Ulf Hansson wrote: > Moreover, this patch will have bad impact on booting the kernel, since > every host device that has scheduled a detect work from it's probe > function will also wait for it to finish. Even if it is the boot > device of not. If this is needed, I would prefer that a host cap is > used. Do you have any profiling data supporting bad impact on boot? It should be it in the range of dozens us, if any. Without the patch, approx. 30% of boots succeeded with CONFIG_PREEMT and aprox. 95% without CONFIG_PREEMT. mmc_rescan is just a few instructions, if there is no card present. On boot and with a card present, it might only sleep in the host implementation. Anyway, something had to be done about mmc boot. rootdelay will not report error if the card is absent or its partition table is damaged. rootdelay is a workaround by definition, so it may occasionally fail if it is too small. Big rootdealy has a clear bad impact on boot time. -- 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/