Message-ID: <5141BB44.2020902@gmail.com>
Date: Thu, 14 Mar 2013 15:57:56 +0400
From: Sergey Yanovich <ynvich@gmail.com>
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To: Namjae Jeon <linkinjeon@gmail.com>
CC: Chris Ball <cjb@laptop.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        Jaehoon Chung <jh80.chung@samsung.com>, linux-kernel@vger.kernel.org,
        linux-mmc@vger.kernel.org
Subject: Re: [PATCH v2] wait while adding MMC host to ensure root mounts
References: <1363223183-3772-1-git-send-email-ynvich@gmail.com> <1363224194-7366-1-git-send-email-ynvich@gmail.com> <CAKYAXd_v5TsMJ+h3Zk4FRDB0jAfF04t4Z65D1kmB1ziOk65+Vg@mail.gmail.com>
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On 14/03/13 08:08, Namjae Jeon wrote:> 2013/3/14, Sergey Yanovich <ynvich@gmail.com>:
>> Kernel panic - not syncing: VFS: Unable to mount root fs on
>> unknown-block(0,0)

> Have you ever tried to use rootwait or rootdelay on command line ?
> If no, You can use them.

Those options work. However, they introduce a delay in the range of hundreds milliseconds and seconds respectively. They delay is not required. If a cards is present, mmc_rescan will return synchronously with card initialized.

prepare_namespace() uses wait_for_device_probe(). The latter assumes that all "known devices" have initialized by the time it returns. MMC is not currently delivering on the assumptions. It will with the patch applied.
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