From: Knut Wohlrab <knut.wohlrab@de.bosch.com>
To: Jassi Brar <jaswinder.singh@linaro.org>
Cc: "linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
"Behme Dirk (CM-AI/PJ-CF32)" <Dirk.Behme@de.bosch.com>
Subject: Re: Devicetree: Initialization order of mmc block devices?
Date: Wed, 18 Jul 2012 16:11:25 +0200 [thread overview]
Message-ID: <5006C40D.300@de.bosch.com> (raw)
In-Reply-To: <CAJe_Zhfmn4dUHk6xtudwCEurigvX64xce3VAozdjDdpSWSbRkA@mail.gmail.com>
On 07/18/2012 03:47 PM, Jassi Brar wrote:
> On 18 July 2012 15:19, Knut Wohlrab <knut.wohlrab@de.bosch.com> wrote:
>
>> If a SD card is inserted at boot time, its "mmcblk0", the embedded
>> MMC (eMMC) device "mmcblk1". This makes it difficult to give the kernel the
>> correct device for the eMMC root file system ("root=/dev/mmcblk?p1 ...").
>>
> How about root=UUID=<eMMC-partition> ?
Because we are talking about an embedded device, it is very difficult to
get a UUID of a eMMC partition into kernel command line with U-Boot.
Handling of UUID is also a big effort at board manufacturing.
Startup speed is very important for us. Searching for UUID on several
MMC/SD devices will significant slow down the boot process.
This problem can occur on many devices with embedded MMC and removable
SD, e.g. smart phones. So I think we should find an solution to define
MMC scan order or device number/name in a device tree.
Thanks and regards
Knut
WARNING: multiple messages have this Message-ID (diff)
From: knut.wohlrab@de.bosch.com (Knut Wohlrab)
To: linux-arm-kernel@lists.infradead.org
Subject: Devicetree: Initialization order of mmc block devices?
Date: Wed, 18 Jul 2012 16:11:25 +0200 [thread overview]
Message-ID: <5006C40D.300@de.bosch.com> (raw)
In-Reply-To: <CAJe_Zhfmn4dUHk6xtudwCEurigvX64xce3VAozdjDdpSWSbRkA@mail.gmail.com>
On 07/18/2012 03:47 PM, Jassi Brar wrote:
> On 18 July 2012 15:19, Knut Wohlrab <knut.wohlrab@de.bosch.com> wrote:
>
>> If a SD card is inserted at boot time, its "mmcblk0", the embedded
>> MMC (eMMC) device "mmcblk1". This makes it difficult to give the kernel the
>> correct device for the eMMC root file system ("root=/dev/mmcblk?p1 ...").
>>
> How about root=UUID=<eMMC-partition> ?
Because we are talking about an embedded device, it is very difficult to
get a UUID of a eMMC partition into kernel command line with U-Boot.
Handling of UUID is also a big effort at board manufacturing.
Startup speed is very important for us. Searching for UUID on several
MMC/SD devices will significant slow down the boot process.
This problem can occur on many devices with embedded MMC and removable
SD, e.g. smart phones. So I think we should find an solution to define
MMC scan order or device number/name in a device tree.
Thanks and regards
Knut
next prev parent reply other threads:[~2012-07-18 14:14 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-18 6:26 Devicetree: Initialization order of mmc block devices? Dirk Behme
2012-07-18 6:26 ` Dirk Behme
2012-07-18 7:23 ` Jassi Brar
2012-07-18 7:23 ` Jassi Brar
2012-07-18 9:49 ` Knut Wohlrab
2012-07-18 9:49 ` Knut Wohlrab
2012-07-18 13:47 ` Jassi Brar
2012-07-18 13:47 ` Jassi Brar
2012-07-18 14:11 ` Knut Wohlrab [this message]
2012-07-18 14:11 ` Knut Wohlrab
2012-07-18 14:54 ` Eric Nelson
2012-07-18 14:54 ` Eric Nelson
2012-07-18 15:16 ` Knut Wohlrab
2012-07-18 15:16 ` Knut Wohlrab
2012-07-19 8:07 ` Thomas Petazzoni
2012-07-19 8:07 ` Thomas Petazzoni
2012-07-19 14:08 ` Matthias Kaehlcke
2012-07-19 14:08 ` Matthias Kaehlcke
2012-07-19 20:45 ` Jassi Brar
2012-07-19 20:45 ` Jassi Brar
2012-07-20 11:30 ` Dirk Behme
2012-07-20 11:30 ` Dirk Behme
2012-07-20 11:56 ` Jassi Brar
2012-07-20 11:56 ` Jassi Brar
2012-07-26 9:16 ` Dirk Behme
2012-07-26 9:16 ` Dirk Behme
2012-07-26 9:39 ` Jassi Brar
2012-07-26 9:39 ` Jassi Brar
2012-07-19 13:13 ` Arnd Bergmann
2012-07-19 13:13 ` Arnd Bergmann
2012-07-26 8:06 ` Dirk Behme
2012-07-26 8:06 ` Dirk Behme
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