From: Jaehoon Chung <jh80.chung@samsung.com>
To: u-boot@lists.denx.de
Subject: [U-Boot] Are mmc open/close subcommands needed?
Date: Thu, 09 Jan 2014 17:45:55 +0900 [thread overview]
Message-ID: <52CE61C3.3090204@samsung.com> (raw)
In-Reply-To: <52CBB107.9050607@digi.com>
On 01/07/2014 04:47 PM, Hector Palacios wrote:
> Dear Otavio,
>
> On 01/03/2014 06:35 PM, Otavio Salvador wrote:
>> On Thu, Jan 2, 2014 at 9:36 PM, Marek Vasut <marex@denx.de> wrote:
>>> On Thursday, January 02, 2014 at 05:53:00 PM, Hector Palacios wrote:
>>>> Hi,
>>>>
>>>> I saw commit 2a91c9134675140853577b565210458b5774e6cf that introduces mmc
>>>> subcommands 'open' and 'close' to access eMMC boot partitions and was
>>>> wondering if they are really needed. Can't the same be achieved with
>>>> already existing 'mmc dev [dev] [part]' command?
>>>>
>>>> mmc open <dev> <boot_partition>
>>>> is the same as
>>>> mmc dev <dev> <part>
>>>> where <part> is the boot partition
>>>>
>>>> mmc close <dev> <boot_partition>
>>>> is the same as
>>>> mmc dev <dev> 0
>>>> as a 0 will switch to partition 0 (user data).
>>>>
>>>> Best regards,
>>>> --
>>>> Hector Palacios
>>>
>>> +CC Panto
>>
>> No; this is for different use.
>>
>> The open and close are to open the Boot partitions part of eMMC 4; by
>> default those eMMC will be using the user partitions, not the boot
>> area.
>>
>> The nice, and confusing thing, is that those boot partitions also
>> start in address 0 as a 'virtual disk'.
>
> I don't think they are different commands that do the same by coincidence. The 'mmc dev' command, when passed a fourth argument for the partition is calling the function 'mmc_switch_part()'.
> This function executes the CMD6 command to write the Extended CSD register PARTITION_CONFIG field that gives you access to any MMC partition (user data area, boot partitions 1 and 2, RPMB, General Purpose 1-4 partitions).
>
> It doesn't look like specific eMMC commands are needed to access the boot partitions, but maybe I'm misinterpreting the code.
Well, I think also your opinion. This code is the same behavior.
I didn't find any difference...
Best Regard,
Jaehoon Chung
>
> Best regards,
> --
> Hector Palacios
> _______________________________________________
> U-Boot mailing list
> U-Boot at lists.denx.de
> http://lists.denx.de/mailman/listinfo/u-boot
>
prev parent reply other threads:[~2014-01-09 8:45 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-02 16:53 [U-Boot] Are mmc open/close subcommands needed? Hector Palacios
2014-01-02 23:36 ` Marek Vasut
2014-01-03 17:35 ` Otavio Salvador
2014-01-07 7:47 ` Hector Palacios
2014-01-09 8:45 ` Jaehoon Chung [this message]
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