Re: Unale to get MTD device info

[Radha Mohan <radhamohan_ch@yahoo.com>]

Hi,

Even I do not know many things regarding your queries but I will try to tell what I know. Maybe someone from this group can add.

>I thought Flashes are block devices. How come we treat this as char 
>devices? Why should we treat as char device?
To mount a filesystem and all you need the devices as block device so I think mtdblock is for this. Using char device method you can directly
control the MTD device like a RAM and there are some ioctls. But I think the read,write calls will of both will be eventually calling underlying MTD device
driver's read and write.

>why minor mumber should be incremented by  2?
  I do not know why the minor number is increment by 2. Maybe this is how it is in the char implementation inside kernel

>What happens when we do a mknod /dev/mtd0 c 90 0?
   this is how we create device nodes for any device type in linux. Search about this in google.

>Do we need to do anything with the /dev/mtdblock0 while erasing and 
>reflashing ?
 I do not think so.

-- Mohan



----- Original Message ----
From: Rahanesh <rahanesh@tataelxsi.co.in>
To: Radha Mohan <radhamohan_ch@yahoo.com>
Cc: linux-mtd@lists.infradead.org
Sent: Monday, 24 August, 2009 3:20:02 PM
Subject: Re: Unale to  get MTD device info

Hi Mohan,

That was really very helpful..

After doing this i am nw able to erase flash.

Few doubts:

I thought Flashes are block devices. How come we treat this as char 
devices? Why should we treat as char device?

why minor mumber should be incremented by  2?

What happens when we do a mknod /dev/mtd0 c 90 0?

Do we need to do anything with the /dev/mtdblock0 while erasing and 
reflashing ?

Thanks
Rahanesh


Radha Mohan wrote:
> Hi,
>
> Create char mtd devices
>
> mknod /dev/mtd0 c 90 0
> mknod /dev/mtd1 c 90 2
> ..
> ..
> Note that the minor number increments by 2.
> Before that you will need to confirm whether CONFIG_MTD_CHAR is set in your kernel or not. This will enable char device access
> to your mtdblock device. Or else you will not be able to write to mtd0 char device.
>
> You can erase and copy anything to the mtd devices. You can use "flashcp" from the mtd-utils. Else you can write your own code to write to
> the flash. You can take help of the flashcp code in mtd-utils. 
>
> -- Mohan
>
> ________________________________
> From: Rahanesh <rahanesh@tataelxsi.co.in>
> To: Radha Mohan <radhamohan_ch@yahoo.com>
> Cc: linux-mtd@lists.infradead.org
> Sent: Monday, 24 August, 2009 12:35:42 PM
> Subject: Re: Unale to  get MTD device info
>
> Hi Radha Mohan ,
>
> Thanks a lot for responding.
>
> I have few doubts regarding your reply.
>
> In the /dev/ partition of Linux i cannot see any mtd char device.. Only 
> mtdblock is there.
>
> Can i convert the block devices to character devices? if so how?
>
> Is it possible for me to erase mtdblock0 and copy to mtdblock0 using any 
> other utilities?
>
> I am a newbie to all this. Please give your valuable suggestions
>
> Thanks
> Rahanesh
>
>
> Radha Mohan wrote:
>  
>> hi rahanesh,
>>
>> The mtd-utils do not work on block devices like mtdblock0. Use mtd0 
>> instead. The mtd0 is char device of mtdblock0.
>>
>> -- Mohan
>>
>> ------------------------------------------------------------------------
>> *From:* Rahanesh <rahanesh@tataelxsi.co.in>
>> *To:* linux-mtd@lists.infradead.org
>> *Sent:* Monday, 24 August, 2009 10:53:06 AM
>> *Subject:* Unale to get MTD device info
>>
>> Hi all,
>>
>> I have four mtdblocks in my flash .
>> mtdblock0 -> Primary bootloader
>> mtdblock1 -> uboot
>> mtdblock2 -> JFFS
>> mtdbloack3-> config
>>
>> During Linux booting , it mounts mtdblock2 to a temp folder which can 
>> be seen as a part of ramdisk(root file system of linux)
>>
>> Now from Linux i need to flash a new jffs image to mtdblock2 itself.
>>
>> With the support from this mailing list i have copied mtd-utilities 
>> package into Linux. Now i have flash_eraseall and flash_cp commands.
>>
>> But when i run flash_eraseall  i gett the following error
>>
>>
>> flash_eraseall: /dev/mtdblock1: *unable to get MTD device info
>>
>> *Please help on this!!!!!!!
>>
>> Thanks
>> Rahanesh
>>
>>
>>
>>
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