linux-kernel - Re: [PATCH 2/2] MEMSTICK: Add driver for Ricoh R5C592 Card reader.

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Date:	Sat, 07 Aug 2010 23:22:45 +0300
From:	Maxim Levitsky <maximlevitsky@...il.com>
To:	Alex Dubov <oakad@...oo.com>
Cc:	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] MEMSTICK: Add driver for Ricoh R5C592 Card reader.

Hi,

I have few more questions about memsticks.

First of all, I need an explanation of overwrite flag.
You already explained it to me once, but I still not sure about few
things.

#define MEMSTICK_OVERWRITE_UDST  0x10
This one I understand, thinking about xD again, I think it is very
handy.

My idea (from xD of course) is that copyonwrite is done this way:

1. read old sector
2. allocate new sector
2. write what was just read to new sector.
3. erase old sector.

Could you explain when I need to set and reset the
MEMSTICK_OVERWRITE_UDST?

#define MEMSTICK_OVERWRITE_PGST1 0x20
#define MEMSTICK_OVERWRITE_PGST0 0x40
I suppose these indicate that page(sector) contains incorrect data, just
like in xD there is page status?
Again, better explanation is welcome.
Also, should I touch that flag when I update sector?

#define MEMSTICK_OVERWRITE_BKST  0x80
This marks bad blocks?

Another question is about write of oob data.
When I write it, overwrite flag is updated, or I need to use
MEMSTICK_CP_OVERWRITE to update it?
I think former is true.

When I write a sector, I just write 0 to management flag, right?

And last question,
If I use MEMSTICK_CP_BLOCK, can I start reading a block from non-zero
page offset?

And surely last question, what is 'MS_CMD_BLOCK_END'

Thanks again for all help so far,

Best regards,
Maxim Levitsky

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