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

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Date:	Thu, 12 Aug 2010 00:22:43 -0700 (PDT)
From:	Alex Dubov <oakad@...oo.com>
To:	Maxim Levitsky <maximlevitsky@...il.com>
Cc:	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] MEMSTICK: Add driver for Ricoh R5C592 Card reader.

> Maximum I might need to clear page status bits, but I can
> do that later
> after I write the block.
> This won't be any performance impact because amount of bad
> pages
> shouldn't be normally greater that zero.
> (Otherwise there will be data loss...)

These things do degrade. I think, memsticks do write-verify, so bad blocks
will appear during write and can be marked as such without any data loss.

> 
> One interesting thing that I just want your opinion on is
> what to do
> with correctable errors.
> Common sense suggests to relocate the sector + and mark it
> bad.
> But I don't know how common such sectors are, and thus I
> could do more
> harm that good by marking too many sectors as bad.

I agree that number of writes to the media should be kept minimal.
So bad (in either way) blocks encountered should be logged, but not
touched, unless the error appears during an actual write/modify operation.

> 
> I hope I create ms_block.c soon, and put that old problem
> to the rest.

If you have time and desire, try to put a low level format option in - 
some function to erase all blocks, except the system ones.

> 
> As time permits I will also port your driver for xD portion
> of jMicron
> device (which I have).

By the way, I've got some errata for the newer JMicron chipsets. If they
have not contacted you yet, I'll forward it to you.

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