From mboxrd@z Thu Jan  1 00:00:00 1970
From: b32955@freescale.com (Huang Shijie)
Date: Wed, 20 Jul 2011 10:18:26 +0800
Subject: [i.MX28 GPMI] problem overwriting all-0xff data in NAND
In-Reply-To: <20110719133602.GJ1951@pengutronix.de>
References: <20004.12663.29494.339601@ipc1.ka-ro>
	<20110718164354.GA3328@S2100-06.ap.freescale.net>
	<4E24E804.10002@freescale.com>
	<20005.7677.145955.789329@ipc1.ka-ro>
	<4E252C51.8070900@freescale.com>
	<20005.21635.427202.49313@ipc1.ka-ro> <20110719133602
Message-ID: <4E263AF2.60103@freescale.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

Hi Wolfram:
>>>>> I am debugging the DMA bug now. and I will send it out when i fix it.
>>>>>
>>>> What sort of DMA bug?
>>>>
>>> The DMA may time-out. :(
>>>
>>> The DMA time-out may occur in two situations:
>>> [1] send a command DMA descriptor, see the nfc->send_command() function.
>>> [2] read the non-ecc data from nand, see the nfc->read_data() function.
>>>
>>> I don't know why. Maybe caused by the timing, or something else.
> I am confused. The send-command DMA timeout prevents any write for me.
> You guys surely would have noticed if you have been bitten as well. Does
> it depend on the NAND chip?
I think It does not depend on the NAND chip.
My test chip is Samsung K9G8G08U0M.
Sometimes, I can run a long time while there is no DMA timeout occurring;
Sometimes, the bug appears right away.


>> Maybe you are missing this patch:
>> http://lists.infradead.org/pipermail/linux-arm-kernel/2011-April/049105.html
>> I sent it in April, but apparently it has not been integrated in
>> mainline or the pengutronix git.
> Well, just resend them; might be worth trying Shawn's comment, too (if
> that reset is really needed). BTW they didn't help for my case :(
I also tested the patch. It did not work too.

Best Regards
Huang Shijie
> Regards,
>
>     Wolfram
>