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Message-ID: <74d0deb30807282330y142cedd2ld0ecf33cc459a75a@mail.gmail.com>
Date: Tue, 29 Jul 2008 08:30:09 +0200
From: "pHilipp Zabel" <philipp.zabel@...il.com>
To: "Uli Luckas" <u.luckas@...d.de>
Cc: LKML <linux-kernel@...r.kernel.org>,
"Marek Vasut" <marek.vasut@...il.com>, drzeus-mmc@...eus.cx
Subject: Re: [PATCH] fix misalignment in pxamci
On Mon, Jul 28, 2008 at 6:23 PM, Uli Luckas <u.luckas@...d.de> wrote:
> On Saturday, 5. July 2008, pHilipp Zabel wrote:
>> On Sat, Jul 5, 2008 at 2:19 AM, Marek Vasut <marek.vasut@...il.com> wrote:
>> > Hi,
>> > Philipp Zabel finally made the pxamci issue clear. It turned out, that
>> > pxamci needs the DMA destination address to be aligned to 8 bytes. In
>> > some cases it happened, that the address was aligned to 4 bytes causing
>> > controller to incorrectly transfer data (and resulting into error like
>> > "mmc0: unrecognised SCR structure version 1"). The following patch allows
>> > to debug this issue and moreover fixes it by moving one 4 byte entry of
>> > mmc_card structure, aligning the DMA destination back to 8 bytes.
>> >
>> > Signed-off-by: Marek Vasut <marek.vasut@...il.com>
>>
>> We can enable byte aligned transfers on the DMA controller. This is
>> what I came up with yesterday:
>> (sorry for wrapped lines - the proper patch should probably be a
>> combination of both
>> warning/DALGN handling and and moving something in mmc_card around).
>>
> Hi Philipp,
> this driver is not only for pxa27x but for pxa25x as well and pxa25x can't
> handle unaligned DMA.
> Shouldn't Marek Vasut's patch be included for the PXA25x case?
Argh, DALGN shouldn't be defined in pxa-regs.h. We really need an
aligned SCR target then. Pierre, is there any way we can have the MMC
core align DMA targets for pxa25x?
Just moving elements of the mmc_card structure around seems to be good
enough, but I fear this will break again as soon as the next person
forgets about pxamci's special needs on pxa25x.
regards
Philipp
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