Re: [PATCH] libertas: if_sdio: fix buffer alignment in struct if_sdio_card

[Mike Rapoport <mike@compulab.co.il>]

Marek Vasut wrote:
> Dne Ne 22. srpna 2010 13:22:40 Mike Rapoport napsal(a):
>> The commit 886275ce41a9751117367fb387ed171049eb6148 (param: lock
>> if_sdio's lbs_helper_name and lbs_fw_name against sysfs changes)
>> introduced new fields into the if_sdio_card structure. It caused
>> missalignment of the if_sdio_card.buffer field and failure at driver
>> load time:
>>
>>   ~# modprobe libertas_sdio
>>   [   62.315124] libertas_sdio: Libertas SDIO driver
>>   [   62.319976] libertas_sdio: Copyright Pierre Ossman
>>   [   63.020629] DMA misaligned error with device 48
>>   [   63.025207] mmci-omap-hs mmci-omap-hs.1: unexpected dma status 800
>>   [   66.005035] libertas: command 0x0003 timed out
>>   [   66.009826] libertas: Timeout submitting command 0x0003
>>   [   66.016296] libertas: PREP_CMD: command 0x0003 failed: -110
>>
>> Adding explicit alignment attribute for the if_sdio_card.buffer field
>> fixes this problem.
>>
>> Signed-off-by: Mike Rapoport <mike@compulab.co.il>
>> ---
>>  drivers/net/wireless/libertas/if_sdio.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/net/wireless/libertas/if_sdio.c
>> b/drivers/net/wireless/libertas/if_sdio.c index ba854c7..87b6349 100644
>> --- a/drivers/net/wireless/libertas/if_sdio.c
>> +++ b/drivers/net/wireless/libertas/if_sdio.c
>> @@ -128,7 +128,7 @@ struct if_sdio_card {
>>  	bool			helper_allocated;
>>  	bool			firmware_allocated;
>>
>> -	u8			buffer[65536];
>> +	u8			buffer[65536] __attribute__((aligned(4)));
>>
>>  	spinlock_t		lock;
>>  	struct if_sdio_packet	*packets;
> 
> Will this work even on platforms that need some weird DMA destination address 
> alignment ? I might be totally off with this question though ;-)

I've tested it on PXA and OMAP and it works on both.
I think that on platforms with weird DMA destination address alignment 
libertas_sdio will fail anyway because of if_sdio_packet alignment.

> Cheers
> --
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-- 
Sincerely yours,
Mike.