[PATCH] mmc: sdhci: add support for pre_req and post_req

[Jaehoon Chung]

Hi Shawn

I tested using ADMA with your patch...(benchmark : IOzone)
But I didn't get improvement of performance with ADMA..
(i can see improvement of performance with SDMA)

I want to know how you think about this..

Regards,
Jaehoon Chung

Andrei Warkentin wrote:
> Hi Shawn,
> 
> On Sat, Apr 16, 2011 at 11:48 AM, Shawn Guo <shawn.guo at linaro.org> wrote:
>> pre_req() runs dma_map_sg() post_req() runs dma_unmap_sg.
>> If not calling pre_req() before sdhci_request(), request()
>> will prepare the cache just like it did it before.
>> It is optional to use pre_req() and post_req().
>>
>> Signed-off-by: Shawn Guo <shawn.guo at linaro.org>
>> ---
>> I worked out the patch by referring to Per's patch below.
>>
>>  omap_hsmmc: add support for pre_req and post_req
>>
>> It adds pre_req and post_req support for sdhci based host drivers to
>> work with Per's non-blocking optimization.  But I only have imx esdhc
>> based hardware to test.  Unfortunately, I can not measure the
>> performance gain using mmc_test, because the current esdhc driver on
>> mainline fails on the test.  So I just did a quick test using 'dd',
>> but sadly, I did not see noticeable performance gain here.  The
>> followings are possible reasons I can think of right away.
>>
>> * The patch did not add pre_req and post_req correctly.  Please help
>>  review to catch the mistakes if any.
>> * The imx esdhc driver uses SDHCI_SDMA (max_segs is 1) than SDHCI_ADAM
>>  (max_segs is 128), due to the broken ADMA support on imx esdhc.  So
>>  can people holding other sdhci based hardware give a try on the
>>  patch?
>>
>> Hopefully, I can find some time to have a close look at the mmc_test
>> failure and the broken ADMA with imx esdhc.
>>
> 
> I'll try it out...
> 
> A
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