[PATCH] mmc: sdhci: add support for pre_req and post_req
jh80.chung at samsung.com
Tue Apr 26 01:26:01 UTC 2011
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..
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
>> 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...
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