Re: [PATCH] mmc: dw_mmc: Support predefined multiple block transfers.

Jaehoon Chung
2011-10-05T05:02:15Z

Hi Mr.Jeon

One question...if we used predefined transfer, didn't send stop-command?
then i think that didn't need to enter this condition..how about this?

In __dw_mci_start_reqeust() function(at your patch)

if (mrq->stop)
host->stop_cmdr = dw_mci_prepare_command(slot->mmc, mrq->stop);

If i misunderstood something, plz let me know...Thanks.

Tested-by: Jaehoon Chung <jh80.chung@samsung.com>

On 09/28/2011 05:23 PM, Seungwon Jeon wrote:

> Andrei Warkentin wrote:
>> 2011/9/26 Seungwon Jeon <tgih.jun@samsung.com>:
>>> Andrei Warkentin wrote:
>>>> Hi Seungwon,
>>>>
>>>> ----- Original Message -----
>>>>> From: "Seungwon Jeon" <tgih.jun@samsung.com>
>>>>> To: linux-mmc@vger.kernel.org
>>>>> Cc: "Chris Ball" <cjb@laptop.org>, linux-samsung-soc@vger.kernel.org,
>>>> "kgene kim" <kgene.kim@samsung.com>, "dh han"
>>>>> <dh.han@samsung.com>, "Seungwon Jeon" <tgih.jun@samsung.com>
>>>>> Sent: Monday, September 26, 2011 7:46:59 AM
>>>>> Subject: [PATCH] mmc: dw_mmc: Support predefined multiple block
>>>> transfers.
>>>>>
>>>>> This patch adds the support for predefined multiple block read/write.
>>>>>
>>>>> Signed-off-by: Seungwon Jeon <tgih.jun@samsung.com>
>>>>
>>>> Without knowing much about dw_mmc host, your logic otherwise looks ok,
>>>> given what
>>>> I've previously done for SDHCI as far as CMD23/Auto-CMD23 enhancement.
>>>> Just curious, what eMMC cards did you test this on, and what
>> improvement
>>>> did you see?
>>>
>>> Thank you for review.
>>> As you done, predefined transfer is required for reliable writes and
>> eMMC4.5 feature.
>>> Sadly, I didn't gain an improvement in my case.
>>> (I don't know whether I can clarify the tested eMMC card, just one
>> sample.)
>>>
>>
>> So far I've seen some Sandisk cards have a noticeable real-life
>> improvement (30%) over
>> open-ended transfers.
>>
>> You might wish to try out https://github.com/andreiw/superalign to be
>> certain.
>
> I had already tested this patch with IOZONE, but I found no difference.
> Maybe a result depends on eMMC device.
> As your recommend, I applied above benchmark tool.
> Predefined transfer seems like a little better, but there is no difference.
>
> Thanks.
> Seungwon Jeon.
>
>>
>> A
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