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

Seungwon Jeon
2011-10-05T08:02:03Z

Jaehoon Chung wrote:
>
> 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.
Yes, predefined transfer doesn't send stop command normally.
But if transfer error is occurred, stop command is required.

Thank you for test.
Best regards,
Seungwon Jeon.
>
> 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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