From: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
To: Matthew Leon <matthewleon@linux.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>,
Ulf Hansson <ulf.hansson@linaro.org>,
linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH mmc-next v3 3/3] mmc: sdhci-of-dwcmshc: solve 128MB DMA boundary limitation
Date: Mon, 30 Jul 2018 11:11:33 +0800 [thread overview]
Message-ID: <20180730111133.0b4e8b2d@xhacker.debian> (raw)
In-Reply-To: <01010164e92bcc1a-c3ac69eb-f6e5-4420-ac87-de1a0ffd0ac5-000000@us-west-2.amazonses.com>
On Mon, 30 Jul 2018 03:11:59 +0000
Matthew Leon <matthewleon@linux.com> wrote:
> >> Hey Jisheng,
>
> >Hi,
>
> >>
>
> >In LKML, we'd better not top post.
>
> Noted. My apologies.
>
> >> Shouldn't we be splitting until all DMA blocks are less than 128M
> boundary?
> >> I am a noob, but I think we should be prepared for boundaries that when
> >> split in two, will still be greater than 128M. Feel free to disagree but
> >> please explain why I may be wrong. Thank-you.
>
> >the limitation is "DMA addr can't span 128MB boundary" rather than "must be
> >less than 128MB", they are different.
>
> >And the max transfer size of one DMA desc is 64KB.
>
> >thanks
>
> I have misspoken. What if the DMA transfer size is 1024M? If we split in
> two, then we have 2 transfers, each of which span 512M. So wouldn't we need
> to split again to have 4 transfers, each of which span 128M?
>
the max transfer size of each desc is 64KB, how could it be 1024MB?
next prev parent reply other threads:[~2018-07-30 3:14 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-30 2:42 [PATCH mmc-next v3 0/3] solve SDHCI DWC MSHC 128MB DMA boundary limitation Jisheng Zhang
2018-07-30 2:45 ` [PATCH mmc-next v3 2/3] mmc: sdhci: introduce adma_write_desc() hook to struct sdhci_ops Jisheng Zhang
2018-08-15 14:07 ` Adrian Hunter
2018-07-30 2:46 ` [PATCH mmc-next v3 3/3] mmc: sdhci-of-dwcmshc: solve 128MB DMA boundary limitation Jisheng Zhang
[not found] ` <01010164e91d7bda-aa616cbf-7bb2-4fe4-85e5-a18e16433fde-000000@us-west-2.amazonses.com>
2018-07-30 2:59 ` Jisheng Zhang
[not found] ` <01010164e92bcc1a-c3ac69eb-f6e5-4420-ac87-de1a0ffd0ac5-000000@us-west-2.amazonses.com>
2018-07-30 3:11 ` Jisheng Zhang [this message]
2018-08-09 2:27 ` [PATCH mmc-next v3 0/3] solve SDHCI DWC MSHC " Jisheng Zhang
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