Linux-Block Archive on lore.kernel.org
 help / color / Atom feed
From: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Jun Nie <jun.nie@linaro.org>,
	"ulf.hansson@linaro.org" <ulf.hansson@linaro.org>,
	"robh+dt@kernel.org" <robh+dt@kernel.org>,
	"mark.rutland@arm.com" <mark.rutland@arm.com>,
	"adrian.hunter@intel.com" <adrian.hunter@intel.com>,
	"linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	"linux-ide@vger.kernel.org" <linux-ide@vger.kernel.org>
Subject: Re: [PATCH 4/4] mmc: sdhci: Add DMA memory boundary workaround
Date: Wed, 4 Dec 2019 07:11:04 +0000
Message-ID: <20191204145709.34e42f56@xhacker.debian> (raw)
In-Reply-To: <20191203130609.GA2144@infradead.org>

Hi Christoph

On Tue, 3 Dec 2019 05:06:09 -0800 Christoph Hellwig wrote:


> 
> On Tue, Dec 03, 2019 at 09:49:49AM +0000, Jisheng Zhang wrote:
> > > As in exactly one boundary and not an alignment?  Where the one
> > > boundary is not a power of two and thus can't be expressed?  
> >
> > Take drivers/mmc/host/sdhci-of-dwcmshc.c for example, target physical DMA addr
> > can't span 128MB, 256MB, 128*3MB, ...128*nMB
> >
> > I'm not sure whether blk_queue_segment_boundary could solve this limitation.  
> 
> That is exaxtly the kind of limitation blk_queue_segment_boundary is
> intended for.

Until after dma_map_sg(), we can't know the physical DMA address range, so
how does block layer know and check the DMA range beforehand? I'm a newbie on
block layer, could you please teach me? At the same time
I'm reading the code as well.

Thanks in advance


      reply index

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20191202144104.5069-1-jun.nie@linaro.org>
     [not found] ` <20191202144104.5069-5-jun.nie@linaro.org>
     [not found]   ` <20191203103320.273a7309@xhacker.debian>
     [not found]     ` <CABymUCMVi_N2Mt82YDt7wrys4Z_vnXYEu15-YBa+S1CejT9iZw@mail.gmail.com>
     [not found]       ` <20191203165123.4e6f9e28@xhacker.debian>
2019-12-03  9:18         ` Christoph Hellwig
2019-12-03  9:49           ` Jisheng Zhang
2019-12-03 13:06             ` Christoph Hellwig
2019-12-04  7:11               ` Jisheng Zhang [this message]

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20191204145709.34e42f56@xhacker.debian \
    --to=jisheng.zhang@synaptics.com \
    --cc=adrian.hunter@intel.com \
    --cc=devicetree@vger.kernel.org \
    --cc=hch@infradead.org \
    --cc=jun.nie@linaro.org \
    --cc=linux-block@vger.kernel.org \
    --cc=linux-ide@vger.kernel.org \
    --cc=linux-mmc@vger.kernel.org \
    --cc=mark.rutland@arm.com \
    --cc=robh+dt@kernel.org \
    --cc=ulf.hansson@linaro.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-Block Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-block/0 linux-block/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-block linux-block/ https://lore.kernel.org/linux-block \
		linux-block@vger.kernel.org
	public-inbox-index linux-block

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-block


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git