From: Joerg Roedel <joro@8bytes.org>
To: Tejun Heo <tj@kernel.org>
Cc: Shuah Khan <shuah.kh@samsung.com>,
Eli Billauer <eli.billauer@gmail.com>,
devel@driverdev.osuosl.org, gregkh@linuxfoundation.org,
bhelgaas@google.com, linux-kernel@vger.kernel.org,
linux-pci@vger.kernel.org, iommu@lists.linux-foundation.org,
discuss@x86-64.org
Subject: Re: [PATCH v2 1/4] dma-mapping: Add devm_ interface for dma_map_single()
Date: Wed, 4 Jun 2014 16:12:11 +0200 [thread overview]
Message-ID: <20140604141211.GC23880@8bytes.org> (raw)
In-Reply-To: <20140604140408.GC5004@htj.dyndns.org>
On Wed, Jun 04, 2014 at 10:04:08AM -0400, Tejun Heo wrote:
> Hmmm? Don't we have drivers which map dma buffers on device init and
> release them on exit? For dynamic usages, its usefulness is limited
> especially given that dynamic tracking of buffers usually would
> involve tracking of other information too in addition to dma buffer
> pointer themselves. If alloc on init and free on exit is a very rare
> usage pattern, I have no objection against not adding devm interface
> for dma mappings.
Yes, but those drivers usually get DMA buffers at init time with the
dma_alloc_* interfaces. The dma_map_* interfaces discussed here belong
to the streaming DMA-API, so they are usually used for only one DMA
transaction before dma_unmap_* is called on them.
A devm interface for the dma_alloc_* family of functions would
actually make sense, but not for the dma_map_* functions.
Joerg
next prev parent reply other threads:[~2014-06-04 14:12 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-01 7:01 [PATCH v2 0/4] devres: dma-mapping: Introducing new functions Eli Billauer
2014-06-01 7:01 ` [PATCH v2 1/4] dma-mapping: Add devm_ interface for dma_map_single() Eli Billauer
2014-06-03 21:24 ` Shuah Khan
2014-06-03 23:39 ` Joerg Roedel
2014-06-04 14:04 ` Tejun Heo
2014-06-04 14:12 ` Joerg Roedel [this message]
2014-06-04 14:14 ` Tejun Heo
2014-06-04 15:03 ` Eli Billauer
2014-06-04 21:25 ` Joerg Roedel
2014-06-06 11:45 ` Eli Billauer
2014-06-06 16:01 ` Greg KH
2014-06-06 16:21 ` Eli Billauer
2014-06-06 17:02 ` Shuah Khan
2014-06-07 11:23 ` Eli Billauer
2014-06-01 7:01 ` [PATCH v2 2/4] dma-mapping: Add devm_ interface for dma_map_single_attrs() Eli Billauer
2014-06-01 7:01 ` [PATCH v2 3/4] dma-mapping: pci: Add devm_ interface for pci_map_single Eli Billauer
2014-06-01 7:01 ` [PATCH v2 4/4] staging: xillybus: Use devm_ API for memory allocation and DMA mapping Eli Billauer
Reply instructions:
You may reply publicly 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=20140604141211.GC23880@8bytes.org \
--to=joro@8bytes.org \
--cc=bhelgaas@google.com \
--cc=devel@driverdev.osuosl.org \
--cc=discuss@x86-64.org \
--cc=eli.billauer@gmail.com \
--cc=gregkh@linuxfoundation.org \
--cc=iommu@lists.linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=shuah.kh@samsung.com \
--cc=tj@kernel.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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).