From: Christoph Hellwig <hch@lst.de>
To: Huacai Chen <chenhc@lemote.com>
Cc: James Hogan <jhogan@kernel.org>, Christoph Hellwig <hch@lst.de>,
Ralf Baechle <ralf@linux-mips.org>,
"Steven J . Hill" <Steven.Hill@cavium.com>,
Linux MIPS Mailing List <linux-mips@linux-mips.org>,
Fuxin Zhang <zhangfx@lemote.com>,
Zhangjin Wu <wuzhangjin@gmail.com>,
Jayachandran C <jchandra@broadcom.com>
Subject: Re: [PATCH 2/2] MIPS: Loongson64: Add cache_sync to loongson_dma_map_ops
Date: Fri, 26 Jan 2018 08:56:12 +0100 [thread overview]
Message-ID: <20180126075612.GD2356@lst.de> (raw)
In-Reply-To: <CAAhV-H7i8PZtn7JMgzCW3nseH-rwtcc_H6_9n+pOE4DU5i1KAg@mail.gmail.com>
On Thu, Jan 25, 2018 at 04:44:36PM +0800, Huacai Chen wrote:
> Yes, kmalloc()'d memory with the appropriate GFP_DMA flags can be
You should never use GFP_DMA in kmalloc calls in new code.
> synced using the dma_map_*() and dma_unmap_*() functions. So,
> loongson_dma_map_page()/loongson_dma_unmap_page() (which is the
> backend of dma_map_*() and dma_unmap_*()) should call dma_cache_sync()
> for non-coherent devices, right?
No, it should call the internal dma sync for device/cpu calls, as already
explained by James. Note that for 4.17 or 4.18 I plan to extent
the dma-direct work to not dma coherent systems, so we'll get an
explicit and document ABI for those across platforms. That is if
I can pull it off as it doesn't seem entirely trivial.
prev parent reply other threads:[~2018-01-26 7:56 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-16 8:35 [PATCH 2/2] MIPS: Loongson64: Add cache_sync to loongson_dma_map_ops Huacai Chen
2018-01-24 14:02 ` James Hogan
2018-01-24 14:11 ` Christoph Hellwig
2018-01-24 15:03 ` James Hogan
2018-01-24 15:29 ` Christoph Hellwig
2018-01-25 7:09 ` Huacai Chen
2018-01-25 7:55 ` James Hogan
2018-01-25 8:44 ` Huacai Chen
2018-01-25 10:54 ` James Hogan
2018-01-25 11:04 ` Huacai Chen
2018-01-25 12:31 ` James Hogan
2018-01-26 7:56 ` Christoph Hellwig [this message]
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=20180126075612.GD2356@lst.de \
--to=hch@lst.de \
--cc=Steven.Hill@cavium.com \
--cc=chenhc@lemote.com \
--cc=jchandra@broadcom.com \
--cc=jhogan@kernel.org \
--cc=linux-mips@linux-mips.org \
--cc=ralf@linux-mips.org \
--cc=wuzhangjin@gmail.com \
--cc=zhangfx@lemote.com \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.