From: Peter Ujfalusi <peter.ujfalusi@ti.com>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: vinod.koul@intel.com, Tony Lindgren <tony@atomide.com>,
grant.likely@linaro.org, dmaengine@vger.kernel.org,
linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
robh+dt@kernel.org, nm@ti.com
Subject: Re: [PATCH 5/6] dmaengine: omap-dma: Remove mapping between virtual channels and requests
Date: Tue, 24 Feb 2015 19:01:41 +0200 [thread overview]
Message-ID: <54ECAE75.3070501@ti.com> (raw)
In-Reply-To: <20150224142833.GI8670@n2100.arm.linux.org.uk>
On 02/24/2015 04:28 PM, Russell King - ARM Linux wrote:
> On Tue, Feb 24, 2015 at 04:21:22PM +0200, Peter Ujfalusi wrote:
>> Do not direct map the virtual channels to sDMA request number. When the
>> sDMA is behind of a crossbar this direct mapping can cause situations when
>> certain channel can not be requested since the crossbar request number
>> will no longer match with the sDMA request line.
>> The direct mapping for virtual channels with HW request lines will make it
>> harder to implement MEM_TO_MEM mode for the driver.
>
> I assume when you talk about MEM_TO_MEM, you're referring to a DMA_MEMCPY
> driver.
>
> mem2mem should not be handled by the slave driver. This should be a
> separate DMA engine driver structure which does not have DMA_SLAVE set.
>
> See how amba-pl08x handles this.
Thanks for the pointer. I'm just planning to add the DMA_MEMCPY support for
omap-dma. With that in place we can convert the remaining legacy API users to
use dmaengine (as I recall all of them are using DMA for memcopy)
--
Péter
next prev parent reply other threads:[~2015-02-24 17:01 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-24 14:21 [PATCH 0/6] dmaengine/dra7x: DMA router (crossbar support) Peter Ujfalusi
2015-02-24 14:21 ` [PATCH 1/6] dmaengine: of_dma: Support for DMA routers Peter Ujfalusi
2015-02-24 14:21 ` [PATCH 2/6] dmaengine: Add driver for TI DMA crossbar on DRA7x Peter Ujfalusi
2015-02-28 16:00 ` Paul Bolle
2015-03-02 7:57 ` Peter Ujfalusi
2015-02-24 14:21 ` [PATCH 3/6] dmaengine: omap-dma: Use defines for dma channels and request count Peter Ujfalusi
2015-02-24 14:21 ` [PATCH 4/6] dmaengine: omap-dma: Take DMA request number from DT if it is available Peter Ujfalusi
2015-02-24 14:25 ` Russell King - ARM Linux
2015-02-24 14:28 ` Peter Ujfalusi
2015-02-24 14:21 ` [PATCH 5/6] dmaengine: omap-dma: Remove mapping between virtual channels and requests Peter Ujfalusi
[not found] ` <1424787683-19151-6-git-send-email-peter.ujfalusi-l0cyMroinI0@public.gmane.org>
2015-02-24 14:28 ` Russell King - ARM Linux
2015-02-24 17:01 ` Peter Ujfalusi [this message]
2015-02-24 14:21 ` [PATCH 6/6] ARM: DTS: dra7x: Integrate sDMA crossbar Peter Ujfalusi
2015-03-09 13:14 ` [PATCH 0/6] dmaengine/dra7x: DMA router (crossbar support) Peter Ujfalusi
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=54ECAE75.3070501@ti.com \
--to=peter.ujfalusi@ti.com \
--cc=devicetree@vger.kernel.org \
--cc=dmaengine@vger.kernel.org \
--cc=grant.likely@linaro.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-omap@vger.kernel.org \
--cc=linux@arm.linux.org.uk \
--cc=nm@ti.com \
--cc=robh+dt@kernel.org \
--cc=tony@atomide.com \
--cc=vinod.koul@intel.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 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).