From: Jassi Brar <jassisinghbrar@gmail.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>,
Stephen Warren <swarren@nvidia.com>,
Benoit Cousson <b-cousson@ti.com>,
Vinod Koul <vinod.koul@intel.com>,
devicetree-discuss@lists.ozlabs.org,
Nicolas Ferre <nicolas.ferre@atmel.com>,
rob.herring@calxeda.com, Grant Likely <grant.likely@secretlab.ca>,
Thomas Abraham <thomas.abraham@linaro.org>,
Dan Williams <dan.j.williams@intel.com>,
linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] of: Add generic device tree DMA helpers
Date: Mon, 19 Mar 2012 23:36:31 +0530 [thread overview]
Message-ID: <CABb+yY3cJZO_A+Z5vtOkyt5XEX7exhPk5ZG8Mm35n3DFryBk5w@mail.gmail.com> (raw)
In-Reply-To: <201203191611.59064.arnd@arndb.de>
On Mon, Mar 19, 2012 at 9:41 PM, Arnd Bergmann <arnd@arndb.de> wrote:
>
>> Secondly, there are platforms (Samsung) where peripherals are connected
>> to more than one DMA controller, and either DMA controller can be used -
>> I'm told by Jassi that there's reasons why you'd want to select one or
>> other as the target at runtime.
>
> How common is that? If there are only a few drivers that have this
> requirement, we could have this represented in the driver binding, by
> listing multiple channels and giving the device the choice.
>
All Samsung SoCs (last ~4yrs) with PL330 have some peripherals
that could be served by more than one PL330 instance.
The requirement is not from any driver and it is nothing Samsung specific.
Any platform with 1:n client:dmac might want to do stuff like serving
a new channel request from an already active DMAC, rather than
invoking otherwise fully idle one.
Similarly for Mem->Mem, the PL330 distributes its cycles between
active channels, so a platform might want channel allocation uniformly
across PL330 instances.
-jassi
next prev parent reply other threads:[~2012-03-19 18:06 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-27 17:29 [RFC PATCH 1/2] of: Add generic device tree DMA helpers Cousson, Benoit
2012-01-27 18:13 ` Stephen Warren
2012-01-27 20:36 ` Cousson, Benoit
2012-01-28 18:12 ` Grant Likely
2012-01-28 18:06 ` Grant Likely
2012-01-31 21:26 ` Cousson, Benoit
2012-02-02 4:52 ` Grant Likely
2012-01-31 23:09 ` Russell King - ARM Linux
2012-02-01 10:50 ` Cousson, Benoit
[not found] ` <4F2918F6.9040100-l0cyMroinI0@public.gmane.org>
2012-02-02 8:45 ` Russell King - ARM Linux
[not found] ` <20120202084539.GC1275-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
2012-02-02 8:54 ` Cousson, Benoit
2012-02-22 10:59 ` Nicolas Ferre
2012-02-23 10:03 ` Cousson, Benoit
2012-02-23 15:51 ` Nicolas Ferre
2012-02-23 15:57 ` Cousson, Benoit
[not found] ` <4F4661DE.90704-l0cyMroinI0@public.gmane.org>
2012-02-27 13:09 ` Nicolas Ferre
2012-02-27 14:22 ` Cousson, Benoit
2012-02-27 17:28 ` Nicolas Ferre
2012-02-29 14:54 ` [RFC PATCH] of: DMA helpers: manage generic requests specification Nicolas Ferre
2012-02-29 20:54 ` Stephen Warren
2012-03-05 13:14 ` Cousson, Benoit
2012-03-05 18:30 ` Stephen Warren
2012-03-05 19:57 ` Russell King - ARM Linux
2012-03-05 10:55 ` Cousson, Benoit
2012-03-05 15:36 ` Grant Likely
2012-03-14 17:47 ` Nicolas Ferre
2012-03-14 18:16 ` Stephen Warren
[not found] ` <4F22DEF2.5000807-l0cyMroinI0@public.gmane.org>
2012-03-15 8:38 ` [PATCH] of: Add generic device tree DMA helpers Nicolas Ferre
2012-03-15 9:22 ` Arnd Bergmann
2012-03-15 9:26 ` Russell King - ARM Linux
2012-03-15 10:09 ` Arnd Bergmann
2012-03-17 9:42 ` Grant Likely
2012-03-17 16:03 ` Arnd Bergmann
2012-03-18 9:08 ` Grant Likely
2012-03-15 10:27 ` Thierry Reding
2012-03-17 10:47 ` Grant Likely
2012-03-18 9:22 ` Thierry Reding
2012-03-18 15:10 ` Arnd Bergmann
2012-03-18 18:22 ` Grant Likely
2012-03-19 13:02 ` Mark Brown
2012-03-19 15:01 ` Arnd Bergmann
2012-03-19 15:07 ` Stephen Warren
2012-03-19 15:45 ` Arnd Bergmann
[not found] ` <201203191545.40933.arnd-r2nGTMty4D4@public.gmane.org>
2012-03-19 16:54 ` Stephen Warren
2012-03-15 16:30 ` Cousson, Benoit
2012-03-15 19:57 ` Russell King - ARM Linux
[not found] ` <20120315195753.GA2842-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
2012-03-15 20:41 ` Arnd Bergmann
2012-03-15 21:39 ` Cousson, Benoit
2012-03-15 21:55 ` Russell King - ARM Linux
2012-03-16 9:56 ` Arnd Bergmann
2012-03-20 14:02 ` Matt Porter
2012-03-15 23:45 ` Nicolas Pitre
2012-03-16 10:03 ` Arnd Bergmann
2012-03-16 11:19 ` Cousson, Benoit
2012-03-16 12:04 ` Arnd Bergmann
2012-03-16 13:28 ` Cousson, Benoit
2012-03-16 13:36 ` Nicolas Ferre
2012-03-17 9:40 ` Grant Likely
2012-03-18 20:13 ` Arnd Bergmann
2012-03-18 20:44 ` Grant Likely
2012-03-18 21:58 ` Arnd Bergmann
2012-03-18 22:12 ` Arnd Bergmann
2012-03-19 13:37 ` Nicolas Ferre
2012-03-19 15:20 ` Russell King - ARM Linux
2012-03-19 15:58 ` Cousson, Benoit
2012-03-19 13:30 ` Nicolas Ferre
2012-03-19 14:06 ` Arnd Bergmann
2012-03-19 15:33 ` Russell King - ARM Linux
2012-03-19 16:11 ` Arnd Bergmann
2012-03-19 18:06 ` Jassi Brar [this message]
2012-03-19 16:31 ` Nicolas Ferre
2012-03-19 17:49 ` Cousson, Benoit
2012-03-19 14:45 ` Grant Likely
2012-03-20 14:54 ` Nicolas Ferre
2012-03-20 10:13 ` [PATCH v2 1/2] " Nicolas Ferre
2012-03-20 10:13 ` [PATCH 2/2] of: selftest/dma: Add selftest for new DT DMA request helpers Nicolas Ferre
2012-03-20 14:16 ` Grant Likely
2012-03-20 10:17 ` [PATCH] of: dma/fixup Nicolas Ferre
[not found] ` <6b5dc1fadfd03a48093338b6981c0a7ae7662212.1332237596.git.nicolas.ferre-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org>
2012-03-20 13:03 ` [PATCH v2 1/2] of: Add generic device tree DMA helpers Arnd Bergmann
2012-03-20 15:38 ` Stephen Warren
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