Re: [PATCH v3 2/2] DMAEngine: Add DMAEngine driver based on old MSMDMA APIs

[David Brown]

On Tue, Mar 13, 2012 at 04:27:37PM +0530, Shantanu Gupta wrote:

> Any info available(publicly) on so as to what all chipsets have this capability
> ?

The ADM hardware is in every currently available MSM that can run
Linux.  It is being phased out, to be replaced by a new DMA system
(SPS/BAM).  Fortunately, there are some chips (MSM8960) that have both
ADM and SPS/BAM so there should be time to get those drivers in.

At least as my memory serves me:

  7201 - ADM
  8250 - ADM
  8660 - 2 ADMs, SPS/BAM
  8960 - 1 ADM, SPS/BAM

The ADM is mostly a regular DMA-type device.  Each channel can be
associated with a rate-control channel, which is needed for some
devices.  It also has a mode called "box mode", which works kind of
like a self-repeating scatter list.  This mode is needed for some of
the peripherals also on the MSM.

David

> On Tue, Mar 13, 2012 at 1:44 AM, Daniel Walker <dwalker@xxxxxxxxxx> wrote:
> 
>     On Mon, Mar 12, 2012 at 04:02:44PM +0530, Ravi Kumar V wrote:
>     > Add DMAEngine based driver using the old MSM DMA APIs internally.
> 
>     What do you mean by this?
> 
>     > The benefit of this approach is that not all the drivers
>     > have to get converted to DMAEngine APIs simultaneosly while
>     > both the drivers can stay enabled in the kernel. The client
>     > drivers using the old MSM APIs directly can now convert to
>     > DMAEngine one by one.
> 
>     Which drivers?
>    
>     Daniel
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> 

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