Re: [PATCH v7 01/10] ARM: davinci: move private EDMA API to arm/common

Sergei Shtylyov
2013-02-01T23:10:24Z

Hello.

On 02-02-2013 0:56, Felipe Balbi wrote:

>>> good point, do you wanna send some patches ?

>> I have already sent them countless times and even stuck CPPI 4.1 support (in
>> arch/arm/common/cppi41.c) in Russell's patch system. TI requested to remove the
>> patch. :-(

> sticking into arch/arm/common/ wasn't a nice move.

Like with EDMA we have nothing else to do with CPPI 4.1 being shared by
DaVinci-like and OMAP-like SOCs. Thank TI for creatring this mess. And
actually even that is not a good place since I think I know of a MIPS SoC
having CPPI 4.1 as well, just out of tree.

> But then again, so
> wasn't asking for the patch to be removed :-s

Unfortunately, Russell has done it -- all that was discuseed without me in
the loop even. :-/

>>> I guess to make the MUSB side simpler we would need musb-dma-engine glue
>>> to map dmaengine to the private MUSB API. Then we would have some
>>> starting point to also move inventra (and anybody else) to dmaengine
>>> API.

>> Why? Inventra is a dedicated device's private DMA controller, why make
>> universal DMA driver for it?

> because it doesn't make sense to support multiple DMA APIs. We can check
> from MUSB's registers if it was configured with Inventra DMA support and
> based on that we can register MUSB's own DMA Engine to dmaengine API.

I still disagree. IMO drivers/dma/ is for standalone DMA engines. Else we
could stick every bus mastering device's DMA engines there. CPPI 4.1 is in
design standlone DMA engine, despite all in-tree implementations having it as
subblock of MUSB and serving only MUSB.

WBR, Sergei