Messages in this thread |  | | Date | Sat, 02 Feb 2013 23:06:06 +0400 | From | Sergei Shtylyov <> | Subject | Re: [PATCH v7 01/10] ARM: davinci: move private EDMA API to arm/common |
| |
Hello.
On 02-02-2013 22:07, Matt Porter wrote:
>>>>>>> Move mach-davinci/dma.c to common/edma.c so it can be used >>>>>>> by OMAP (specifically AM33xx) as well.
>>>>>> I think this should rather go to drivers/dma/?
>>>>> No, this is the private EDMA API. It's the analogous thing to >>>>> the private OMAP dma API that is in plat-omap/dma.c. The actual >>>>> dmaengine driver is in drivers/dma/edma.c as a wrapper around >>>>> this...same way OMAP DMA engine conversion is being done.
>>>> Keeps me wondering why we couldn't have the same with CPPI 4.1 when I proposed >>>> that, instead of waiting indefinitely for TI to convert it to drivers/dma/ >>>> directly. We could have working MUSB DMA on OMAP-L1x/Sitara all this time... Sigh.
>>> That is a shame. Yeah, I've pointed out that I was doing this exactly >>> the same way as was acceptable for the OMAP DMA conversion since it was >>> in RFC. The reasons are sound since in both cases, we have many drivers >>> to convert that need to continue using the private DMA APIs.
>> In case of CPPI 4.1, we'd only have to convert MUSB DMA driver. Other >> in-tree CPPI 4.1 having SoCs don't use it for anything but MUSB -- it even is >> sub-block of their MUSB device, AFAIK (I maybe wrong about Sitaras -- I don't >> know them well).
> Well, it's pretty clear to me now that there's good reason for it not > landing in arch/arm/ so the obvious path is to do the dmaengine > conversion and put it in drivers/dma/ if it's really a generic dma engine. > I'm not sure why you express concern over the dma engine api not fitting > with CPPI 4.1?
It's not a DMA controller only, it's 3 distinct devices, with the DMA controller being one among them and using another one, the queue manager, as some sort of proxy. The third device doesn't exist on OMAP-L1x SoCs -- it's the buffer manager.
> If it doesn't work, work with Vinod to fix the api. It's > expected, I'm working on dmaengine API changes right now to deal with a > limitation of EDMA that needs to be abstracted.
Sorry, now it's TI's task. I no longer have time to work on this (my internal project to push OMAP-L1x support upstream has expired at Sep 2010) and my future in MV is very uncertain at this moment. Most probably I'll leave it (or be forced to leave).
> As pointed out, edma.c is already here in arch/arm/, so moving it doesn't > add something new. It does let us regression test all platforms that use it > (both Davinci and AM33xx) as I go through the conversion process.
Could have been the same with CPPI 4.1 in theory if it was added to mach-davinci/ back in 2009... we'd then only have to move it. EDMA code is much older of course, so it's probably more justified.
> -Matt
WBR, Sergei
|  |