[RFC PATCH 2/5] dmaengine: allow sun6i-dma for more SoCs

[Andre Przywara]

On 24/11/16 10:55, Maxime Ripard wrote:
> On Thu, Nov 24, 2016 at 05:30:45PM +0800, Chen-Yu Tsai wrote:
>> On Thu, Nov 24, 2016 at 5:16 PM, Andre Przywara <andre.przywara at arm.com> wrote:
>>> Hi,
>>>
>>> On 24/11/16 04:16, Chen-Yu Tsai wrote:
>>>> Hi,
>>>>
>>>> On Thu, Nov 24, 2016 at 9:17 AM, Andre Przywara <andre.przywara at arm.com> wrote:
>>>>> The sun6i DMA driver is used in the Allwinner A64 and H5 SoC, which
>>>>> have arm64 capable cores. Add the generic sunxi config symbol to allow
>>>>> the driver to be selected by arm64 Kconfigs, which don't feature
>>>>> SoC specific MACH_xxxx configs.
>>>>>
>>>>> Signed-off-by: Andre Przywara <andre.przywara at arm.com>
>>>>> ---
>>>>>  drivers/dma/Kconfig | 2 +-
>>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
>>>>> index af63a6b..003c284 100644
>>>>> --- a/drivers/dma/Kconfig
>>>>> +++ b/drivers/dma/Kconfig
>>>>> @@ -157,7 +157,7 @@ config DMA_SUN4I
>>>>>
>>>>>  config DMA_SUN6I
>>>>>         tristate "Allwinner A31 SoCs DMA support"
>>>>> -       depends on MACH_SUN6I || MACH_SUN8I || COMPILE_TEST
>>>>> +       depends on MACH_SUN6I || MACH_SUN8I || COMPILE_TEST || ARCH_SUNXI
>>>>
>>>> AFAIK ARCH_SUNXI encompasses/supersedes MACH_SUN*I.
>>>> (And I don't have to add MACH_SUN9I later :) )
>>>
>>> Sure, admittedly it was just a quick hack to get things going.
>>> Actually I don't know why we had a *depend* on those MACH_s before. I
>>> think technically it does not depend on a certain SoC (having the
>>> COMPILE_TEST in there hints on that). So what about:
>>
>> It was really because this DMA engine only comes with the later
>> SoCs. We have dma-sun4i for the older one.
> 
> Indeed.
> 
>> But yes, there's no reason why you can't build it for the earlier
>> SoC. It just doesn't get used.
> 
> I'm still in favor of keeping the depends on. There's no point of
> compiling something we know have zero chance of running.
> 
> (But that would be (ARCH_SUNXI && ARM64))

I am OK with that, just wondering if there is a definition of what
"depends" really means. My impression what that it's a about code
dependencies (requires a certain subsystem, for instance), not really if
it's useful in a particular configuration.

Cheers,
Andre.