Re: [PATCH 2/5] gpio/xilinx: enable for MIPS

[Moritz Fischer <moritz.fischer@xxxxxxxxx>]

On Wed, Oct 14, 2015 at 10:33 AM, Sören Brinkmann
<soren.brinkmann@xxxxxxxxxx> wrote:
> On Wed, 2015-10-14 at 07:24PM +0200, Lars-Peter Clausen wrote:
>> On 10/14/2015 06:54 PM, Sören Brinkmann wrote:
>> > On Wed, 2015-10-14 at 05:57PM +0200, Lars-Peter Clausen wrote:
>> >> On 10/14/2015 05:18 PM, Sören Brinkmann wrote:
>> >>> On Wed, 2015-10-14 at 01:51PM +0100, Zubair Lutfullah Kakakhel wrote:
>> >>>> MIPSfpga uses the axi gpio controller. Enable the driver for MIPS.
>> >>>>
>> >>>> Signed-off-by: Zubair Lutfullah Kakakhel <Zubair.Kakakhel@xxxxxxxxxx>
>> >>>> ---
>> >>>>  drivers/gpio/Kconfig | 2 +-
>> >>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> >>>>
>> >>>> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
>> >>>> index 8949b3f..58e9afd 100644
>> >>>> --- a/drivers/gpio/Kconfig
>> >>>> +++ b/drivers/gpio/Kconfig
>> >>>> @@ -508,7 +508,7 @@ config GPIO_XGENE_SB
>> >>>>
>> >>>>  config GPIO_XILINX
>> >>>>          tristate "Xilinx GPIO support"
>> >>>> -        depends on OF_GPIO && (PPC || MICROBLAZE || ARCH_ZYNQ || X86)
>> >>>> +        depends on OF_GPIO && (PPC || MICROBLAZE || ARCH_ZYNQ || X86 || MIPS)
>> >>>
>> >>> Hmm, in general, this driver is hopefully generic enough that it doesn't
>> >>> have any real architecture dependencies. And I suspect, we want to
>> >>> enable this driver for ARM64 for ZynqMP soon too. Should we probably
>> >>> drop these arch dependencies completely? It seems to become quite a long list.
>> >>
>> >> I've been thinking about this a while ago. This is certainly not the only
>> >> driver affected by this problem. But the thing is people always complain if
>> >> new symbols become visable in Kconfig that don't apply to their platform.
>> >>
>> >> Maybe we should introduce a HAS_REPROGRAMABLE_LOGIC (or similar) feature
>> >> Kconfig symbol and let platforms which have a FPGA select it and let drivers
>> >> for FPGA peripherals depend on it.
>> >
>> > Sounds like a good idea to me. But, does that work for all use-cases.
>> > E.g. if you plug some PCIe card with an FPGA into an x86(_64) machine.
>> > That would allow you to use those drivers, but I'm not sure how that
>> > could pull in the new config symbol.
>>
>> Hm, right. We could also make it a user-selectable config symbol. In that
>> case you only need to disable one symbol when you don't have FPGA support
>> rather than one for each driver. Although I'm not quite sure where to put
>> such a symbol.
>
> Eventually, the FPGA manager subsystem could probably provide some high
> level config symbols. Though, it is probably also not given that every
> FPGA-enabled platform needs the FPGA manager.

I agree. I suspect most platforms will not actually runtime reload the
FPGA using
FPGA manager they probably use onboard flash or something similar.

>
>         Sören
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Moritz
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