[PATCH v6 2/2] staging: ion: create one device entry per heap

Benjamin Gaignard benjamin.gaignard at linaro.org
Mon Nov 6 14:42:04 UTC 2017


2017-11-02 12:10 GMT+01:00 Mark Brown <broonie at kernel.org>:
> On Thu, Nov 02, 2017 at 11:44:07AM +0100, Greg KH wrote:
>> On Tue, Oct 31, 2017 at 07:11:53PM +0000, Mark Brown wrote:
>
>> > There was a discussion a while ago in the context of I2C/SPI MFDs
>> > which concluded that if you need a bus and it's going to be effectively
>> > noop then you should just use the platform bus as anything else will
>> > consist almost entirely of cut'n'paste from the platform bus with some
>> > light sed usage and code duplication is bad.  It's not super lovely as
>> > it's not actually a memory mapped device but it's the best idea we've
>> > got.
>
>> Ugh, I hate that.  What's wrong with using a "virtual" device instead?
>
> It was the duplication, initially everyone was making buses.
>
>> I can create a "virtual" bus for things like this if they really want a
>> "simple" bus, abusing platform for this is the major reason I hate the
>> platform bus code...
>
> In the MFD case they're physical devices, they're just usually on the
> wrong side of an I2C or SPI link.  Plus MFD already handles platform
> devices for things that are memory mapped so it's a bit of a more
> natural fit there.

What I can do is to register an ion bus (like cec one for example),
add one ion parent device so heaps will appear in /sys/bus/ion/ion*
and /sys/devices/ion/ion*

Does that could sound good enough ?

Benjamin


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