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

Greg KH gregkh at linuxfoundation.org
Mon Nov 6 14:46:50 UTC 2017


On Mon, Nov 06, 2017 at 03:42:04PM +0100, Benjamin Gaignard wrote:
> 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 ?

I would like to see that...

thanks,

greg k-h


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