Re: [PATCH v5 1/1] serial: core: Start managing serial controllers to enable runtime PM

[Greg Kroah-Hartman]

On Wed, Feb 01, 2023 at 08:38:42AM +0200, Tony Lindgren wrote:
> * Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> [230131 10:10]:
> > On Mon, Jan 16, 2023 at 09:59:58AM +0200, Tony Lindgren wrote:
> > > We want to enable runtime PM for serial port device drivers in a generic
> > > way. To do this, we want to have the serial core layer manage the
> > > registered physical serial controller devices.
> > > 
> > > To do this, let's set up a struct device for the serial core controller
> > > as suggested by Greg and Jiri. The serial core controller devices are
> > > children of the physical serial port device. The serial core controller
> > > device is needed to support multiple different kind of ports connected
> > > to single physical serial port device.
> > > 
> > > Let's also set up a struct device for the serial core port. The serial
> > > core port instances are children of the serial core controller device.
> > 
> > Looking better, but why is this new device a platform device?  That
> > feels odd, you should never have a platform device hanging off of a
> > non-platform device, right?
> 
> No special need for it to be a platform device. It just is easy to set
> up, and for my test case the serial port physical device is also a
> platform device.
> 
> What's your preference here?

Never make up a "fake" platform device please.  Only use them for real
platform devices.  Use a virtual device if you want a virtual one.

thanks,

greg k-h