On Wed, Mar 01, 2023 at 03:42:44PM +0100, Igor Mammedov wrote:
> On Mon, 13 Feb 2023 11:56:06 +0100
> Philippe Mathieu-Daudé <[email protected]> wrote:
>
> > Experiment after discussing with Thomas around qdev_get_parent_bus:
> > https://lore.kernel.org/qemu-devel/[email protected]/
> >
> > When a QDev plug on a QBus, we'll always use qdev_get_parent_bus()
> > at least once with this type. Why not provide a consistent defined
> > macro instead of:
> > 1/ adding an inlined helper such usb_bus_from_device()
> > or scsi_bus_from_device() with different type checks,
> > 2/ open-code calls to qdev_get_parent_bus() with unsafe casts
> > ?
> >
> > This RFC series introduce a QDev-equivalent of QOM DECLARE_TYPES
> > macro, to be used with a (device, bus) tuple, and declaring the
> > equivalent device_GET_BUS() macro.
> it's already bad having 2 ways to declare types (though SIMPLE was a huge LOC
> saving)
> so question is where do we stop (API explosion ain't a good thing either).
>
> I my opinion this is just code churn for nor tangible benefit,
> given how qdev_get_parent_bus() is used.
Right so in the USB conversion the only improvement is the elimination of
this method:
-static inline USBBus *usb_bus_from_device(USBDevice *d)
-{
- return DO_UPCAST(USBBus, qbus, qdev_get_parent_bus(DEVICE(d)));
-}
It strikes me that we don't have especially many (bus-type, device-type)
pairs that would benefit from this macro.
With regards,
Daniel
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