Re: [PATCH v5 13/18] pci: introduce pci_find_the_only_child()

[Vladimir Sementsov-Ogievskiy]

On 02.03.23 11:53, Michael S. Tsirkin wrote:
> On Thu, Mar 02, 2023 at 11:45:00AM +0300, Vladimir Sementsov-Ogievskiy wrote:
> > On 02.03.23 11:37, Michael S. Tsirkin wrote:
> > > On Thu, Mar 02, 2023 at 11:28:44AM +0300, Vladimir Sementsov-Ogievskiy wrote:
> > > > On 02.03.23 00:09, Michael S. Tsirkin wrote:
> > > > > On Thu, Feb 16, 2023 at 09:03:51PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> > > > > > To be used in further patch to identify the device hot-plugged into
> > > > > > pcie-root-port.
> > > > > >
> > > > > > Signed-off-by: Vladimir Sementsov-Ogievskiy<vsementsov@yandex-team.ru>
> > > > > > Reviewed-by: Anton Kuchin<antonkuchin@yandex-team.ru>
> > > > > Wait a second does this work for multifunction devices correctly?
> > > >
> > > > I thought about that and I'm just lost:)
> > > >
> > > > Could several (multifunction?) devices be plugged into one pcie-root-port 
> > > > device?
> > >
> > > One device per port but one multifunction device is represented as multiple 
> > > PCIDevice structures.
> >
> > So, it should be OK to send _one_ event for that multifunction device, and the code is 
> > shpc_reset() is OK, but reporting "Several child devices found" is bad idea?
>
> I don't know about your new event, we are discussing it separately.
> yes all functions are removed together normally on real hardware.
>
> > So, if I change the logic from pci_find_the_only_child() to 
> > pci_find_first_child() is it OK?
>
> Yes though I don't like this name either - need to make it clear that
> multifunction is ok, multiple unrelated devices aren't.

Could we check it somehow that all plugged devices represent the one 
multifunction device?

> > > > Same question for SHPC slots. For example, shpc_free_devices_in_slot() looks 
> > > > like we can have several devices in one slot..
> > > > On the other hand, in shpc_reset() we have construction 
> > > > shpc->sec_bus->devices[PCI_DEVFN(SHPC_IDX_TO_PCI(i), 0)] to access the device 
> > > > in slot. The only one device.
> > > >
> > > > --
> > > > Best regards,
> > > > Vladimir
> > >
> > > Same thing.
> > >
> > > ... and let's not get started about sriov and ari ...
> >
> > --
> > Best regards,
> > Vladimir

--
Best regards,
Vladimir