On Wed, 2018-06-27 at 19:35 +0300, Andy Shevchenko wrote:
> On Wed, Jun 27, 2018 at 12:21 PM, <honghui.zhang@xxxxxxxxxxxx> wrote:
> > From: Honghui Zhang <honghui.zhang@xxxxxxxxxxxx>
> >
> > Mediatek's host controller have two slots, each have it's own control
> > registers. The host driver need to identify which slot was connected
> > in order to access the device's configuration space. There's problem
> > for current host driver to find out which slot was connected to for
> > a given EP device.
> >
> > Assuming each slot have connect with one EP device as below:
> >
> > host bridge
> > bus 0 --> __________|_______
> > | |
> > | |
> > slot 0 slot 1
> > bus 1 -->| bus 2 --> |
> > | |
> > EP 0 EP 1
> >
> > While PCI emulation, system software will scan all the PCI device
> > starting from devfn 0. So it will get the proper port for slot0 and
> > slot1 device when using PCI_SLOT(devfn) for match. But it will get
> > the wrong slot for EP1: The devfn will be start from 0 when scanning
> > EP1 behind slot1, it will get port0 since the PCI_SLOT(EP1) is match
> > for port0's slot value. So the host driver should not using EP's devfn
> > but the slot's devfn(the slot which EP was connected to) for match.
> >
> > This patch fix the mtk_pcie_find_port's logical by using the slot's
> > devfn for match.
>
>
> > + list_for_each_entry(port, &pcie->ports, list) {
> > + if (bus->number == 0 && port->slot == PCI_SLOT(devfn)) {
> > return port;
> > + } else if (bus->number != 0) {
>
> You can do it like (no need 'else')
>
> if (...)
> return ...;
> if (bus->number) {
> ...
> }
>
> > + pbus = bus;
> > + do {
> > + dev = pbus->self;
> > + if (port->slot == PCI_SLOT(dev->devfn))
> > + return port;
> > +
> > + pbus = dev->bus;
> > + } while (dev->bus->number != 0);
>
> This can be rewritten like
>
> pbus = bus;
> while (pbus->number) {
> dev = ...;
> ...
> pbus = dev->bus;
> }
>
> and no need for if (bus->number) anymore.
>
Hi, Andy, thanks very much for your advise, I will change it in the next
version.
thanks.
> > + }
> > + }
> >
> > return NULL;
> > }
> > --
> > 2.6.4
> >
>
>
>
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
