On Fri, 2018-09-21 at 17:07 +0100, Lorenzo Pieralisi wrote:
> On Mon, Sep 10, 2018 at 05:50:20PM +0800, honghui.zhang@xxxxxxxxxxxx wrote:
> > From: Honghui Zhang <honghui.zhang@xxxxxxxxxxxx>
> >
> > The Mediatek's host controller has two slots, each with 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
> >
> > During PCI enumeration, 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.
> >
> > Signed-off-by: Honghui Zhang <honghui.zhang@xxxxxxxxxxxx>
> > Acked-by: Ryder Lee <ryder.lee@xxxxxxxxxxxx>
> > ---
> > drivers/pci/controller/pcie-mediatek.c | 19 +++++++++++++++++--
> > 1 file changed, 17 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/pci/controller/pcie-mediatek.c b/drivers/pci/controller/pcie-mediatek.c
> > index 861dda6..20b9088 100644
> > --- a/drivers/pci/controller/pcie-mediatek.c
> > +++ b/drivers/pci/controller/pcie-mediatek.c
> > @@ -337,11 +337,26 @@ static struct mtk_pcie_port *mtk_pcie_find_port(struct pci_bus *bus,
> > {
> > struct mtk_pcie *pcie = bus->sysdata;
> > struct mtk_pcie_port *port;
> > + struct pci_dev *dev;
> > + struct pci_bus *pbus;
> >
> > - list_for_each_entry(port, &pcie->ports, list)
> > - if (port->slot == PCI_SLOT(devfn))
> > + list_for_each_entry(port, &pcie->ports, list) {
> > + if (!bus->number && port->slot == PCI_SLOT(devfn))
> > return port;
> >
> > + if (bus->number) {
> > + pbus = bus;
> > +
> > + while (pbus->number) {
> > + dev = pbus->self;
> > + pbus = dev->bus;
> > + }
> > +
> > + if (port->slot == PCI_SLOT(dev->devfn))
> > + return port;
> > + }
> > + }
>
> /*
> * Walk the bus hierarchy to get the devfn value
> * of the port in the root bus.
> */
> while (bus && bus->number) {
> devfn = bus->self->devfn;
> bus = bus->parent;
> }
>
> list_for_each_entry(port, &pcie->ports, list) {
> if (port->slot == PCI_SLOT(devfn))
> return port;
>
> return NULL;
>
> Would it work ? Maybe it is a little easier to parse.
>
Thanks, this is much better.
> I think this can even be made easier by using struct device_node* as
> comparison (and store it in port->slot instead of the port number), I
> think that the pci_dev representing the port should have the right
> of_node associated with it by core code, so it is just a matter of
> finding the first pci_dev parent with an of_node set and compare it
> against port->slot (that should be converted to a struct device_node*).
>
> This ought to be tested and written but I think that's doable.
>
Thanks, I will do my homework and figure a way out through this
solution.
Currently port->slot is used in too much place to be removed, I guess I
need to added a new parameter in the port struct to store the of_node
for compare.
I'm not sure which way is better, anyway, let me try the new solution.
thanks.
> Lorenzo
