On Wed, 2018-06-27 at 19:35 +0300, Andy Shevchenko wrote:

On Wed, Jun 27, 2018 at 12:21 PM,  [off-list ref] wrote:

quoted

From: Honghui Zhang <redacted>

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.

quoted

+       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) {
 ...
}

quoted

+                       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.

quoted

+               }
+       }

        return NULL;
 }
--
2.6.4