On Fri, 2018-09-21 at 17:07 +0100, Lorenzo Pieralisi wrote:

On Mon, Sep 10, 2018 at 05:50:20PM +0800, honghui.zhang@mediatek.com wrote:

quoted

From: Honghui Zhang <redacted>

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 <redacted>
Acked-by: Ryder Lee <ryder.lee@mediatek.com>
---
 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