On Fri, Sep 28, 2018 at 06:04:32PM +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 logic by using the slot's
> devfn for match if finding device connected to the subordinate bus.
>
> Signed-off-by: Honghui Zhang <honghui.zhang@xxxxxxxxxxxx>
> ---
> drivers/pci/controller/pcie-mediatek.c | 17 ++++++++++++++++-
> 1 file changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/controller/pcie-mediatek.c b/drivers/pci/controller/pcie-mediatek.c
> index 9999dae..264e03f 100644
> --- a/drivers/pci/controller/pcie-mediatek.c
> +++ b/drivers/pci/controller/pcie-mediatek.c
> @@ -337,10 +337,25 @@ 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 = NULL;
> +
> + /*
> + * Walk the bus hierarchy to get the devfn value
> + * of the port in the root bus.
> + */
> + while (bus && bus->number) {
> + dev = bus->self;
> + bus = dev->bus;
If you add:
devfn = dev->devfn;
here
> + }
> +
> + list_for_each_entry(port, &pcie->ports, list) {
> + /* Using slot's devfn to compare for subordinary bus. */
> + if (dev)
> + devfn = dev->devfn;
You can remove this ugly hunk altogether (and dev initialization
to NULL).
Lorenzo
> - list_for_each_entry(port, &pcie->ports, list)
> if (port->slot == PCI_SLOT(devfn))
> return port;
> + }
>
> return NULL;
> }
> --
> 2.6.4
>
