On Wed, Jun 27, 2018 at 05:21:35PM +0800, 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.
The Mediatek host controller has two slots, each with its own control
registers.
> 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
s/While PCI emulation/During PCI enumeration/
> 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>
> Reviewed-by: Ryder Lee <ryder.lee@xxxxxxxxxxxx>
> ---
> drivers/pci/controller/pcie-mediatek.c | 17 +++++++++++++++--
> 1 file changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/controller/pcie-mediatek.c b/drivers/pci/controller/pcie-mediatek.c
> index 0baabe3..9cf7ecf 100644
> --- a/drivers/pci/controller/pcie-mediatek.c
> +++ b/drivers/pci/controller/pcie-mediatek.c
> @@ -337,10 +337,23 @@ 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) {
mvebu has the identical hardware structure but uses an array instead
of a list:
num = of_get_available_child_count(np);
pcie->ports = devm_kcalloc(dev, num, sizeof(*pcie->ports), GFP_KERNEL);
for_each_available_child_of_node(np, child) {
struct mvebu_pcie_port *port = &pcie->ports[i];
mvebu_pcie_parse_port(pcie, port, child);
}
It would be nice if mvebu and mtk used the same strategy so the code
looks the same.
> + if (bus->number == 0 && port->slot == PCI_SLOT(devfn)) {
Is the root bus number fixed at 0 or is it programmable? Many drivers
do something like this:
if (bus->number == pcie->root_bus_nr)
to handle the case of the root bus number being programmable.
> return port;
> + } else if (bus->number != 0) {
> + pbus = bus;
> + do {
> + dev = pbus->self;
> + if (port->slot == PCI_SLOT(dev->devfn))
> + return port;
> +
> + pbus = dev->bus;
> + } while (dev->bus->number != 0);
You should not need to search up the tree of dev->bus->self.
mvebu_pcie_find_port() checks the root port secondary and subordinate
bus numbers, which should work here, too.
> + }
> + }
>
> return NULL;
> }
> --
> 2.6.4
>
>
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