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Date: Mon, 1 Oct 2018 15:36:41 +0100 From: Lorenzo Pieralisi <lorenzo.pieralisi@....com> To: honghui.zhang@...iatek.com Cc: bhelgaas@...gle.com, linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org, linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org, ryder.lee@...iatek.com, ulf.hansson@...aro.org, marc.zyngier@....com, matthias.bgg@...il.com, devicetree@...r.kernel.org, yingjoe.chen@...iatek.com, eddie.huang@...iatek.com, youlin.pei@...iatek.com, yt.shen@...iatek.com, sean.wang@...iatek.com Subject: Re: [PATCH v5 1/9] PCI: mediatek: Using slot's devfn for compare to fix mtk_pcie_find_port logic On Fri, Sep 28, 2018 at 06:04:32PM +0800, honghui.zhang@...iatek.com wrote: > From: Honghui Zhang <honghui.zhang@...iatek.com> > > 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@...iatek.com> > --- > 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 >
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