Hi Bjorn, Thanks a lot for your comments! > -----Original Message----- > From: Bjorn Helgaas [mailto:helgaas@xxxxxxxxxx] > Sent: 2017年10月12日 3:38 > To: Z.q. Hou <zhiqiang.hou@xxxxxxx> > Cc: linux-kernel@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; > linux-pci@xxxxxxxxxxxxxxx; bhelgaas@xxxxxxxxxx; Roy Zang > <roy.zang@xxxxxxx>; Mingkai Hu <mingkai.hu@xxxxxxx>; M.h. Lian > <minghuan.lian@xxxxxxx> > Subject: Re: [PATCH 1/2] PCI: Disable MSI for Freescale PCIe RC mode > > On Fri, Sep 22, 2017 at 03:25:21PM +0800, Zhiqiang Hou wrote: > > From: Hou Zhiqiang <Zhiqiang.Hou@xxxxxxx> > > > > The Freescale PCIe controller advertises the MSI/MSI-X capability in > > both RC and Endpoint mode, but in RC mode it doesn't support MSI/MSI-X > > by it self, it can only transfer MSI/MSI-X from downstream > > s/it self,/itself;/ I'll fix this typo in next version. > > devices. So add this quirk to prevent use of MSI/MSI-X in RC mode. > > > > Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@xxxxxxx> > > --- > > drivers/pci/quirks.c | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c index > > a4d33619a7bb..c1063a420f0c 100644 > > --- a/drivers/pci/quirks.c > > +++ b/drivers/pci/quirks.c > > @@ -4799,3 +4799,11 @@ static void quirk_no_ats(struct pci_dev *pdev) > > /* AMD Stoney platform GPU */ > > DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x98e4, quirk_no_ats); > > #endif /* CONFIG_PCI_ATS */ > > + > > +/* Freescale PCIe doesn't support MSI in RC mode */ static void > > +quirk_fsl_no_msi(struct pci_dev *pdev) { > > + if (pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT) > > + pdev->no_msi = 1; > > +} > > +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_FREESCALE, PCI_ANY_ID, > > +quirk_fsl_no_msi); > > This disables MSI for all Freescale root ports, past, present, and future. Is > that really what you want? This is a bug (the root port shouldn't advertise > MSI if it doesn't support it), and presumably it might be fixed in some future > device? For the past and present, there isn't Freescale root ports supporting MSI. If the future Freescale root port support MSI, I'll add a patch for it checking the PCI device ID to determine if apply the quirk. And it should be ok for the root ports without this bug. > > This needs an ack from Minghuan or Mingkai (based on MAINTAINERS). > Thanks, Zhiqiang
