Re: [PATCH V7 02/15] PCI: Disable MSI for Tegra194 root port

[Vidya Sagar]

On 5/21/2019 10:17 PM, Vidya Sagar wrote:
> On 5/21/2019 3:57 PM, Thierry Reding wrote:
> > On Fri, May 17, 2019 at 06:08:33PM +0530, Vidya Sagar wrote:
> > > Tegra194 rootports don't generate MSI interrupts for PME events and hence
> > > MSI needs to be disabled for them to avoid root ports service drivers
> > > registering their respective ISRs with MSI interrupt.
> > >
> > > Signed-off-by: Vidya Sagar <vidyas@xxxxxxxxxx>
> > > ---
> > > Changes since [v6]:
> > > * This is a new patch
> > >
> > >   drivers/pci/quirks.c | 14 ++++++++++++++
> > >   1 file changed, 14 insertions(+)
> > >
> > > diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> > > index 0f16acc323c6..28f9a0380df5 100644
> > > --- a/drivers/pci/quirks.c
> > > +++ b/drivers/pci/quirks.c
> > > @@ -2592,6 +2592,20 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_NVIDIA,
> > >               PCI_DEVICE_ID_NVIDIA_NVENET_15,
> > >               nvenet_msi_disable);
> > > +/*
> > > + * Tegra194's PCIe root ports don't generate MSI interrupts for PME events
> > > + * instead legacy interrupts are generated. Hence, to avoid service drivers
> > > + * registering their respective ISRs for MSIs, need to disable MSI interrupts
> > > + * for root ports.
> > > + */
> > > +static void disable_tegra194_rp_msi(struct pci_dev *dev)
> > > +{
> > > +    dev->no_msi = 1;
> > > +}
> > > +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_NVIDIA, 0x1ad0, disable_tegra194_rp_msi);
> > > +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_NVIDIA, 0x1ad1, disable_tegra194_rp_msi);
> > > +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_NVIDIA, 0x1ad2, disable_tegra194_rp_msi);
> > > +
> >
> > Later functions in this file seem to use a more consistent naming
> > pattern, according to which the name for this would become:
> >
> >     pci_quirk_nvidia_tegra194_disable_rp_msi
> >
> > Might be worth considering making this consistent.
> >
> > This could also be moved to the DWC driver to restrict this to where it
> > is needed. In either case, this seems like a good solution, so:
> >
> > Reviewed-by: Thierry Reding <treding@xxxxxxxxxx>
> Ok. I'll move it to DWC driver along with name change for the quirk API.
I see that if quirk macros and API are present in pcie-tegra194.c file and driver is built
as a module, quirk API is not getting invoked by the system, whereas it gets invoked if driver
is built into kernel. Is this behavior expected? I think it is because of quirk API symbol
not available as part of global quirk symbol table when driver is built as a module?
for now, I'm going to keep quirk macros and API in pci/quirks.c file itself.