Re: [PATCH V5 5/5] PCI: tegra: Add support for PCIe endpoint mode in Tegra194

[Vidya Sagar]

On 3/31/2020 3:17 AM, Bjorn Helgaas wrote:
> External email: Use caution opening links or attachments
>
>
> On Tue, Mar 03, 2020 at 11:40:52PM +0530, Vidya Sagar wrote:
> > Add support for the endpoint mode of Synopsys DesignWare core based
> > dual mode PCIe controllers present in Tegra194 SoC.
> >
> > Signed-off-by: Vidya Sagar <vidyas@xxxxxxxxxx>
> > Acked-by: Thierry Reding <treding@xxxxxxxxxx>
> > ---
> > V5:
> > * Added Acked-by: Thierry Reding <treding@xxxxxxxxxx>
> > * Removed unwanted header file inclusion
> >
> > V4:
> > * Addressed Lorenzo's review comments
> > * Started using threaded irqs instead of kthreads
> >
> > V3:
> > * Addressed Thierry's review comments
> >
> > V2:
> > * Addressed Bjorn's review comments
> > * Made changes as part of addressing review comments for other patches
> >
> >   drivers/pci/controller/dwc/Kconfig         |  30 +-
> >   drivers/pci/controller/dwc/pcie-tegra194.c | 679 ++++++++++++++++++++-
> >   2 files changed, 691 insertions(+), 18 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/Kconfig b/drivers/pci/controller/dwc/Kconfig
> > index 0830dfcfa43a..169cde58dd92 100644
> > --- a/drivers/pci/controller/dwc/Kconfig
> > +++ b/drivers/pci/controller/dwc/Kconfig
> > @@ -248,14 +248,38 @@ config PCI_MESON
> >          implement the driver.
> >
> >   config PCIE_TEGRA194
> > -     tristate "NVIDIA Tegra194 (and later) PCIe controller"
> > +     tristate
> > +
> > +config PCIE_TEGRA194_HOST
> > +     tristate "NVIDIA Tegra194 (and later) PCIe controller - Host Mode"
> >        depends on ARCH_TEGRA_194_SOC || COMPILE_TEST
> >        depends on PCI_MSI_IRQ_DOMAIN
> >        select PCIE_DW_HOST
> >        select PHY_TEGRA194_P2U
> > +     select PCIE_TEGRA194
> > +     default y
>
> Sorry I missed this before, but why is this "default y"?  From
> Documentation/kbuild/kconfig-language.rst:
>
>    The default value deliberately defaults to 'n' in order to avoid
>    bloating the build. With few exceptions, new config options should
>    not change this. The intent is for "make oldconfig" to add as little
>    as possible to the config from release to release.
>
> I do see that several other things in other drivers/pci/ Kconfig files
> are also "default y", and we should probably change some of them.  But
> I don't want to add even more unless there's a good reason.
>
> I'm not looking for more reactions like these:
>
> https://lore.kernel.org/r/CAHk-=wiZ24JuVehJ5sEC0UG1Gk2nvB363wO02RRsR1oEht6R9Q@xxxxxxxxxxxxxx
> https://lore.kernel.org/r/CA+55aFzPpuHU1Nqd595SEQS=F+kXMzPs0Rba9FUgTodGxmXsgg@xxxxxxxxxxxxxx
>
> Can you please update this patch to either remove the "default y" or
> add the rationale for keeping it?
I'm fine with removing 'default y' line.
Should I send a patch only with this change?

Thanks,
Vidya Sagar
> > +     help
> > +       Enables support for the PCIe controller in the NVIDIA Tegra194 SoC to
> > +       work in host mode. There are two instances of PCIe controllers in
> > +       Tegra194. This controller can work either as EP or RC. In order to
> > +       enable host-specific features PCIE_TEGRA194_HOST must be selected and
> > +       in order to enable device-specific features PCIE_TEGRA194_EP must be
> > +       selected. This uses the DesignWare core.