[RFC 8/9] PCI/pwrseq: add a pwrseq driver for QCA6390

[Chen-Yu Tsai]

On Tue, Jan 9, 2024 at 6:15 PM Arnd Bergmann <arnd at arndb.de> wrote:
>
> On Tue, Jan 9, 2024, at 11:09, Kalle Valo wrote:
> > Chen-Yu Tsai <wenst at chromium.org> writes:
> >> On Tue, Jan 9, 2024 at 5:18 PM Kalle Valo <kvalo at kernel.org> wrote:
> >>> Jeff Johnson <quic_jjohnson at quicinc.com> writes:
> >>>
> >>> > On 1/4/2024 5:01 AM, Bartosz Golaszewski wrote:
> >>> >> diff --git a/drivers/pci/pcie/pwrseq/Kconfig b/drivers/pci/pcie/pwrseq/Kconfig
> >>> >> index 010e31f432c9..f9fe555b8506 100644
> >>> >> --- a/drivers/pci/pcie/pwrseq/Kconfig
> >>> >> +++ b/drivers/pci/pcie/pwrseq/Kconfig
> >>> >> @@ -6,3 +6,14 @@ menuconfig PCIE_PWRSEQ
> >>> >>      help
> >>> >>        Say yes here to enable support for PCIe power sequencing
> >>> >>        drivers.
> >>> >> +
> >>> >> +if PCIE_PWRSEQ
> >>> >> +
> >>> >> +config PCIE_PWRSEQ_QCA6390
> >>> >> +    tristate "PCIe Power Sequencing driver for QCA6390"
> >>> >> +    depends on ARCH_QCOM || COMPILE_TEST
> >>> >> +    help
> >>> >> +      Enable support for the PCIe power sequencing driver for the
> >>> >> +      ath11k module of the QCA6390 WLAN/BT chip.
> >>> >> +
> >>> >> +endif
> >>> >
> >>> > As I mentioned in the 5/9 patch I'm concerned that the current
> >>> > definition of PCIE_PWRSEQ and PCIE_PWRSEQ_QCA6390 will effectively hide
> >>> > the fact that QCA6390 may need additional configuration since the menu
> >>> > item will only show up if you have already enabled PCIE_PWRSEQ.
> >>> > Yes I see that these are set in the defconfig in 9/9 but I'm concerned
> >>> > about the more generic case.
> >>> >
> >>> > I'm wondering if there should be a separate config QCA6390 within ath11k
> >>> > which would then select PCIE_PWRSEQ and PCIE_PWRSEQ_QCA6390
> >>>
> >>> Or is it possible to provide an optional dependency in Kconfig (I guess
> >>
> >> imply PCIE_PWRSEQ
> >> imply PCIE_PWRSEQ_QCA6390
> >> ?
> >
> > Nice, I had forgotten imply altogether. Would 'imply
> > PCIE_PWRSEQ_QCA6390' in ath11k Kconfig be enough to address Jeff's
> > concern?
>
> Please don't use imply (ever), it doesn't normally do
> what you want. In this case, the only effect the
> 'imply' has is to change the default of the PCIE_PWRSEQ_QCA6390
> option when a defconfig contains QCA6390.
>
> If this is indeed what you want, it's still better to do the
> equivalent expression in PCIE_PWRSEQ_QCA6390 rather than ATH11K:
>
> config PCIE_PWRSEQ_QCA6390
>       tristate "PCIe Power Sequencing driver for QCA6390"
>       default ATH11K && ARCH_QCOM

PCIE_PWRSEQ_QCA6390 is also guarded by PCIE_PWRSEQ though. That would
require the default statement to be duplicated to the PCIE_PWRSEQ option
as well.

Presumably we'd get a few more power sequencing drivers, and the list of
default statements for PCIE_PWRSEQ would grow.

If that's acceptable then Arnd's proposal plus duplicating it to
PCIE_PWRSEQ should work as described.

ChenYu