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

From: "Arnd Bergmann" <arnd@arndb.de>
To: "Kalle Valo" <kvalo@kernel.org>, "Chen-Yu Tsai" <wenst@chromium.org>
Cc: "Jeff Johnson" <quic_jjohnson@quicinc.com>,
	"Bartosz Golaszewski" <brgl@bgdev.pl>,
	"David S . Miller" <davem@davemloft.net>,
	"Eric Dumazet" <edumazet@google.com>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Paolo Abeni" <pabeni@redhat.com>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>,
	"Conor Dooley" <conor+dt@kernel.org>,
	"Bjorn Andersson" <andersson@kernel.org>,
	"Konrad Dybcio" <konrad.dybcio@linaro.org>,
	"Catalin Marinas" <catalin.marinas@arm.com>,
	"Will Deacon" <will@kernel.org>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"Heiko Stübner" <heiko@sntech.de>,
	"Jernej Skrabec" <jernej.skrabec@gmail.com>,
	"Chris Morgan" <macromorgan@hotmail.com>,
	"Linus Walleij" <linus.walleij@linaro.org>,
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	"Kuppuswamy Sathyanarayanan"
	<sathyanarayanan.kuppuswamy@linux.intel.com>,
	"Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>,
	"Huacai Chen" <chenhuacai@kernel.org>,
	"Alex Elder" <elder@linaro.org>,
	"Srinivas Kandagatla" <srinivas.kandagatla@linaro.org>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	linux-wireless@vger.kernel.org, Netdev <netdev@vger.kernel.org>,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-msm@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org,
	"Bartosz Golaszewski" <bartosz.golaszewski@linaro.org>
Subject: Re: [RFC 8/9] PCI/pwrseq: add a pwrseq driver for QCA6390
Date: Tue, 09 Jan 2024 11:14:43 +0100	[thread overview]
Message-ID: <5904461c-ca3c-4eb1-a44a-876872234545@app.fastmail.com> (raw)
In-Reply-To: <87bk9uzum9.fsf@kernel.org>

On Tue, Jan 9, 2024, at 11:09, Kalle Valo wrote:
> Chen-Yu Tsai <wenst@chromium.org> writes:
>> On Tue, Jan 9, 2024 at 5:18 PM Kalle Valo <kvalo@kernel.org> wrote:
>>> Jeff Johnson <quic_jjohnson@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

      Arnd