linux-kernel - Re: [PATCH v4 1/5] arm64: Kconfig: enable PCI Power Control Slot driver for QCOM

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Message-ID: <aEEqIWSU5P9Xp9J/@hu-qianyu-lv.qualcomm.com>
Date: Wed, 4 Jun 2025 22:24:49 -0700
From: Qiang Yu <qiang.yu@....qualcomm.com>
To: Bjorn Andersson <andersson@...nel.org>
Cc: Wenbin Yao <quic_wenbyao@...cinc.com>, catalin.marinas@....com,
        will@...nel.org, linux-arm-kernel@...ts.infradead.org,
        konradybcio@...nel.org, robh@...nel.org, krzk+dt@...nel.org,
        conor+dt@...nel.org, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        vkoul@...nel.org, kishon@...nel.org, sfr@...b.auug.org.au,
        linux-phy@...ts.infradead.org, krishna.chundru@....qualcomm.com,
        quic_vbadigan@...cinc.com, quic_mrana@...cinc.com,
        quic_cang@...cinc.com
Subject: Re: [PATCH v4 1/5] arm64: Kconfig: enable PCI Power Control Slot
 driver for QCOM

On Wed, Jun 04, 2025 at 03:30:22PM -0500, Bjorn Andersson wrote:
> On Wed, Jun 04, 2025 at 04:02:33PM +0800, Wenbin Yao wrote:
> > From: Qiang Yu <qiang.yu@....qualcomm.com>
> > 
> > Enable the pwrctrl driver, which is utilized to manage the power supplies
> > of the devices connected to the PCI slots. This ensures that the voltage
> > rails of the standard PCI slots on some platforms eg. X1E80100-QCP can be
> > correctly turned on/off if they are described under PCIe port device tree
> > node.
> > 
> > Signed-off-by: Qiang Yu <qiang.yu@....qualcomm.com>
> > Signed-off-by: Wenbin Yao <quic_wenbyao@...cinc.com>
> > ---
> >  arch/arm64/Kconfig.platforms | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/arch/arm64/Kconfig.platforms b/arch/arm64/Kconfig.platforms
> > index a541bb029..0ffd65e36 100644
> > --- a/arch/arm64/Kconfig.platforms
> > +++ b/arch/arm64/Kconfig.platforms
> > @@ -270,6 +270,7 @@ config ARCH_QCOM
> >  	select GPIOLIB
> >  	select PINCTRL
> >  	select HAVE_PWRCTRL if PCI
> > +	select PCI_PWRCTRL_SLOT if PCI
> 
> PWRCTL isn't a fundamental feature of ARCH_QCOM, so why do we select it
> here?
> 
We were asked to select it in the same way as PCI_PWRCTL_PWRSEQ, following
an approach like:

select PCI_PWRCTL_SLOT if ARCH_QCOM in Kconfig and nothing in defconfig.

But to be honest, we didn't figure out a more appropriate way. Unlike
PCI_PWRCTL_PWRSEQ, which is selected by ath11k/ath12k, PCI_PWRCTL_SLOT
doesn't have a specific endpoint device driver to select it. Would it be
appropriate to add "select PCI_PWRCTL_SLOT if HAVE_PWRCTL" in the Kconfig
for portdrv? Do you have any recommendations?

> Regards,
> Bjorn
> 
> >  	help
> >  	  This enables support for the ARMv8 based Qualcomm chipsets.
> >  
> > -- 
> > 2.34.1
> >