linux-kernel - Re: [PATCH 2/2] PCI: qcom: Move qcom_pcie_icc_opp

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Message-ID: <jdnjyvw2kkos44unooy5ooix3yn2644r4yvtmekoyk2uozjvo5@atigu3wjikss>
Date: Tue, 15 Jul 2025 16:06:59 +0530
From: Manivannan Sadhasivam <mani@...nel.org>
To: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>, 
	Lorenzo Pieralisi <lpieralisi@...nel.org>, Krzysztof Wilczyński <kwilczynski@...nel.org>, 
	Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>, 
	linux-arm-msm@...r.kernel.org, linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Johan Hovold <johan@...nel.org>, Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
Subject: Re: [PATCH 2/2] PCI: qcom: Move qcom_pcie_icc_opp_update() to
 notifier callback

On Tue, Jul 15, 2025 at 11:54:48AM GMT, Konrad Dybcio wrote:
> On 7/14/25 8:01 PM, Manivannan Sadhasivam wrote:
> > It allows us to group all the settings that need to be done when a PCI
> > device is attached to the bus in a single place.
> > 
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>
> > ---
> >  drivers/pci/controller/dwc/pcie-qcom.c | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> > 
> > diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> > index b4993642ed90915299e825e47d282b8175a78346..b364977d78a2c659f65f0f12ce4274601d20eaa6 100644
> > --- a/drivers/pci/controller/dwc/pcie-qcom.c
> > +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> > @@ -1616,8 +1616,6 @@ static irqreturn_t qcom_pcie_global_irq_thread(int irq, void *data)
> >  		pci_lock_rescan_remove();
> >  		pci_rescan_bus(pp->bridge->bus);
> >  		pci_unlock_rescan_remove();
> > -
> > -		qcom_pcie_icc_opp_update(pcie);
> >  	} else {
> >  		dev_WARN_ONCE(dev, 1, "Received unknown event. INT_STATUS: 0x%08x\n",
> >  			      status);
> > @@ -1765,6 +1763,7 @@ static int pcie_qcom_notify(struct notifier_block *nb, unsigned long action,
> >  	switch (action) {
> >  	case BUS_NOTIFY_BIND_DRIVER:
> >  		qcom_pcie_enable_aspm(pdev);
> > +		qcom_pcie_icc_opp_update(pcie);
> 
> So I assume that we're not exactly going to do much with the device if
> there isn't a driver for it, but I have concerns that since the link
> would already be established(?), the icc vote may be too low, especially
> if the user uses something funky like UIO
> 

Hmm, that's a good point. Not enabling ASPM wouldn't have much consequence, but
not updating OPP would be.

Let me think of other ways to call these two APIs during the device addition. If
there are no sane ways, I'll drop *this* patch.

- Mani

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