linux-kernel - Re: [PATCH v2 4/8] PCI: brcmstb: Fix error path upon call of regulator_bulk

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Message-ID: <CA+-6iNzvqnZB=7kRqUm5ie6245AM5ObeVmMNQ_S4AtMLD0jKQw@mail.gmail.com>
Date: Tue, 4 Mar 2025 12:24:56 -0500
From: Jim Quinlan <james.quinlan@...adcom.com>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc: linux-pci@...r.kernel.org, Nicolas Saenz Julienne <nsaenz@...nel.org>, 
	Bjorn Helgaas <bhelgaas@...gle.com>, Lorenzo Pieralisi <lorenzo.pieralisi@....com>, 
	Cyril Brulebois <kibi@...ian.org>, Stanimir Varbanov <svarbanov@...e.de>, 
	bcm-kernel-feedback-list@...adcom.com, jim2101024@...il.com, 
	Florian Fainelli <florian.fainelli@...adcom.com>, Lorenzo Pieralisi <lpieralisi@...nel.org>, 
	Krzysztof Wilczyński <kw@...ux.com>, 
	Rob Herring <robh@...nel.org>, 
	"moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" <linux-rpi-kernel@...ts.infradead.org>, 
	"moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" <linux-arm-kernel@...ts.infradead.org>, 
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 4/8] PCI: brcmstb: Fix error path upon call of regulator_bulk_get()

On Tue, Mar 4, 2025 at 12:07 PM Manivannan Sadhasivam
<manivannan.sadhasivam@...aro.org> wrote:
>
> On Tue, Mar 04, 2025 at 11:55:05AM -0500, Jim Quinlan wrote:
> > On Tue, Mar 4, 2025 at 10:03 AM Manivannan Sadhasivam
> > <manivannan.sadhasivam@...aro.org> wrote:
> > >
> > > On Fri, Feb 14, 2025 at 12:39:32PM -0500, Jim Quinlan wrote:
> > > > If regulator_bulk_get() returns an error, no regulators are created and we
> > > > need to set their number to zero.  If we do not do this and the PCIe
> > > > link-up fails, regulator_bulk_free() will be invoked and effect a panic.
> > > >
> > > > Also print out the error value, as we cannot return an error upwards as
> > > > Linux will WARN on an error from add_bus().
> > > >
> > > > Fixes: 9e6be018b263 ("PCI: brcmstb: Enable child bus device regulators from DT")
> > > > Signed-off-by: Jim Quinlan <james.quinlan@...adcom.com>
> > > > ---
> > > >  drivers/pci/controller/pcie-brcmstb.c | 3 ++-
> > > >  1 file changed, 2 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
> > > > index e0b20f58c604..56b49d3cae19 100644
> > > > --- a/drivers/pci/controller/pcie-brcmstb.c
> > > > +++ b/drivers/pci/controller/pcie-brcmstb.c
> > > > @@ -1416,7 +1416,8 @@ static int brcm_pcie_add_bus(struct pci_bus *bus)
> > > >
> > > >               ret = regulator_bulk_get(dev, sr->num_supplies, sr->supplies);
> > > >               if (ret) {
> > > > -                     dev_info(dev, "No regulators for downstream device\n");
> > > > +                     dev_info(dev, "Did not get regulators; err=%d\n", ret);
> > >
> > > Why is this dev_info() instead of dev_err()?
> >
> > I will change this.
> > >
> > > > +                     pcie->sr = NULL;
> > >
> > > Why can't you set 'pcie->sr' after successfull regulator_bulk_get()?
> >
> > Not sure I understand -- it is already set before a  successful
> > regulator_bulk_get() call.
>
> Didn't I say 'after'?

Sorry, I misinterpreted your question.  I can change it but it would
just be churn because a new commit is going to refactor this function.
However,
I can set  pcie->num_regulators "after" in the new commit.

Regards,
Jim Quinlan
Broadcom STB/CM

>
> > I set it to NULL after an unsuccessful result so the structure will
> > not be passed to subsequent calls.
> >
>
> If you set the pointer after a successful regulator_bulk_get(), you do not need
> to set it to NULL for a failure.
>
> - Mani
>
> --
> மணிவண்ணன் சதாசிவம்

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