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References: <20211110221456.11977-2-jim2101024@gmail.com> <20211111215718.GA1353371@bhelgaas>
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From:   Jim Quinlan <james.quinlan@broadcom.com>
Date:   Mon, 15 Nov 2021 15:56:14 -0500
Message-ID: <CA+-6iNy86LG761MYvr-mB0de1TZ_EbJxzw0vFYfgXaa+96k=GA@mail.gmail.com>
Subject: Re: [PATCH v8 1/8] PCI: brcmstb: Change brcm_phy_stop() to return void
To:     Bjorn Helgaas <helgaas@kernel.org>
Cc:     Jim Quinlan <jim2101024@gmail.com>,
        "open list:PCI NATIVE HOST BRIDGE AND ENDPOINT DRIVERS" 
        <linux-pci@vger.kernel.org>, Bjorn Helgaas <bhelgaas@google.com>,
        Nicolas Saenz Julienne <nsaenz@kernel.org>,
        Rob Herring <robh@kernel.org>, Mark Brown <broonie@kernel.org>,
        "maintainer:BROADCOM BCM7XXX ARM ARCHITECTURE" 
        <bcm-kernel-feedback-list@broadcom.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        =?UTF-8?Q?Krzysztof_Wilczy=C5=84ski?= <kw@linux.com>,
        "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" 
        <linux-rpi-kernel@lists.infradead.org>,
        "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" 
        <linux-arm-kernel@lists.infradead.org>,
        open list <linux-kernel@vger.kernel.org>
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On Thu, Nov 11, 2021 at 4:57 PM Bjorn Helgaas <helgaas@kernel.org> wrote:
>
> On Wed, Nov 10, 2021 at 05:14:41PM -0500, Jim Quinlan wrote:
> > We do not use the result of this function so make it void.
>
> I don't get it.  Can you expand on this?
>
> brcm_phy_cntl() can return -EIO, which means brcm_phy_stop() can
> return -EIO, which means brcm_pcie_suspend can return -EIO.
> brcm_pcie_suspend() is the dev_pm_ops.suspend() method.
>
> So are you saying we never use the result of dev_pm_ops.suspend()?
Hi Bjorn,

In this situation we are going into suspend.  In doing so, any
problems with the brcm phy may be erased/forgiven upon resume, since
clocks are turned off and most power removed/reduced.  An error from
brcm_phy_stop() that becomes the return value of  brcm_pcie_suspend()
will bring a halt to the entire suspend IIRC.   In fact, I forced a
-EIO in this code and it panic'd on suspend.  This is not really the
behavior I want for what is most likely a recoverable error.

Perhaps a dev_err(...) will suffice while still returning 0?

I noticed that reset_control_rearm() also returns a value, and if that
is in error it will not be erease/forgiven  by suspend sleep.  I will
fix this.

Regards,
Jim Quinlan
Broadcom STB


>
> > Signed-off-by: Jim Quinlan <jim2101024@gmail.com>
> > ---
> >  drivers/pci/controller/pcie-brcmstb.c | 10 +++++-----
> >  1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
> > index cc30215f5a43..ff7d0d291531 100644
> > --- a/drivers/pci/controller/pcie-brcmstb.c
> > +++ b/drivers/pci/controller/pcie-brcmstb.c
> > @@ -1111,9 +1111,10 @@ static inline int brcm_phy_start(struct brcm_pcie *pcie)
> >       return pcie->rescal ? brcm_phy_cntl(pcie, 1) : 0;
> >  }
> >
> > -static inline int brcm_phy_stop(struct brcm_pcie *pcie)
> > +static inline void brcm_phy_stop(struct brcm_pcie *pcie)
> >  {
> > -     return pcie->rescal ? brcm_phy_cntl(pcie, 0) : 0;
> > +     if (pcie->rescal)
> > +             brcm_phy_cntl(pcie, 0);
> >  }
> >
> >  static void brcm_pcie_turn_off(struct brcm_pcie *pcie)
> > @@ -1143,14 +1144,13 @@ static void brcm_pcie_turn_off(struct brcm_pcie *pcie)
> >  static int brcm_pcie_suspend(struct device *dev)
> >  {
> >       struct brcm_pcie *pcie = dev_get_drvdata(dev);
> > -     int ret;
> >
> >       brcm_pcie_turn_off(pcie);
> > -     ret = brcm_phy_stop(pcie);
> > +     brcm_phy_stop(pcie);
> >       reset_control_rearm(pcie->rescal);
> >       clk_disable_unprepare(pcie->clk);
> >
> > -     return ret;
> > +     return 0;
> >  }
> >
> >  static int brcm_pcie_resume(struct device *dev)
> > --
> > 2.17.1
> >