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References: <20230420125941.333675-1-kai.heng.feng@canonical.com> <e84eda25-dbe9-a108-c4d4-ee3fa746d9ca@linux.intel.com>
In-Reply-To: <e84eda25-dbe9-a108-c4d4-ee3fa746d9ca@linux.intel.com>
From:   Kai-Heng Feng <kai.heng.feng@canonical.com>
Date:   Fri, 21 Apr 2023 09:35:57 +0800
Message-ID: <CAAd53p4hYR9f_Mh9cxGfBVnK_akLQMBACLDBnEHHzacJ5OZEGg@mail.gmail.com>
Subject: Re: [PATCH v3 1/4] PCI: Keep AER status in pci_restore_state()
To:     Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@linux.intel.com>
Cc:     bhelgaas@google.com, mika.westerberg@linux.intel.com,
        koba.ko@canonical.com, linux-pci@vger.kernel.org,
        linux-kernel@vger.kernel.org
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Hi Sathyanarayanan,

On Thu, Apr 20, 2023 at 10:39=E2=80=AFPM Sathyanarayanan Kuppuswamy
<sathyanarayanan.kuppuswamy@linux.intel.com> wrote:
>
> Hi Kai,

It's Kai-Heng :)

>
> On 4/20/23 5:59 AM, Kai-Heng Feng wrote:
> > When AER is using the same IRQ as PME, AER interrupt is treated as a
> > wakeup event and it can disrupt system suspend process.
> >
> > If that happens, the system will report it's woken up by PME IRQ withou=
t
> > indicating any AER error since AER status is cleared on resume.
> >
> > So keep the AER status so users can know the system is woken up by AER
> > instead of PME.
> >
> > Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> > Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> > ---
>
> Any history on why it is cleared before? Is it done to hide some resume
> issues?

It was introduced by commit b07461a8e45b ("PCI/AER: Clear error status
registers during enumeration and restore").
The justification is quite reasonable so I think maybe we should keep it as=
 is.

Kai-Heng

>
> > v3:
> >  - No change.
> >
> > v2:
> >  - New patch.
> >
> >  drivers/pci/pci.c | 1 -
> >  1 file changed, 1 deletion(-)
> >
> > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > index 7a67611dc5f4..71aead00fc20 100644
> > --- a/drivers/pci/pci.c
> > +++ b/drivers/pci/pci.c
> > @@ -1778,7 +1778,6 @@ void pci_restore_state(struct pci_dev *dev)
> >       pci_restore_dpc_state(dev);
> >       pci_restore_ptm_state(dev);
> >
> > -     pci_aer_clear_status(dev);
> >       pci_restore_aer_state(dev);
> >
> >       pci_restore_config_space(dev);
>
> --
> Sathyanarayanan Kuppuswamy
> Linux Kernel Developer