linux-kernel - Re: [PATCH 3/3] PCI/AER: Use pci_aer_raw_clear_status() to clear root port's AER error status

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Date:   Mon, 26 Sep 2022 12:22:46 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Zhuo Chen <chenzhuo.1@...edance.com>
Cc:     allenbh@...il.com, dave.jiang@...el.com,
        linux-scsi@...r.kernel.org, martin.petersen@...cle.com,
        linux-pci@...r.kernel.org, jejb@...ux.ibm.com, jdmason@...zu.us,
        james.smart@...adcom.com, fancer.lancer@...il.com,
        linux-kernel@...r.kernel.org, ntb@...ts.linux.dev,
        oohall@...il.com, bhelgaas@...gle.com, dick.kennedy@...adcom.com,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH 3/3] PCI/AER: Use pci_aer_raw_clear_status() to clear
 root port's AER error status

On Mon, Sep 26, 2022 at 10:16:23PM +0800, Zhuo Chen wrote:
> On 9/23/22 5:50 AM, Bjorn Helgaas wrote:
> > On Fri, Sep 02, 2022 at 02:16:34AM +0800, Zhuo Chen wrote:
> > > Statements clearing AER error status in aer_enable_rootport() has the
> > > same function as pci_aer_raw_clear_status(). So we replace them, which
> > > has no functional changes.

> > > -	pci_read_config_dword(pdev, aer + PCI_ERR_ROOT_STATUS, &reg32);
> > > -	pci_write_config_dword(pdev, aer + PCI_ERR_ROOT_STATUS, reg32);
> > > -	pci_read_config_dword(pdev, aer + PCI_ERR_COR_STATUS, &reg32);
> > > -	pci_write_config_dword(pdev, aer + PCI_ERR_COR_STATUS, reg32);
> > > -	pci_read_config_dword(pdev, aer + PCI_ERR_UNCOR_STATUS, &reg32);
> > > -	pci_write_config_dword(pdev, aer + PCI_ERR_UNCOR_STATUS, reg32);
> > > +	pci_aer_raw_clear_status(pdev);
> > 
> > It's true that this is functionally equivalent.
> > 
> > But 20e15e673b05 ("PCI/AER: Add pci_aer_raw_clear_status() to
> > unconditionally clear Error Status") says pci_aer_raw_clear_status()
> > is only for use in the EDR path (this should have been included in the
> > function comment), so I think we should preserve that property and use
> > pci_aer_clear_status() here.
> > 
> > pci_aer_raw_clear_status() is the same as pci_aer_clear_status()
> > except it doesn't check pcie_aer_is_native().  And I'm pretty sure we
> > can't get to aer_enable_rootport() *unless* pcie_aer_is_native(),
> > because get_port_device_capability() checks the same thing, so they
> > should be equivalent here.
> > 
> Thanks Bjorn, this very detailed correction is helpful. By the way, 'only
> for use in the EDR path' obviously written in the function comments may be
> better. So far only commit log has included these.

Yes, definitely!  I goofed when I applied that patch without making
sure there was something in the function comment.

Bjorn