linux-kernel - Re: [PATCH v3 1/2] PCI: pciehp: Add support for async hotplug with native AER and DPC/EDR

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Message-ID: <20230628132944.GB14276@wunner.de>
Date:   Wed, 28 Jun 2023 15:29:44 +0200
From:   Lukas Wunner <lukas@...ner.de>
To:     Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>
Cc:     Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        Bjorn Helgaas <bhelgaas@...gle.com>, oohall@...il.com,
        Mahesh J Salgaonkar <mahesh@...ux.ibm.com>,
        Yazen Ghannam <yazen.ghannam@....com>,
        Fontenot Nathan <Nathan.Fontenot@....com>
Subject: Re: [PATCH v3 1/2] PCI: pciehp: Add support for async hotplug with
 native AER and DPC/EDR

On Tue, Jun 27, 2023 at 10:48:37AM -0700, Smita Koralahalli wrote:
> On 6/22/2023 4:22 PM, Sathyanarayanan Kuppuswamy wrote:
> > On 6/21/23 11:51 AM, Smita Koralahalli wrote:
> > > +static void dpc_handle_surprise_removal(struct pci_dev *pdev)
> > > +{
> > > +	if (pdev->dpc_rp_extensions && dpc_wait_rp_inactive(pdev)) {
> > > +		pci_err(pdev, "failed to retrieve DPC root port on async remove\n");
> > > +		goto out;
> > > +	}
> > > +
> > > +	pci_aer_raw_clear_status(pdev);
> > > +	pci_clear_surpdn_errors(pdev);
> > > +
> > > +	pci_write_config_word(pdev, pdev->dpc_cap + PCI_EXP_DPC_STATUS,
> > > +			      PCI_EXP_DPC_STATUS_TRIGGER);
> > 
> > Don't you need to wait for the link to go down?
> 
> Yes will include, pcie_wait_for_link()..
> 
> Should this check be here or at the beginning of the function before we
> check pdev->dpc_rp_extensions?

I'd just use the same order as dpc_reset_link(), i.e. checking for
!pcie_wait_for_link() happens before the check for pdev->dpc_rp_extensions.

Thanks,

Lukas