linux-kernel - Re: [PATCH V4 7/7] PCI: Handle link reset via hotplug if supported

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Message-ID: <CAHp75VcSapu6Q-eNhbbSQ6hSV=OF0pS=mXsdHZxascst5OLxCQ@mail.gmail.com>
Date:   Sat, 30 Jun 2018 00:39:03 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Sinan Kaya <okaya@...eaurora.org>
Cc:     linux-pci@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Oza Pawandeep <poza@...eaurora.org>,
        Keith Busch <keith.busch@...el.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V4 7/7] PCI: Handle link reset via hotplug if supported

On Thu, Jun 28, 2018 at 10:31 PM, Sinan Kaya <okaya@...eaurora.org> wrote:
> If a bridge supports hotplug and observes a PCIe fatal error, the following
> events happen:
>
> 1. AER driver removes the devices from PCI tree on fatal error
> 2. AER driver brings down the link by issuing a secondary bus reset waits
> for the link to come up.
> 3. Hotplug driver observes a link down interrupt
> 4. Hotplug driver tries to remove the devices waiting for the rescan lock
> but devices are already removed by the AER driver and AER driver is waiting
> for the link to come back up.
> 5. AER driver tries to re-enumerate devices after polling for the link
> state to go up.
> 6. Hotplug driver obtains the lock and tries to remove the devices again.
>
> If a bridge is a hotplug capable bridge, bounce the error handling to the
> hotplug driver so that hotplug driver can mask link up/down interrupts
> while performing a secondary bus reset.

> +static pci_ers_result_t pciehp_reset_link(struct pci_dev *pdev)
> +{
> +       struct pcie_device *pciedev;
> +       struct controller *ctrl;
> +       struct device *devhp;
> +       struct slot *slot;
> +       int rc;
> +
> +       devhp = pcie_port_find_device(pdev, PCIE_PORT_SERVICE_HP);
> +       pciedev = to_pcie_device(devhp);
> +       ctrl = get_service_data(pciedev);
> +       slot = ctrl->slot;
> +
> +       rc = reset_slot(slot->hotplug_slot, 0);
> +
> +       return !rc ? PCI_ERS_RESULT_RECOVERED : PCI_ERS_RESULT_DISCONNECT;

Would it be better to

return rc ? ..._DISCONNECT : ..._RECOVERED; ?

> +}



-- 
With Best Regards,
Andy Shevchenko