linux-kernel - Re: [PATCH v3 1/1] PCI/ERR: Fix reset logic in pcie_do

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Message-ID: <44f0cac5-8deb-1169-eb6d-93ac4889fe7e@kernel.org>
Date:   Fri, 25 Sep 2020 14:30:21 -0400
From:   Sinan Kaya <okaya@...nel.org>
To:     "Kuppuswamy, Sathyanarayanan" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        Bjorn Helgaas <helgaas@...nel.org>
Cc:     bhelgaas@...gle.com, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, ashok.raj@...el.com,
        Jay Vosburgh <jay.vosburgh@...onical.com>
Subject: Re: [PATCH v3 1/1] PCI/ERR: Fix reset logic in pcie_do_recovery()
 call

On 9/25/2020 2:16 PM, Kuppuswamy, Sathyanarayanan wrote:
>>
>> If this is a too involved change, DPC driver should restore state
>> when hotplug is not supported.
> Yes. we can add a condition for hotplug capability check.
>>
>> DPC driver should be self-sufficient by itself.
>>

Sounds good.

>>> Also for non-fatal errors, if reset is requested then we still need
>>> some kind of bus reset call here
>>
>> DPC should handle both fatal and non-fatal cases
> Currently DPC is only triggered for FATAL errors.
>  and cause a bus reset

Thanks for the heads up.
This seems to have changed since I looked at the DPC code.

>> in hardware already before triggering an interrupt.
> Error recovery is not triggered only DPC driver. AER also uses the
> same error recovery code. If DPC is not supported, then we still need
> reset logic.

It sounds like we are cross-talking two issues.

1. no state restore on DPC after FATAL error.
Let's fix this.

2. no bus reset on NON_FATAL error through AER driver path.
This already tells me that you need to split your change into
multiple patches.

Let's talk about this too. bus reset should be triggered via
AER driver before informing the recovery.

	if (status == PCI_ERS_RESULT_NEED_RESET) {
		/*
		 * TODO: Should call platform-specific
		 * functions to reset slot before calling
		 * drivers' slot_reset callbacks?
		 */
		status = PCI_ERS_RESULT_RECOVERED;
		pci_dbg(dev, "broadcast slot_reset message\n");
		pci_walk_bus(bus, report_slot_reset, &status);
	}