linux-kernel - Re: [PATCH pci-next] pci/edr: Ignore Surprise Down error on hot removal

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Date: Mon, 4 Mar 2024 12:58:44 +0100
From: Lukas Wunner <lukas@...ner.de>
To: Ethan Zhao <haifeng.zhao@...ux.intel.com>
Cc: bhelgaas@...gle.com, Smita.KoralahalliChannabasappa@....com,
	ilpo.jarvinen@...ux.intel.com,
	sathyanarayanan.kuppuswamy@...ux.intel.com,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	kbusch@...nel.org
Subject: Re: [PATCH pci-next] pci/edr: Ignore Surprise Down error on hot
 removal

On Mon, Mar 04, 2024 at 04:08:19AM -0500, Ethan Zhao wrote:
> Per PCI firmware spec r3.3 sec 4.6.12, for firmware first mode DPC
> handling path, FW should clear UC errors logged by port and bring link
> out of DPC, but because of ambiguity of wording in the spec, some BIOSes
> doesn't clear the surprise down error and the error bits in pci status,
> still notify OS to handle it. thus following trick is needed in EDR when
> double reporting (hot removal interrupt && dpc notification) is hit.

Please provide more detailed information about the hardware and BIOS
affected by this.


> -static void dpc_handle_surprise_removal(struct pci_dev *pdev)
> +bool  dpc_handle_surprise_removal(struct pci_dev *pdev)
>  {
> +	if (!dpc_is_surprise_removal(pdev))
> +		return false;

This change of moving dpc_is_surprise_removal() into
dpc_handle_surprise_removal() seems unrelated to the problem at hand.

Please drop it if it's unnecessary to fix the issue.


> --- a/drivers/pci/pcie/edr.c
> +++ b/drivers/pci/pcie/edr.c
> @@ -184,6 +184,9 @@ static void edr_handle_event(acpi_handle handle, u32 event, void *data)
>  		goto send_ost;
>  	}
>  
> +	if (dpc_handle_surprise_removal(edev))
> +		goto send_ost;
> +
>  	dpc_process_error(edev);
>  	pci_aer_raw_clear_status(edev);

This seems to be the only necessary change.  Please reduce the
patch to contain only it and no other refactoring.

Please capitalize the "PCI/EDR: " prefix in the subject and add
a Fixes tag.

Thanks,

Lukas