linux-kernel - Re: [PATCH v2] PCI/EDR: Clear PCIe Device Status errors after EDR error recovery

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Message-ID: <20230407215259.GA3825733@bhelgaas>
Date:   Fri, 7 Apr 2023 16:52:59 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        "Natu, Mahesh" <mahesh.natu@...el.com>
Subject: Re: [PATCH v2] PCI/EDR: Clear PCIe Device Status errors after EDR
 error recovery

On Fri, Apr 07, 2023 at 04:51:44PM -0500, Bjorn Helgaas wrote:
> I'll post a follow-up patch to add a couple comments there,
> too.

Comments I propose:


    PCI/EDR: Add edr_handle_event() comments
    
    EDR documentation is a bit sketchy.  Add a couple comments to
    edr_handle_event() about the devices involved.
    
    Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>

diff --git a/drivers/pci/pcie/edr.c b/drivers/pci/pcie/edr.c
index 87734e4c3c20..135ddb53661c 100644
--- a/drivers/pci/pcie/edr.c
+++ b/drivers/pci/pcie/edr.c
@@ -151,9 +151,17 @@ static void edr_handle_event(acpi_handle handle, u32 event, void *data)
 	if (event != ACPI_NOTIFY_DISCONNECT_RECOVER)
 		return;
 
+	/*
+	 * pdev itself is still present, but one or more of its child
+	 * devices have been disconnected (ACPI v6.3, sec 5.6.6).
+	 */
 	pci_info(pdev, "EDR event received\n");
 
-	/* Locate the port which issued EDR event */
+	/*
+	 * Locate the port that experienced the containment event.  pdev
+	 * may be that port or a parent of it (PCI Firmware r3.3, sec
+	 * 4.6.13).
+	 */
 	edev = acpi_dpc_port_get(pdev);
 	if (!edev) {
 		pci_err(pdev, "Firmware failed to locate DPC port\n");