linux-kernel - [PATCH] PCI: Clear PCI_STATUS when setting up the device

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Message-Id: <20220517043738.2308499-1-kai.heng.feng@canonical.com>
Date:   Tue, 17 May 2022 12:37:38 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     bhelgaas@...gle.com
Cc:     Kai-Heng Feng <kai.heng.feng@...onical.com>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] PCI: Clear PCI_STATUS when setting up the device

We are seeing Master Abort bit is set on Intel I350 ethernet device and its
root port right after boot, probably happened during BIOS phase:

00:06.0 PCI bridge [0604]: Intel Corporation Device [8086:464d] (rev 05) (prog-if 00 [Normal decode])
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort+ >SERR- <PERR- INTx-

6e:00.0 Ethernet controller [0200]: Intel Corporation I350 Gigabit Network Connection [8086:1521] (rev 01)
        Subsystem: Intel Corporation Ethernet Server Adapter I350-T2 [8086:00a2]
        Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort+ >SERR- <PERR- INTx-

6e:00.1 Ethernet controller [0200]: Intel Corporation I350 Gigabit Network Connection [8086:1521] (rev 01)
        Subsystem: Intel Corporation Ethernet Server Adapter I350-T2 [8086:00a2]
        Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort+ >SERR- <PERR- INTx-

And the Master Abort bit is cleared after S3.

Since there's no functional impact found, clear the PCI_STATUS to treat
it anew at setting up.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=215989
Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
---
 drivers/pci/probe.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 17a969942d370..414f659dc8735 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1890,6 +1890,9 @@ int pci_setup_device(struct pci_dev *dev)
 
 	dev->broken_intx_masking = pci_intx_mask_broken(dev);
 
+	/* Clear errors left from system firmware */
+	pci_write_config_word(dev, PCI_STATUS, 0xffff);
+
 	switch (dev->hdr_type) {		    /* header type */
 	case PCI_HEADER_TYPE_NORMAL:		    /* standard header */
 		if (class == PCI_CLASS_BRIDGE_PCI)
-- 
2.34.1