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PCI/bwctrl: Disable BW controller on Intel P45 using a quirk

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The commit 665745f274 ("PCI/bwctrl: Re-add BW notification portdrv as
PCIe BW controller") was found to lead to a boot hang on a Intel P45
system. Testing without setting Link Bandwidth Management Interrupt Enable
(LBMIE) and Link Autonomous Bandwidth Interrupt Enable (LABIE) (PCIe r7.0,
sec 7.5.3.7) in bwctrl allowed system to come up.

P45 is a very old chipset and supports only up to gen2 PCIe, so not having
bwctrl does not seem a huge deficiency.

Add no_bw_notif in struct pci_dev and quirk Intel P45 Root Port with it.

Reported-by: Adam Stylinski <kungfujesus06@gmail.com>
Link: https://lore.kernel.org/linux-pci/aUCt1tHhm_-XIVvi@eggsbenedict/
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Adam Stylinski <kungfujesus06@gmail.com>
Link: https://patch.msgid.link/20260116131513.2359-1-ilpo.jarvinen@linux.intel.com
This commit is contained in:
Ilpo Järvinen
2026-01-16 15:15:12 +02:00
committed by Bjorn Helgaas
parent 8f0b4cce44
commit 46a9f70e93
3 changed files with 14 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
drivers/pci/pcie/bwctrl.c
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@@ -250,6 +250,9 @@ static int pcie_bwnotif_probe(struct pcie_device *srv)
struct pci_dev *port = srv->port;
int ret;
if (port->no_bw_notif)
return -ENODEV;
/* Can happen if we run out of bus numbers during enumeration. */
if (!port->subordinate)
return -ENODEV;

10
drivers/pci/quirks.c
View File

@@ -1359,6 +1359,16 @@ static void quirk_transparent_bridge(struct pci_dev *dev)
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82380FB, quirk_transparent_bridge);
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_TOSHIBA, 0x605, quirk_transparent_bridge);
/*
* Enabling Link Bandwidth Management Interrupts (BW notifications) can cause
* boot hangs on P45.
*/
static void quirk_p45_bw_notifications(struct pci_dev *dev)
{
dev->no_bw_notif = 1;
}
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x2e21, quirk_p45_bw_notifications);
/*
* Common misconfiguration of the MediaGX/Geode PCI master that will reduce
* PCI bandwidth from 70MB/s to 25MB/s. See the GXM/GXLV/GX1 datasheets

1
include/linux/pci.h
View File

@@ -406,6 +406,7 @@ struct pci_dev {
user sysfs */
unsigned int clear_retrain_link:1; /* Need to clear Retrain Link
bit manually */
unsigned int no_bw_notif:1; /* BW notifications may cause issues */
unsigned int d3hot_delay; /* D3hot->D0 transition time in ms */
unsigned int d3cold_delay; /* D3cold->D0 transition time in ms */