https://bugzilla.kernel.org/show_bug.cgi?id=219629
--- Comment #6 from Evert Vorster (evors...@gmail.com) ---
It turns out that I had a little more time on my hands.
Here is the output of the kernel bisect:
[code]
[evert@Evert linux-mainline]$ git bisect good
665745f274870c921020f610e2c99a3b1613519b is the first bad commit
commit 665745f274870c921020f610e2c99a3b1613519b
Author: Ilpo Järvinen <ilpo.jarvi...@linux.intel.com>
Date: Fri Oct 18 17:47:52 2024 +0300
PCI/bwctrl: Re-add BW notification portdrv as PCIe BW controller
This mostly reverts the commit b4c7d2076b4e ("PCI/LINK: Remove bandwidth
notification"). An upcoming commit extends this driver building PCIe
bandwidth controller on top of it.
PCIe bandwidth notifications were first added in the commit e8303bb7a75c
("PCI/LINK: Report degraded links via link bandwidth notification") but
later had to be removed. The significant changes compared with the old
bandwidth notification driver include:
1) Don't print the notifications into kernel log, just keep the Link
Speed cached in struct pci_bus updated. While somewhat unfortunate,
the log spam was the source of complaints that eventually lead to
the removal of the bandwidth notifications driver (see the links
below for further information).
2) Besides the Link Bandwidth Management Interrupt, also enable Link
Autonomous Bandwidth Interrupt to cover the other source of bandwidth
changes.
3) Handle Link Speed updates robustly. Refresh the cached Link Speed
when enabling Bandwidth Notification Interrupts, and solve the race
between Link Speed read and LBMS/LABS update in
pcie_bwnotif_irq_thread().
4) Use concurrency safe LNKCTL RMW operations.
5) The driver is now called PCIe bwctrl (bandwidth controller) instead
of just bandwidth notifications because of increased scope and
functionality within the driver.
6) Coexist with the Target Link Speed quirk in pcie_failed_link_retrain().
Provide LBMS counting API for it.
7) Tweaks to variable/functions names for consistency and length reasons.
Bandwidth Notifications enable the cur_bus_speed in the struct pci_bus to
keep track PCIe Link Speed changes.
[bhelgaas: This is based on previous work by Alexandru Gagniuc
<mr.nuke...@gmail.com>; see e8303bb7a75c ("PCI/LINK: Report degraded links
via link bandwidth notification")]
Link:
https://lore.kernel.org/r/20241018144755.7875-7-ilpo.jarvi...@linux.intel.com
Link:
https://lore.kernel.org/all/20190429185611.121751-1-helg...@kernel.org/
Link:
https://lore.kernel.org/linux-pci/20190501142942.26972-1-keith.bu...@intel.com/
Link: https://lore.kernel.org/linux-pci/20200115221008.ga191...@google.com/
Suggested-by: Lukas Wunner <lu...@wunner.de> # Building bwctrl on top of
bwnotif
Signed-off-by: Ilpo Järvinen <ilpo.jarvi...@linux.intel.com>
[bhelgaas: squash fix to drop IRQF_ONESHOT and convert to hardirq handler:
https://lore.kernel.org/r/20241115165717.15233-1-ilpo.jarvi...@linux.intel.com]
Signed-off-by: Bjorn Helgaas <bhelg...@google.com>
Tested-by: Stefan Wahren <wahre...@gmx.net>
Reviewed-by: Jonathan Cameron <jonathan.came...@huawei.com>
MAINTAINERS | 6 ++++
drivers/pci/hotplug/pciehp_ctrl.c | 5 ++++
drivers/pci/pci.c | 2 +-
drivers/pci/pci.h | 11 +++++++
drivers/pci/pcie/Makefile | 2 +-
drivers/pci/pcie/bwctrl.c | 186
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
drivers/pci/pcie/portdrv.c | 9 +++---
drivers/pci/pcie/portdrv.h | 6 ++--
drivers/pci/quirks.c | 9 +++++-
include/linux/pci.h | 2 ++
10 files changed, 229 insertions(+), 9 deletions(-)
create mode 100644 drivers/pci/pcie/bwctrl.c
[evert@Evert linux-mainline]$
[/code]
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