This is a note to let you know that I've just added the patch titled
PCI/PM: Observe reset delay irrespective of bridge_d3
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
pci-pm-observe-reset-delay-irrespective-of-bridge_d3.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 8ef0217227b42e2c34a18de316cee3da16c9bf1e Mon Sep 17 00:00:00 2001
From: Lukas Wunner <lukas@xxxxxxxxx>
Date: Sun, 15 Jan 2023 09:20:31 +0100
Subject: PCI/PM: Observe reset delay irrespective of bridge_d3
From: Lukas Wunner <lukas@xxxxxxxxx>
commit 8ef0217227b42e2c34a18de316cee3da16c9bf1e upstream.
If a PCI bridge is suspended to D3cold upon entering system sleep,
resuming it entails a Fundamental Reset per PCIe r6.0 sec 5.8.
The delay prescribed after a Fundamental Reset in PCIe r6.0 sec 6.6.1
is sought to be observed by:
pci_pm_resume_noirq()
pci_pm_bridge_power_up_actions()
pci_bridge_wait_for_secondary_bus()
However, pci_bridge_wait_for_secondary_bus() bails out if the bridge_d3
flag is not set. That flag indicates whether a bridge is allowed to
suspend to D3cold at *runtime*.
Hence *no* delay is observed on resume from system sleep if runtime
D3cold is forbidden. That doesn't make any sense, so drop the bridge_d3
check from pci_bridge_wait_for_secondary_bus().
The purpose of the bridge_d3 check was probably to avoid delays if a
bridge remained in D0 during suspend. However the sole caller of
pci_bridge_wait_for_secondary_bus(), pci_pm_bridge_power_up_actions(),
is only invoked if the previous power state was D3cold. Hence the
additional bridge_d3 check seems superfluous.
Fixes: ad9001f2f411 ("PCI/PM: Add missing link delays required by the PCIe spec")
Link: https://lore.kernel.org/r/eb37fa345285ec8bacabbf06b020b803f77bdd3d.1673769517.git.lukas@xxxxxxxxx
Tested-by: Ravi Kishore Koppuravuri <ravi.kishore.koppuravuri@xxxxxxxxx>
Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Reviewed-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v5.5+
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/pci/pci.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4902,7 +4902,7 @@ void pci_bridge_wait_for_secondary_bus(s
if (pci_dev_is_disconnected(dev))
return;
- if (!pci_is_bridge(dev) || !dev->bridge_d3)
+ if (!pci_is_bridge(dev))
return;
down_read(&pci_bus_sem);
Patches currently in stable-queue which might be from lukas@xxxxxxxxx are
queue-5.15/pci-hotplug-allow-marking-devices-as-disconnected-during-bind-unbind.patch
queue-5.15/pci-pm-observe-reset-delay-irrespective-of-bridge_d3.patch
