From: Lukas Wunner <lukas@wunner.de>
To: Bjorn Helgaas <helgaas@kernel.org>, linux-pci@vger.kernel.org
Cc: Keith Busch <kbusch@kernel.org>, Ashok Raj <ashok.raj@intel.com>,
Sathyanarayanan Kuppuswamy
<sathyanarayanan.kuppuswamy@linux.intel.com>,
Ravi Kishore Koppuravuri <ravi.kishore.koppuravuri@intel.com>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Sheng Bi <windy.bi.enflame@gmail.com>,
Stanislav Spassov <stanspas@amazon.de>,
Yang Su <yang.su@linux.alibaba.com>
Subject: [PATCH 1/3] PCI/PM: Observe reset delay irrespective of bridge_d3
Date: Sat, 31 Dec 2022 19:33:37 +0100 [thread overview]
Message-ID: <ec4761d5e7f7a3258d9a37284571b9eb1c2e0a4a.1672511017.git.lukas@wunner.de> (raw)
In-Reply-To: <cover.1672511016.git.lukas@wunner.de>
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")
Tested-by: Ravi Kishore Koppuravuri <ravi.kishore.koppuravuri@intel.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: stable@vger.kernel.org # v5.5+
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
---
drivers/pci/pci.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index fba95486caaf..f43f3e84f634 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4964,7 +4964,7 @@ void pci_bridge_wait_for_secondary_bus(struct pci_dev *dev)
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);
--
2.39.0
next prev parent reply other threads:[~2022-12-31 18:36 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-31 18:33 [PATCH 0/3] PCI reset delay fixes Lukas Wunner
2022-12-31 18:33 ` Lukas Wunner [this message]
2023-01-03 19:50 ` [PATCH 1/3] PCI/PM: Observe reset delay irrespective of bridge_d3 Sathyanarayanan Kuppuswamy
2022-12-31 18:33 ` [PATCH 2/3] PCI: Unify delay handling for reset and resume Lukas Wunner
2023-01-03 19:50 ` Sathyanarayanan Kuppuswamy
2023-01-12 22:31 ` Bjorn Helgaas
2022-12-31 18:33 ` [PATCH 3/3] PCI/DPC: Await readiness of secondary bus after reset Lukas Wunner
2023-01-03 19:49 ` Sathyanarayanan Kuppuswamy
2023-01-12 22:35 ` Bjorn Helgaas
[not found] ` <15135d89-0515-d965-567b-79b3eca236e6@linux.alibaba.com>
2023-01-13 3:06 ` Bjorn Helgaas
2023-01-13 10:18 ` Lukas Wunner
2023-01-13 9:10 ` Lukas Wunner
2023-01-03 11:09 ` [PATCH 0/3] PCI reset delay fixes Mika Westerberg
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