From: Lukas Wunner lukas@wunner.de
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.167376951... Tested-by: Ravi Kishore Koppuravuri ravi.kishore.koppuravuri@intel.com Signed-off-by: Lukas Wunner lukas@wunner.de Signed-off-by: Bjorn Helgaas bhelgaas@google.com Reviewed-by: Mika Westerberg mika.westerberg@linux.intel.com Reviewed-by: Kuppuswamy Sathyanarayanan sathyanarayanan.kuppuswamy@linux.intel.com Cc: stable@vger.kernel.org # v5.5+ Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/pci/pci.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -4957,7 +4957,7 @@ 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);