d219b19e1f
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@wunner.de
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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
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Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
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https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.