4.19-stable review patch. If anyone has any objections, please let me know.
------------------
From: Lukas Wunner lukas@wunner.de
commit 70b70a4307cccebe91388337b1c85735ce4de6ff upstream.
struct pci_dev contains two flags which govern whether the device may suspend to D3cold:
* no_d3cold provides an opt-out for drivers (e.g. if a device is known to not wake from D3cold)
* d3cold_allowed provides an opt-out for user space (default is true, user space may set to false)
Since commit 9d26d3a8f1b0 ("PCI: Put PCIe ports into D3 during suspend"), the user space setting overwrites the driver setting. Essentially user space is trusted to know better than the driver whether D3cold is working.
That feels unsafe and wrong. Assume that the change was introduced inadvertently and do not overwrite no_d3cold when d3cold_allowed is modified. Instead, consider d3cold_allowed in addition to no_d3cold when choosing a suspend state for the device.
That way, user space may opt out of D3cold if the driver hasn't, but it may no longer force an opt in if the driver has opted out.
Fixes: 9d26d3a8f1b0 ("PCI: Put PCIe ports into D3 during suspend") Link: https://lore.kernel.org/r/b8a7f4af2b73f6b506ad8ddee59d747cbf834606.169502536... 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: Mario Limonciello mario.limonciello@amd.com Cc: stable@vger.kernel.org # v4.8+ Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/pci/pci-acpi.c | 2 +- drivers/pci/pci-sysfs.c | 5 +---- 2 files changed, 2 insertions(+), 5 deletions(-)
--- a/drivers/pci/pci-acpi.c +++ b/drivers/pci/pci-acpi.c @@ -496,7 +496,7 @@ static pci_power_t acpi_pci_choose_state { int acpi_state, d_max;
- if (pdev->no_d3cold) + if (pdev->no_d3cold || !pdev->d3cold_allowed) d_max = ACPI_STATE_D3_HOT; else d_max = ACPI_STATE_D3_COLD; --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -519,10 +519,7 @@ static ssize_t d3cold_allowed_store(stru return -EINVAL;
pdev->d3cold_allowed = !!val; - if (pdev->d3cold_allowed) - pci_d3cold_enable(pdev); - else - pci_d3cold_disable(pdev); + pci_bridge_d3_update(pdev);
pm_runtime_resume(dev);