On 12/14/2023 03:00, Rafael J. Wysocki wrote:
On Thu, Dec 14, 2023 at 4:46 AM Kai-Heng Feng
<kai.heng.feng@xxxxxxxxxxxxx> wrote:
Hi Mario and Rafael,
On Thu, Dec 14, 2023 at 2:46 AM Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote:
On Wed, Dec 13, 2023 at 7:42 PM Mario Limonciello
<mario.limonciello@xxxxxxx> wrote:
On 12/13/2023 12:38, Rafael J. Wysocki wrote:
On Wed, Dec 13, 2023 at 7:27 PM Mario Limonciello
<mario.limonciello@xxxxxxx> wrote:
When a system is being powered off it's important that PCIe ports
have been put into D3cold as there is no other software to turn
off the devices at S5.
If PCIe ports are left in D0 then any GPIOs toggled by the ACPI
power resources may be left enabled and devices may consume excess
power.
Isn't that a platform firmware issue?
It is the responsibility of the platform firmware to properly put the
platform into S5, including power removal from devices that are not
armed for power-on.
The specific issues that triggered this series were tied to the PCIe
ports for dGPUs. There is a GPIO that is toggled by _ON or _OFF.
Windows calls _OFF as part of S5..
I see.
Cc: mpearson-lenovo@xxxxxxxxx
Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
---
drivers/pci/pcie/portdrv.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/drivers/pci/pcie/portdrv.c b/drivers/pci/pcie/portdrv.c
index 14a4b89a3b83..08238680c481 100644
--- a/drivers/pci/pcie/portdrv.c
+++ b/drivers/pci/pcie/portdrv.c
@@ -734,9 +734,14 @@ static void pcie_portdrv_remove(struct pci_dev *dev)
static void pcie_portdrv_shutdown(struct pci_dev *dev)
{
if (pci_bridge_d3_possible(dev)) {
- pm_runtime_forbid(&dev->dev);
- pm_runtime_get_noresume(&dev->dev);
- pm_runtime_dont_use_autosuspend(&dev->dev);
+ /* whole hierarchy goes into a low power state for S5 */
+ if (system_state == SYSTEM_POWER_OFF) {
+ pci_set_power_state(dev, PCI_D3cold);
+ } else {
+ pm_runtime_forbid(&dev->dev);
+ pm_runtime_get_noresume(&dev->dev);
+ pm_runtime_dont_use_autosuspend(&dev->dev);
+ }
}
Wouldn't it be better to remove power from the port after running the
code below?
Yes; I think you're right. I'll do some more testing with this.
pcie_port_device_remove(dev);
--
IIRC, to do this all properly, you'd need to rework the shutdown path
to look like the hibernation power-off one. Or even use the latter
for shutdown?
There was no reason to do that till now, so it has not been done, but
it looks like you have one.
I am working on exactly same thing but with a different approach.
Because this is needed for more than just PCI devices.
I haven't written a proper commit message yet, but the implementation
is quite simple:
As I said, doing this properly requires something like the hibernation
power-off transition to be carried out for S5.
I think that the existing hibernation power-off code can be used as-is
for this purpose even.
I feel Rafael is right here that unifying the hibernation and shutdown
paths is the right direction. Our team just double checked the
"unpatched" Linux S4 measurements on a system that otherwise had
problems with S5 and they show the same decreases in power my patch
series showed.
KH,
I'm going to be OOO for a while with the holidays around the corner and
some personal time. If you end up working on some patches to unify the
S4/S5 codepaths CC me on them and I'll look when I'm back from my leave.
Thanks,
