On Tue, Apr 16, 2024 at 12:32:24PM +0800, Kai-Heng Feng wrote:
> When the power rail gets cut off, the hardware can create some electric
> noise on the link that triggers AER. If IRQ is shared between AER with
> PME, such AER noise will cause a spurious wakeup on system suspend.
>
> When the power rail gets back, the firmware of the device resets itself
> and can create unexpected behavior like sending PTM messages. For this
> case, the driver will always be too late to toggle off features should
> be disabled.
>
> As Per PCIe Base Spec 5.0, section 5.2, titled "Link State Power
> Management", TLP and DLLP transmission are disabled for a Link in L2/L3
> Ready (D3hot), L2 (D3cold with aux power) and L3 (D3cold) states. So if
> the power will be turned off during suspend process, disable AER service
> and re-enable it during the resume process. This should not affect the
> basic functionality.
>
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=209149
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=216295
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=218090
> Signed-off-by: Kai-Heng Feng <kai.heng.f...@canonical.com>
Thanks for reviving this series. I tried follow the history about
this, but there are at least two series that were very similar and I
can't put it all together.
> ---
> v8:
> - Add more bug reports.
>
> v7:
> - Wording
> - Disable AER completely (again) if power will be turned off
>
> v6:
> v5:
> - Wording.
>
> v4:
> v3:
> - No change.
>
> v2:
> - Only disable AER IRQ.
> - No more check on PME IRQ#.
> - Use helper.
>
> drivers/pci/pcie/aer.c | 25 +++++++++++++++++++++++++
> 1 file changed, 25 insertions(+)
>
> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> index ac6293c24976..bea7818c2d1b 100644
> --- a/drivers/pci/pcie/aer.c
> +++ b/drivers/pci/pcie/aer.c
> @@ -28,6 +28,7 @@
> #include <linux/delay.h>
> #include <linux/kfifo.h>
> #include <linux/slab.h>
> +#include <linux/suspend.h>
> #include <acpi/apei.h>
> #include <acpi/ghes.h>
> #include <ras/ras_event.h>
> @@ -1497,6 +1498,28 @@ static int aer_probe(struct pcie_device *dev)
> return 0;
> }
>
> +static int aer_suspend(struct pcie_device *dev)
> +{
> + struct aer_rpc *rpc = get_service_data(dev);
> + struct pci_dev *pdev = rpc->rpd;
> +
> + if (pci_ancestor_pr3_present(pdev) || pm_suspend_via_firmware())
> + aer_disable_rootport(rpc);
Why do we check pci_ancestor_pr3_present(pdev) and
pm_suspend_via_firmware()? I'm getting pretty convinced that we need
to disable AER interrupts on suspend in general. I think it will be
better if we do that consistently on all platforms, not special cases
based on details of how we suspend.
Also, why do we use aer_disable_rootport() instead of just
aer_disable_irq()? I think it's the interrupt that causes issues on
suspend. I see that there *were* some versions that used
aer_disable_irq(), but I can't find the reason it changed.
> +
> + return 0;
> +}
> +
> +static int aer_resume(struct pcie_device *dev)
> +{
> + struct aer_rpc *rpc = get_service_data(dev);
> + struct pci_dev *pdev = rpc->rpd;
> +
> + if (pci_ancestor_pr3_present(pdev) || pm_resume_via_firmware())
> + aer_enable_rootport(rpc);
> +
> + return 0;
> +}
> +
> /**
> * aer_root_reset - reset Root Port hierarchy, RCEC, or RCiEP
> * @dev: pointer to Root Port, RCEC, or RCiEP
> @@ -1561,6 +1584,8 @@ static struct pcie_port_service_driver aerdriver = {
> .service = PCIE_PORT_SERVICE_AER,
>
> .probe = aer_probe,
> + .suspend = aer_suspend,
> + .resume = aer_resume,
> .remove = aer_remove,
> };
>
> --
> 2.34.1
>
