Re: [PATCH v2 5/9] PCI: pciehp: Move check for is_thunderbolt into a quirk

Ilpo Järvinen
2023-11-06T12:42:11Z

On Fri, 3 Nov 2023, Mario Limonciello wrote:

> commit 493fb50e958c ("PCI: pciehp: Assume NoCompl+ for Thunderbolt
> ports") added a check into pciehp code to explicitly set NoCompl+
> for all Intel Thunderbolt controllers, including those that don't
> need it.
>
> This overloaded the purpose of the `is_thunderbolt` member of
> `struct pci_device` because that means that any controller that
> identifies as thunderbolt would set NoCompl+ even if it doesn't
> suffer this deficiency. As that commit helpfully specifies all the
> controllers with the problem, move them into a PCI quirk.
>
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> ---
> drivers/pci/hotplug/pciehp_hpc.c | 6 +-----
> drivers/pci/quirks.c | 20 ++++++++++++++++++++
> include/linux/pci.h | 1 +
> 3 files changed, 22 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
> index fd713abdfb9f..23a92d681d1c 100644
> --- a/drivers/pci/hotplug/pciehp_hpc.c
> +++ b/drivers/pci/hotplug/pciehp_hpc.c
> @@ -991,11 +991,7 @@ struct controller *pcie_init(struct pcie_device *dev)
> if (pdev->hotplug_user_indicators)
> slot_cap &= ~(PCI_EXP_SLTCAP_AIP | PCI_EXP_SLTCAP_PIP);
>
> - /*
> - * We assume no Thunderbolt controllers support Command Complete events,
> - * but some controllers falsely claim they do.
> - */
> - if (pdev->is_thunderbolt)
> + if (pdev->no_command_complete)
> slot_cap |= PCI_EXP_SLTCAP_NCCS;
>
> ctrl->slot_cap = slot_cap;
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index eeec1d6f9023..4bbf6e33ca11 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -3807,6 +3807,26 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_CACTUS_RIDGE_4C
> DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_PORT_RIDGE,
> quirk_thunderbolt_hotplug_msi);
>
> +/*
> + * We assume no Thunderbolt controllers support Command Complete events,
> + * but some controllers falsely claim they do.

IMO, this wording makes little sense with the new code. How about taking
some text from the original commit's changelog:

/*
* Certain Thunderbolt 1 controllers falsely claim to support Command
* Completed events.
*/

The code change looks fine.

--
i.

> + */
> +static void quirk_thunderbolt_command_complete(struct pci_dev *pdev)
> +{
> + pdev->no_command_complete = 1;
> +}
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_LIGHT_RIDGE,
> + quirk_thunderbolt_command_complete);
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_EAGLE_RIDGE,
> + quirk_thunderbolt_command_complete);
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_LIGHT_PEAK,
> + quirk_thunderbolt_command_complete);
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_CACTUS_RIDGE_4C,
> + quirk_thunderbolt_command_complete);
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_CACTUS_RIDGE_2C,
> + quirk_thunderbolt_command_complete);
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_PORT_RIDGE,
> + quirk_thunderbolt_command_complete);
> #ifdef CONFIG_ACPI
> /*
> * Apple: Shutdown Cactus Ridge Thunderbolt controller.
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 530b0a360514..439c2dac8a3e 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -441,6 +441,7 @@ struct pci_dev {
> unsigned int is_hotplug_bridge:1;
> unsigned int shpc_managed:1; /* SHPC owned by shpchp */
> unsigned int is_thunderbolt:1; /* Thunderbolt controller */
> + unsigned int no_command_complete:1; /* No command completion */
> /*
> * Devices marked being untrusted are the ones that can potentially
> * execute DMA attacks and similar. They are typically connected
>