On Sun, Jan 15, 2017 at 09:03:45PM +0100, Lukas Wunner wrote:
> We're about to allow runtime PM on Thunderbolt ports in
> pci_bridge_d3_possible() and unblock runtime PM for Thunderbolt host
> hotplug ports in pci_dev_check_d3cold(). In both cases we need to
> uniquely identify if a PCI device belongs to a Thunderbolt controller.
Sounds like "a device belongs to a Thunderbolt controller" means the
device is part of a Thunderbolt controller or part of the hierarchy
below it?
> We also have the need to detect presence of a Thunderbolt controller in
> drivers/platform/x86/apple-gmux.c because dual GPU MacBook Pros cannot
> switch external DP/HDMI ports between GPUs if they have Thunderbolt.
This series doesn't touch apple-gmux.c, and I don't know anything
about this MacBook Pro topology, so I can't tell why Thunderbolt is
relevant here.
> Furthermore, in multiple places in the DRM subsystem we need to detect
> whether a GPU is on-board or attached with Thunderbolt. As an example,
> Thunderbolt-attached GPUs shall not be registered with vga_switcheroo.
Why? The connection between vga_switcheroo and Thunderbolt is not
obvious, at least to this non-GPU person.
> Intel uses a Vendor-Specific Extended Capability (VSEC) with ID 0x1234
> on devices belonging to a Thunderbolt controller which allows us to
> recognize them.
>
> Detect presence of this VSEC on device probe and cache it in a newly
> added is_thunderbolt bit in struct pci_dev which can then be queried by
> pci_bridge_d3_possible(), pci_dev_check_d3cold(), apple-gmux and others.
>
> Cc: Andreas Noever <andreas.noever@xxxxxxxxx>
> Cc: Tomas Winkler <tomas.winkler@xxxxxxxxx>
> Cc: Amir Levy <amir.jer.levy@xxxxxxxxx>
> Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
> ---
> drivers/pci/pci.h | 2 ++
> drivers/pci/probe.c | 34 ++++++++++++++++++++++++++++++++++
> include/linux/pci.h | 1 +
> 3 files changed, 37 insertions(+)
>
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index cb17db242f30..45c2b8144911 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -3,6 +3,8 @@
>
> #define PCI_FIND_CAP_TTL 48
>
> +#define PCI_VSEC_ID_INTEL_TBT 0x1234 /* Thunderbolt */
> +
> extern const unsigned char pcie_link_speed[];
>
> bool pcie_cap_has_lnkctl(const struct pci_dev *dev);
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index e164b5c9f0f0..891a8fa1f9f6 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1206,6 +1206,37 @@ void set_pcie_hotplug_bridge(struct pci_dev *pdev)
> pdev->is_hotplug_bridge = 1;
> }
>
> +static void set_pcie_vendor_specific(struct pci_dev *dev)
This is very specific to Thunderbolt, so let's name it something that
conveys that information. The fact that we use a vendor-specific
capability to figure it out isn't really relevant in the caller.
> +{
> + int vsec = 0;
> + u32 header;
> +
> + while ((vsec = pci_find_next_ext_capability(dev, vsec,
> + PCI_EXT_CAP_ID_VNDR))) {
> + pci_read_config_dword(dev, vsec + PCI_VNDR_HEADER, &header);
> +
> + /* Is the device part of a Thunderbolt controller? */
> + if (dev->vendor == PCI_VENDOR_ID_INTEL &&
> + PCI_VNDR_HEADER_ID(header) == PCI_VSEC_ID_INTEL_TBT)
> + dev->is_thunderbolt = 1;
return;
> + }
> +
> + /*
> + * Is the device attached with Thunderbolt? Walk upwards and check for
> + * each encountered bridge if it's part of a Thunderbolt controller.
> + * Reaching the host bridge means dev is soldered to the mainboard.
> + */
> + if (!dev->is_thunderbolt) {
The "if" is unnecessary if you return above.
> + struct pci_dev *parent = dev;
> +
> + while ((parent = pci_upstream_bridge(parent)))
> + if (parent->is_thunderbolt) {
> + dev->is_thunderbolt = 1;
> + break;
> + }
> + }
> +}
> +
> /**
> * pci_ext_cfg_is_aliased - is ext config space just an alias of std config?
> * @dev: PCI device
> @@ -1358,6 +1389,9 @@ int pci_setup_device(struct pci_dev *dev)
> /* need to have dev->class ready */
> dev->cfg_size = pci_cfg_space_size(dev);
>
> + /* need to have dev->cfg_size ready */
> + set_pcie_vendor_specific(dev);
> +
> /* "Unknown power state" */
> dev->current_state = PCI_UNKNOWN;
>
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index e2d1a124216a..3c775e8498f1 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -358,6 +358,7 @@ struct pci_dev {
> unsigned int is_virtfn:1;
> unsigned int reset_fn:1;
> unsigned int is_hotplug_bridge:1;
> + unsigned int is_thunderbolt:1; /* part of Thunderbolt daisy chain */
> unsigned int __aer_firmware_first_valid:1;
> unsigned int __aer_firmware_first:1;
> unsigned int broken_intx_masking:1;
> --
> 2.11.0
>
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