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author | Lukas Wunner <lukas@wunner.de> | 2017-03-10 21:23:45 +0100 |
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committer | Lukas Wunner <lukas@wunner.de> | 2017-03-30 22:42:30 +0200 |
commit | 8531e283bee66050734fb0e89d53e85fd5ce24a4 (patch) | |
tree | eddfeb48ca8ce269acd8a0dfcacd4c1b13b36dde | |
parent | MAINTAINERS: Add Lukas Wunner as reviewer for vga_switcheroo (diff) | |
download | linux-8531e283bee66050734fb0e89d53e85fd5ce24a4.tar.xz linux-8531e283bee66050734fb0e89d53e85fd5ce24a4.zip |
PCI: Recognize Thunderbolt devices
Detect on probe whether a PCI device is part of a Thunderbolt controller.
Intel uses a Vendor-Specific Extended Capability (VSEC) with ID 0x1234
on such devices. Detect presence of this VSEC and cache it in a newly
added is_thunderbolt bit in struct pci_dev.
Also, add a helper to check whether a given PCI device is situated on a
Thunderbolt daisy chain (i.e., below a PCI device with is_thunderbolt
set).
The necessity arises from the following:
* If an external Thunderbolt GPU is connected to a dual GPU laptop,
that GPU is currently registered with vga_switcheroo even though it
can neither drive the laptop's panel nor be powered off by the
platform. To vga_switcheroo it will appear as if two discrete
GPUs are present. As a result, when the external GPU is runtime
suspended, vga_switcheroo will cut power to the internal discrete GPU
which may not be runtime suspended at all at this moment. The
solution is to not register external GPUs with vga_switcheroo, which
necessitates a way to recognize if they're on a Thunderbolt daisy
chain.
* Dual GPU MacBook Pros introduced 2011+ can no longer switch external
DisplayPort ports between GPUs. (They're no longer just used for DP
but have become combined DP/Thunderbolt ports.) The driver to switch
the ports, drivers/platform/x86/apple-gmux.c, needs to detect presence
of a Thunderbolt controller and, if found, keep external ports
permanently switched to the discrete GPU.
v2: Make kerneldoc for pci_is_thunderbolt_attached() more precise,
drop portion of commit message pertaining to separate series.
(Bjorn Helgaas)
Cc: Andreas Noever <andreas.noever@gmail.com>
Cc: Michael Jamet <michael.jamet@intel.com>
Cc: Tomas Winkler <tomas.winkler@intel.com>
Cc: Amir Levy <amir.jer.levy@intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: http://patchwork.freedesktop.org/patch/msgid/0ab165a4a35c0b60f29d4c306c653ead14fcd8f9.1489145162.git.lukas@wunner.de
-rw-r--r-- | drivers/pci/pci.h | 2 | ||||
-rw-r--r-- | drivers/pci/probe.c | 21 | ||||
-rw-r--r-- | include/linux/pci.h | 23 |
3 files changed, 46 insertions, 0 deletions
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h index 8dd38e69d6f2..4dbf9f96ae5b 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 dfc9a2794141..90592d424e9b 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -1208,6 +1208,24 @@ void set_pcie_hotplug_bridge(struct pci_dev *pdev) pdev->is_hotplug_bridge = 1; } +static void set_pcie_thunderbolt(struct pci_dev *dev) +{ + 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; + } + } +} + /** * pci_ext_cfg_is_aliased - is ext config space just an alias of std config? * @dev: PCI device @@ -1360,6 +1378,9 @@ 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_thunderbolt(dev); + /* "Unknown power state" */ dev->current_state = PCI_UNKNOWN; diff --git a/include/linux/pci.h b/include/linux/pci.h index eb3da1a04e6c..5948cfdc984e 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; /* Thunderbolt controller */ unsigned int __aer_firmware_first_valid:1; unsigned int __aer_firmware_first:1; unsigned int broken_intx_masking:1; @@ -2160,6 +2161,28 @@ static inline bool pci_ari_enabled(struct pci_bus *bus) return bus->self && bus->self->ari_enabled; } +/** + * pci_is_thunderbolt_attached - whether device is on a Thunderbolt daisy chain + * @pdev: PCI device to check + * + * Walk upwards from @pdev and check for each encountered bridge if it's part + * of a Thunderbolt controller. Reaching the host bridge means @pdev is not + * Thunderbolt-attached. (But rather soldered to the mainboard usually.) + */ +static inline bool pci_is_thunderbolt_attached(struct pci_dev *pdev) +{ + struct pci_dev *parent = pdev; + + if (pdev->is_thunderbolt) + return true; + + while ((parent = pci_upstream_bridge(parent))) + if (parent->is_thunderbolt) + return true; + + return false; +} + /* provide the legacy pci_dma_* API */ #include <linux/pci-dma-compat.h> |