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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 /drivers/pci/pci.h | |
parent | 8ccd1e5162c96462ffddff2a6f7119f3ab6b2a9a (diff) | |
download | linux-8531e283bee66050734fb0e89d53e85fd5ce24a4.tar.bz2 |
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
Diffstat (limited to 'drivers/pci/pci.h')
-rw-r--r-- | drivers/pci/pci.h | 2 |
1 files changed, 2 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); |