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
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 8dd38e6..4dbf9f9 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 dfc9a27..90592d4 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1208,6 +1208,24 @@
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 @@
/* 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;