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authorLukas Wunner <lukas@wunner.de>2017-03-10 23:23:45 +0300
committerLukas Wunner <lukas@wunner.de>2017-03-30 23:42:30 +0300
commit8531e283bee66050734fb0e89d53e85fd5ce24a4 (patch)
treeeddfeb48ca8ce269acd8a0dfcacd4c1b13b36dde /include
parent8ccd1e5162c96462ffddff2a6f7119f3ab6b2a9a (diff)
downloadlinux-8531e283bee66050734fb0e89d53e85fd5ce24a4.tar.xz
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 'include')
-rw-r--r--include/linux/pci.h23
1 files changed, 23 insertions, 0 deletions
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>