From 8531e283bee66050734fb0e89d53e85fd5ce24a4 Mon Sep 17 00:00:00 2001 From: Lukas Wunner Date: Fri, 10 Mar 2017 21:23:45 +0100 Subject: 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 Cc: Michael Jamet Cc: Tomas Winkler Cc: Amir Levy Acked-by: Bjorn Helgaas Signed-off-by: Lukas Wunner Link: http://patchwork.freedesktop.org/patch/msgid/0ab165a4a35c0b60f29d4c306c653ead14fcd8f9.1489145162.git.lukas@wunner.de --- drivers/pci/pci.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'drivers/pci/pci.h') 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); -- cgit v1.2.3