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Commit 8531e283 authored by Lukas Wunner's avatar Lukas Wunner
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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: default avatarBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: default avatarLukas Wunner <lukas@wunner.de>
Link: http://patchwork.freedesktop.org/patch/msgid/0ab165a4a35c0b60f29d4c306c653ead14fcd8f9.1489145162.git.lukas@wunner.de
parent 8ccd1e51

drivers/pci/pci.h

+2 −0
Original line number Diff line number Diff line
@@ -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);

drivers/pci/probe.c

+21 −0
Original line number Diff line number Diff line
@@ -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;

include/linux/pci.h

+23 −0
Original line number Diff line number Diff line
@@ -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>