On Fri, Mar 10, 2017 at 2:23 PM, Lukas Wunner <lukas@xxxxxxxxx> wrote:
> +/**
> + * 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.)
The "soldered to the mainboard" comment is misleading. We'll reach
the host bridge and return "false" for any non-Thunderbolt-attached
device, including all plug-in PCI and PCIe devices.
> + */
> +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>
>
> --
> 2.11.0
>
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