docs(adapter): document device and vendor IDs repr. (#3763)

CHANGELOG.md

@@ -51,6 +51,7 @@ Bottom level categories:
 #### General
 
 - Document feature requirements for `DEPTH32FLOAT_STENCIL8` by @ErichDonGubler in [#3734](https://github.com/gfx-rs/wgpu/pull/3734).
+- Flesh out docs. for `AdapterInfo::{device,vendor}` by @ErichDonGubler in [#3763](https://github.com/gfx-rs/wgpu/pull/3763). 
 
 ### Bug Fixes
 

wgpu-types/src/lib.rs

@@ -1303,12 +1303,28 @@ pub enum DeviceType {
 pub struct AdapterInfo {
     /// Adapter name
     pub name: String,
-    /// Vendor PCI id of the adapter
+    /// [`Backend`]-specific vendor ID of the adapter
     ///
-    /// If the vendor has no PCI id, then this value will be the backend's vendor id equivalent. On Vulkan,
-    /// Mesa would have a vendor id equivalent to it's `VkVendorId` value.
+    /// This generally is a 16-bit PCI vendor ID in the least significant bytes of this field.
+    /// However, more significant bytes may be non-zero if the backend uses a different
+    /// representation.
+    ///
+    /// * For [`Backend::Vulkan`], the [`VkPhysicalDeviceProperties::vendorID`] is used, which is
+    ///     a superset of PCI IDs.
+    ///
+    /// [`VkPhysicalDeviceProperties::vendorID`]: https://registry.khronos.org/vulkan/specs/1.3-extensions/man/html/VkPhysicalDeviceProperties.html
     pub vendor: u32,
-    /// PCI id of the adapter
+    /// [`Backend`]-specific device ID of the adapter
+    ///
+    ///
+    /// This generally is a 16-bit PCI device ID in the least significant bytes of this field.
+    /// However, more significant bytes may be non-zero if the backend uses a different
+    /// representation.
+    ///
+    /// * For [`Backend::Vulkan`], the [`VkPhysicalDeviceProperties::deviceID`] is used, which is
+    ///    a superset of PCI IDs.
+    ///
+    /// [`VkPhysicalDeviceProperties::deviceID`]: https://registry.khronos.org/vulkan/specs/1.3-extensions/man/html/VkPhysicalDeviceProperties.html
     pub device: u32,
     /// Type of device
     pub device_type: DeviceType,