AMD Sensor Fusion Hub
=====================
-AMD Sensor Fusion Hub (SFH) is part of an SOC starting from Ryzen based platforms.
+AMD Sensor Fusion Hub (SFH) is part of an SOC starting from Ryzen-based platforms.
The solution is working well on several OEM products. AMD SFH uses HID over PCIe bus.
In terms of architecture it resembles ISH, however the major difference is all
the HID reports are generated as part of the kernel driver.
-1. Block Diagram
-================
+Block Diagram
+-------------
::
AMD HID Transport Layer
-----------------------
AMD SFH transport is also implemented as a bus. Each client application executing in the AMD MP2 is
-registered as a device on this bus. Here: MP2 which is an ARM core connected to x86 for processing
+registered as a device on this bus. Here, MP2 is an ARM core connected to x86 for processing
sensor data. The layer, which binds each device (AMD SFH HID driver) identifies the device type and
-registers with the hid core. Transport layer attach a constant "struct hid_ll_driver" object with
+registers with the HID core. Transport layer attaches a constant "struct hid_ll_driver" object with
each device. Once a device is registered with HID core, the callbacks provided via this struct are
used by HID core to communicate with the device. AMD HID Transport layer implements the synchronous calls.
AMD HID Client Layer
--------------------
-This layer is responsible to implement HID request and descriptors. As firmware is OS agnostic, HID
+This layer is responsible to implement HID requests and descriptors. As firmware is OS agnostic, HID
client layer fills the HID request structure and descriptors. HID client layer is complex as it is
-interface between MP2 PCIe layer and HID. HID client layer initialized the MP2 PCIe layer and holds
-the instance of MP2 layer. It identifies the number of sensors connected using MP2-PCIe layer. Base
-on that allocates the DRAM address for each and every sensor and pass it to MP2-PCIe driver.On
-enumeration of each the sensor, client layer fills the HID Descriptor structure and HID input repor
+interface between MP2 PCIe layer and HID. HID client layer initializes the MP2 PCIe layer and holds
+the instance of MP2 layer. It identifies the number of sensors connected using MP2-PCIe layer. Based
+on that allocates the DRAM address for each and every sensor and passes it to MP2-PCIe driver. On
+enumeration of each sensor, client layer fills the HID Descriptor structure and HID input report
structure. HID Feature report structure is optional. The report descriptor structure varies from
sensor to sensor.
2. Data transfer via DRAM.
3. Supported sensor info via P2C registers.
-Commands are sent to MP2 using C2P Mailbox registers. Writing into C2P Message registers generate
+Commands are sent to MP2 using C2P Mailbox registers. Writing into C2P Message registers generates
interrupt to MP2. The client layer allocates the physical memory and the same is sent to MP2 via
the PCI layer. MP2 firmware writes the command output to the access DRAM memory which the client
layer has allocated. Firmware always writes minimum of 32 bytes into DRAM. So as a protocol driver