xref: /linux/Documentation/gpu/amdgpu/gc/index.rst (revision ab93e0dd72c37d378dd936f031ffb83ff2bd87ce)

.. _amdgpu-gc:

========================================
 drm/amdgpu - Graphics and Compute (GC)
========================================

The relationship between the CPU and GPU can be described as the
producer-consumer problem, where the CPU fills out a buffer with operations
(producer) to be executed by the GPU (consumer). The requested operations in
the buffer are called Command Packets, which can be summarized as a compressed
way of transmitting command information to the graphics controller.

The component that acts as the front end between the CPU and the GPU is called
the Command Processor (CP). This component is responsible for providing greater
flexibility to the GC since CP makes it possible to program various aspects of
the GPU pipeline. CP also coordinates the communication between the CPU and GPU
via a mechanism named **Ring Buffers**, where the CPU appends information to
the buffer while the GPU removes operations. It is relevant to highlight that a
CPU can add a pointer to the Ring Buffer that points to another region of
memory outside the Ring Buffer, and CP can handle it; this mechanism is called
**Indirect Buffer (IB)**. CP receives and parses the Command Streams (CS), and
writes the operations to the correct hardware blocks.

Graphics (GFX) and Compute Microcontrollers
-------------------------------------------

GC is a large block, and as a result, it has multiple firmware associated with
it. Some of them are:

CP (Command Processor)
    The name for the hardware block that encompasses the front end of the
    GFX/Compute pipeline. Consists mainly of a bunch of microcontrollers
    (PFP, ME, CE, MEC). The firmware that runs on these microcontrollers
    provides the driver interface to interact with the GFX/Compute engine.

    MEC (MicroEngine Compute)
        This is the microcontroller that controls the compute queues on the
        GFX/compute engine.

    MES (MicroEngine Scheduler)
        This is the engine for managing queues. For more details check
        :ref:`MicroEngine Scheduler (MES) <amdgpu-mes>`.

RLC (RunList Controller)
    This is another microcontroller in the GFX/Compute engine. It handles
    power management related functionality within the GFX/Compute engine.
    The name is a vestige of old hardware where it was originally added
    and doesn't really have much relation to what the engine does now.

.. toctree::

   mes.rst