[PATCH v2 2/3] Documentation/gpu: include description of AMDGPU hardware structure
Yann Dirson
ydirson at free.fr
Fri Dec 10 18:20:29 UTC 2021
This is Alex' description from the "gpu block diagram" thread, edited to
fit as ReST.
Originally-by: Alex Deucher <alexander.deucher at amd.com>
Signed-off-by: Yann Dirson <ydirson at free.fr>
Acked-by: Harry Wentland <harry.wentland at amd.com>
---
Documentation/gpu/amdgpu/driver-core.rst | 81 ++++++++++++++++++++++++
1 file changed, 81 insertions(+)
diff --git a/Documentation/gpu/amdgpu/driver-core.rst b/Documentation/gpu/amdgpu/driver-core.rst
index 97f9a9b68924..b870a63c64dd 100644
--- a/Documentation/gpu/amdgpu/driver-core.rst
+++ b/Documentation/gpu/amdgpu/driver-core.rst
@@ -2,6 +2,87 @@
Core Driver Infrastructure
============================
+GPU hardware structure
+======================
+
+Each ASIC is a collection of hardware blocks. We refer to them as
+"IPs" (Intellectual Property blocks). Each IP encapsulates certain
+functionality. IPs are versioned and can also be mixed and matched.
+E.g., you might have two different ASICs that both have SDMA 5.x IPs.
+The driver is arranged by IPs. There are driver components to handle
+the initialization and operation of each IP. There are also a bunch
+of smaller IPs that don't really need much if any driver interaction.
+Those end up getting lumped into the common stuff in the soc files.
+The soc files (e.g., vi.c, soc15.c nv.c) contain code for aspects of
+the SoC itself rather than specific IPs. E.g., things like GPU resets
+and register access functions are SoC dependent.
+
+An APU contains more than just CPU and GPU, it also contains all of
+the platform stuff (audio, usb, gpio, etc.). Also, a lot of
+components are shared between the CPU, platform, and the GPU (e.g.,
+SMU, PSP, etc.). Specific components (CPU, GPU, etc.) usually have
+their interface to interact with those common components. For things
+like S0i3 there is a ton of coordination required across all the
+components, but that is probably a bit beyond the scope of this
+section.
+
+With respect to the GPU, we have the following major IPs:
+
+GMC (Graphics Memory Controller)
+ This was a dedicated IP on older pre-vega chips, but has since
+ become somewhat decentralized on vega and newer chips. They now
+ have dedicated memory hubs for specific IPs or groups of IPs. We
+ still treat it as a single component in the driver however since
+ the programming model is still pretty similar. This is how the
+ different IPs on the GPU get the memory (VRAM or system memory).
+ It also provides the support for per process GPU virtual address
+ spaces.
+
+IH (Interrupt Handler)
+ This is the interrupt controller on the GPU. All of the IPs feed
+ their interrupts into this IP and it aggregates them into a set of
+ ring buffers that the driver can parse to handle interrupts from
+ different IPs.
+
+PSP (Platform Security Processor)
+ This handles security policy for the SoC and executes trusted
+ applications, and validates and loads firmwares for other blocks.
+
+SMU (System Management Unit)
+ This is the power management microcontroller. It manages the entire
+ SoC. The driver interacts with it to control power management
+ features like clocks, voltages, power rails, etc.
+
+DCN (Display Controller Next)
+ This is the display controller. It handles the display hardware.
+
+SDMA (System DMA)
+ This is a multi-purpose DMA engine. The kernel driver uses it for
+ various things including paging and GPU page table updates. It's also
+ exposed to userspace for use by user mode drivers (OpenGL, Vulkan,
+ etc.)
+
+GC (Graphics and Compute)
+ This is the graphics and compute engine, i.e., the block that
+ encompasses the 3D pipeline and and shader blocks. This is by far the
+ largest block on the GPU. The 3D pipeline has tons of sub-blocks. In
+ addition to that, it also contains the CP microcontrollers (ME, PFP,
+ CE, MEC) and the RLC microcontroller. It's exposed to userspace for
+ user mode drivers (OpenGL, Vulkan, OpenCL, etc.)
+
+VCN (Video Core Next)
+ This is the multi-media engine. It handles video and image encode and
+ decode. It's exposed to userspace for user mode drivers (VA-API,
+ OpenMAX, etc.)
+
+Driver structure
+================
+
+In general, the driver has a list of all of the IPs on a particular
+SoC and for things like init/fini/suspend/resume, more or less just
+walks the list and handles each IP.
+
+
.. _amdgpu_memory_domains:
Memory Domains
--
2.31.1
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