The PTL (Peak Tops Limiter) feature exposes per-GPU sysfs files under /sys/class/drm/cardX/device/ptl/ to allow users to enable or disable PTL, configure preferred data formats, and query supported formats. The usage of these sysfs files is not always obvious, so add documentation to describe their purpose and provide concrete usage examples.
V3 changes: * format show will display preferred formats instead of N/A (Alex) Signed-off-by: Perry Yuan <[email protected]> Suggested-by: Alex Deucher <[email protected]> Reviewed-by: Yifan Zhang <[email protected]> --- Documentation/gpu/amdgpu/index.rst | 1 + Documentation/gpu/amdgpu/ptl.rst | 94 ++++++++++++++++++++++++++++++ 2 files changed, 95 insertions(+) create mode 100644 Documentation/gpu/amdgpu/ptl.rst diff --git a/Documentation/gpu/amdgpu/index.rst b/Documentation/gpu/amdgpu/index.rst index 8732084186a4..b2ab182236ef 100644 --- a/Documentation/gpu/amdgpu/index.rst +++ b/Documentation/gpu/amdgpu/index.rst @@ -23,3 +23,4 @@ Next (GCN), Radeon DNA (RDNA), and Compute DNA (CDNA) architectures. debugfs process-isolation amdgpu-glossary + ptl diff --git a/Documentation/gpu/amdgpu/ptl.rst b/Documentation/gpu/amdgpu/ptl.rst new file mode 100644 index 000000000000..c7f16dea7954 --- /dev/null +++ b/Documentation/gpu/amdgpu/ptl.rst @@ -0,0 +1,94 @@ +======================================= +Peak Tops Limiter (PTL) sysfs Interface +======================================= + +Overview +-------- +The Peak Tops Limiter (PTL) sysfs interface enables users to control and +configure the PTL feature for each GPU individually. All PTL-related +sysfs files are located under `/sys/class/drm/cardX/device/ptl/`, where +`X` is the GPU index. Through these files, users can enable or disable +PTL, set preferred data formats, and query supported formats for each GPU. + +PTL sysfs files +---------------- +The following files are available under `/sys/class/drm/cardX/device/ptl/`: + +- `ptl_enable` +- `ptl_format` +- `ptl_supported_formats` + +PTL Enable/Disable +------------------ +File: `ptl_enable` +Type: Read/Write (rw) + +Read: Returns the current PTL status as a string: `enabled` if PTL +is active, or `disabled` if inactive. + +Write: + +- Write `1` or `enabled` to enable PTL +- Write `0` or `disabled` to disable PTL + +Examples:: + + # Query PTL status + cat /sys/class/drm/card1/device/ptl/ptl_enable + # Output: enabled + + # Enable PTL + sudo bash -c "echo 1 > /sys/class/drm/card1/device/ptl/ptl_enable" + + # Disable PTL + sudo bash -c "echo 0 > /sys/class/drm/card1/device/ptl/ptl_enable" + +PTL Format (Preferred Data Formats) +----------------------------------- +File: `ptl_format` +Type: Read/Write (rw) + +Read: Returns the two preferred formats, e.g. `I8,F32`. + +Write: Accepts two formats separated by a comma, e.g. `I8,F32`. + +- Both formats must be supported and different. +- If an invalid format is provided (not supported, or both formats are the + same), the driver will return "write error: Invalid argument". + +Examples:: + + # Query PTL formats + cat /sys/class/drm/card1/device/ptl/ptl_format + # Output: I8,F32 + + # Set PTL formats + sudo bash -c "echo I8,F32 > /sys/class/drm/card1/device/ptl/ptl_format" + +Supported Formats +----------------- +File: `ptl_supported_formats` +Type: Read-only (r) + +Read: Returns a comma-separated list of supported formats, e.g. +`I8,F16,BF16,F32,F64`. + +Example:: + + # Check supported formats + cat /sys/class/drm/card1/device/ptl/ptl_supported_formats + # Output: I8,F16,BF16,F32,F64 + +Behavioral Notes +---------------- +- PTL formats can only be set when PTL is enabled. +- If PTL is disabled, `ptl_format` returns `N/A`. +- Only two formats can be set at a time, and they must be from the supported set and different.. +- All commands support per-GPU targeting. +- Root permission is required to enable/disable PTL or change formats. +- If the hardware does not support PTL, the PTL sysfs directory will not + be created. + +Implementation +-------------- +The PTL sysfs nodes are implemented in `drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c`. -- 2.34.1
