1======================================= 2Peak Tops Limiter (PTL) sysfs Interface 3======================================= 4 5Overview 6-------- 7The Peak Tops Limiter (PTL) sysfs interface enables users to control and 8configure the PTL feature for each GPU individually. All PTL-related 9sysfs files are located under `/sys/class/drm/cardX/device/ptl/`, where 10`X` is the GPU index. Through these files, users can enable or disable 11PTL, set preferred data formats, and query supported formats for each GPU. 12 13PTL sysfs files 14---------------- 15The following files are available under `/sys/class/drm/cardX/device/ptl/`: 16 17- `ptl_enable` 18- `ptl_format` 19- `ptl_supported_formats` 20 21PTL Enable/Disable 22------------------ 23File: `ptl_enable` 24Type: Read/Write (rw) 25 26Read: Returns the current PTL status as a string: `enabled` if PTL 27is active, or `disabled` if inactive. 28 29Write: 30 31- Write `1` or `enabled` to enable PTL 32- Write `0` or `disabled` to disable PTL 33 34Examples:: 35 36 # Query PTL status 37 cat /sys/class/drm/card1/device/ptl/ptl_enable 38 # Output: enabled 39 40 # Enable PTL 41 sudo bash -c "echo 1 > /sys/class/drm/card1/device/ptl/ptl_enable" 42 43 # Disable PTL 44 sudo bash -c "echo 0 > /sys/class/drm/card1/device/ptl/ptl_enable" 45 46PTL Format (Preferred Data Formats) 47----------------------------------- 48File: `ptl_format` 49Type: Read/Write (rw) 50 51Read: Returns the two preferred formats, e.g. `I8,F32`. 52 53Write: Accepts two formats separated by a comma, e.g. `I8,F32`. 54 55- Both formats must be supported and different. 56- If an invalid format is provided (not supported, or both formats are the 57 same), the driver will return "write error: Invalid argument". 58 59Examples:: 60 61 # Query PTL formats 62 cat /sys/class/drm/card1/device/ptl/ptl_format 63 # Output: I8,F32 64 65 # Set PTL formats 66 sudo bash -c "echo I8,F32 > /sys/class/drm/card1/device/ptl/ptl_format" 67 68Supported Formats 69----------------- 70File: `ptl_supported_formats` 71Type: Read-only (r) 72 73Read: Returns a comma-separated list of supported formats, e.g. 74`I8,F16,BF16,F32,F64`. 75 76Example:: 77 78 # Check supported formats 79 cat /sys/class/drm/card1/device/ptl/ptl_supported_formats 80 # Output: I8,F16,BF16,F32,F64 81 82Behavioral Notes 83---------------- 84- PTL formats can only be set when PTL is enabled. 85- If PTL is disabled, `ptl_format` returns `N/A`. 86- Only two formats can be set at a time, and they must be from the supported set and different.. 87- All commands support per-GPU targeting. 88- Root permission is required to enable/disable PTL or change formats. 89- If the hardware does not support PTL, the PTL sysfs directory will not 90 be created. 91 92Implementation 93-------------- 94The PTL sysfs nodes are implemented in `drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c`. 95