From 27600805e62f800bacf990354632eae4e487d34c Mon Sep 17 00:00:00 2001 From: Yazen Ghannam Date: Thu, 3 Sep 2026 10:43:25 -0500 Subject: x86/amd_node: Fix PCI device reference counting in amd_smn_init() The local "root" pointer is a temporary variable used during the device search. Therefore, refcount related to the search iterators should be cleaned up after the search is complete. Use the __free() cleanup macro to ensure the refcount is decremented when the temporary pointer goes out of scope. Additionally, increment the refcount when caching a root pointer. This ensures the in-use refcount is separate from the temporary search refcounting. Finally, drop the redundant "root = NULL" before the second search loop. The pci_get_class() iterator always decrements the refcount of its "from" argument, so the first loop can only fall through with "root" already NULL. Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching") Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com Reported-by: Sashiko Assisted-by: LLM Signed-off-by: Yazen Ghannam Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Mario Limonciello (AMD) Cc: Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com --- Documentation/gpu/amdgpu/ptl.rst | 94 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 94 insertions(+) create mode 100644 Documentation/gpu/amdgpu/ptl.rst (limited to 'Documentation/gpu/amdgpu/ptl.rst') diff --git a/Documentation/gpu/amdgpu/ptl.rst b/Documentation/gpu/amdgpu/ptl.rst new file mode 100644 index 000000000..c7f16dea7 --- /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`. -- cgit v1.3.1