x86/amd_node: Fix PCI device reference counting in amd_smn_init()grafted

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 <sashiko-bot@kernel.org>
Assisted-by: LLM
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com

1 files changed, 156 insertions, 0 deletions

diff --git a/Documentation/gpu/amdgpu/driver-misc.rst b/Documentation/gpu/amdgpu/driver-misc.rst
new file mode 100644
index 000000000..e1a964c3a
--- /dev/null
+++ b/Documentation/gpu/amdgpu/driver-misc.rst
@@ -0,0 +1,156 @@
+================================
+ Misc AMDGPU driver information
+================================
+
+GPU Product Information
+=======================
+
+Information about the GPU can be obtained on certain cards
+via sysfs
+
+product_name
+------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_fru_eeprom.c
+   :doc: product_name
+
+product_number
+--------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_fru_eeprom.c
+   :doc: product_number
+
+serial_number
+-------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_fru_eeprom.c
+   :doc: serial_number
+
+fru_id
+-------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_fru_eeprom.c
+   :doc: fru_id
+
+manufacturer
+-------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_fru_eeprom.c
+   :doc: manufacturer
+
+unique_id
+---------
+
+.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c
+   :doc: unique_id
+
+board_info
+----------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+   :doc: board_info
+
+GPU Memory Usage Information
+============================
+
+Various memory accounting can be accessed via sysfs
+
+mem_info_vram_total
+-------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+   :doc: mem_info_vram_total
+
+mem_info_vram_used
+------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+   :doc: mem_info_vram_used
+
+mem_info_vis_vram_total
+-----------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+   :doc: mem_info_vis_vram_total
+
+mem_info_vis_vram_used
+----------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+   :doc: mem_info_vis_vram_used
+
+mem_info_gtt_total
+------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
+   :doc: mem_info_gtt_total
+
+mem_info_gtt_used
+-----------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
+   :doc: mem_info_gtt_used
+
+PCIe Accounting Information
+===========================
+
+pcie_bw
+-------
+
+.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c
+   :doc: pcie_bw
+
+pcie_replay_count
+-----------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+   :doc: pcie_replay_count
+
+GPU SmartShift Information
+==========================
+
+GPU SmartShift information via sysfs
+
+smartshift_apu_power
+--------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c
+   :doc: smartshift_apu_power
+
+smartshift_dgpu_power
+---------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c
+   :doc: smartshift_dgpu_power
+
+smartshift_bias
+---------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c
+   :doc: smartshift_bias
+
+UMA Carveout
+============
+
+Some versions of Atom ROM expose available options for the VRAM carveout sizes,
+and allow changes to the carveout size via the ATCS function code 0xA on supported
+BIOS implementations.
+
+For those platforms, users can use the following files under uma/ to set the
+carveout size, in a way similar to what Windows users can do in the "Tuning"
+tab in AMD Adrenalin.
+
+Note that for BIOS implementations that don't support this, these files will not
+be created at all.
+
+uma/carveout_options
+--------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+   :doc: uma/carveout_options
+
+uma/carveout
+--------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+   :doc: uma/carveout