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, 134 insertions, 0 deletions

diff --git a/Documentation/usb/chipidea.rst b/Documentation/usb/chipidea.rst
new file mode 100644
index 000000000..d9920c24e
--- /dev/null
+++ b/Documentation/usb/chipidea.rst
@@ -0,0 +1,134 @@
+==============================================
+ChipIdea Highspeed Dual Role Controller Driver
+==============================================
+
+1. How to test OTG FSM(HNP and SRP)
+-----------------------------------
+
+To show how to demo OTG HNP and SRP functions via sys input files
+with 2 Freescale i.MX6Q sabre SD boards.
+
+1.1 How to enable OTG FSM
+-------------------------
+
+1.1.1 Select CONFIG_USB_OTG_FSM in menuconfig, rebuild kernel
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Image and modules. If you want to check some internal
+variables for otg fsm, mount debugfs, there are 2 files
+which can show otg fsm variables and some controller registers value::
+
+	cat /sys/kernel/debug/ci_hdrc.0/otg
+	cat /sys/kernel/debug/ci_hdrc.0/registers
+
+1.1.2 Add below entries in your dts file for your controller node
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+::
+
+	otg-rev = <0x0200>;
+	adp-disable;
+
+1.2 Test operations
+-------------------
+
+1) Power up 2 Freescale i.MX6Q sabre SD boards with gadget class driver loaded
+   (e.g. g_mass_storage).
+
+2) Connect 2 boards with usb cable: one end is micro A plug, the other end
+   is micro B plug.
+
+   The A-device (with micro A plug inserted) should enumerate B-device.
+
+3) Role switch
+
+   On B-device::
+
+	echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
+
+   B-device should take host role and enumerate A-device.
+
+4) A-device switch back to host.
+
+   On B-device::
+
+	echo 0 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
+
+   or, by introducing HNP polling, B-Host can know when A-peripheral wishes to
+   be in the host role, so this role switch also can be triggered in
+   A-peripheral side by answering the polling from B-Host. This can be done on
+   A-device::
+
+	echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_req
+
+   A-device should switch back to host and enumerate B-device.
+
+5) Remove B-device (unplug micro B plug) and insert again in 10 seconds;
+   A-device should enumerate B-device again.
+
+6) Remove B-device (unplug micro B plug) and insert again after 10 seconds;
+   A-device should NOT enumerate B-device.
+
+   if A-device wants to use bus:
+
+   On A-device::
+
+	echo 0 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_drop
+	echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_req
+
+   if B-device wants to use bus:
+
+   On B-device::
+
+	echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
+
+7) A-device power down the bus.
+
+   On A-device::
+
+	echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_drop
+
+   A-device should disconnect with B-device and power down the bus.
+
+8) B-device does data pulse for SRP.
+
+   On B-device::
+
+	echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
+
+   A-device should resume usb bus and enumerate B-device.
+
+1.3 Reference document
+----------------------
+"On-The-Go and Embedded Host Supplement to the USB Revision 2.0 Specification
+July 27, 2012 Revision 2.0 version 1.1a"
+
+2. How to enable USB as system wakeup source
+--------------------------------------------
+Below is the example for how to enable USB as system wakeup source
+on an imx6 platform.
+
+2.1 Enable core's wakeup::
+
+	echo enabled > /sys/bus/platform/devices/ci_hdrc.0/power/wakeup
+
+2.2 Enable glue layer's wakeup::
+
+	echo enabled > /sys/bus/platform/devices/2184000.usb/power/wakeup
+
+2.3 Enable PHY's wakeup (optional)::
+
+	echo enabled > /sys/bus/platform/devices/20c9000.usbphy/power/wakeup
+
+2.4 Enable roothub's wakeup::
+
+	echo enabled > /sys/bus/usb/devices/usb1/power/wakeup
+
+2.5 Enable related device's wakeup::
+
+	echo enabled > /sys/bus/usb/devices/1-1/power/wakeup
+
+If the system has only one usb port, and you want usb wakeup at this port, you
+can use the below script to enable usb wakeup::
+
+	for i in $(find /sys -name wakeup | grep usb);do echo enabled > $i;done;