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/usb/chipidea.rst | 134 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 134 insertions(+) create mode 100644 Documentation/usb/chipidea.rst (limited to 'Documentation/usb/chipidea.rst') 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; -- cgit v1.3.1