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authorJoel Fernandes <joelagnelf@nvidia.com>2026-07-18 13:15:36 -0400
committerPaul E. McKenney <paulmck@kernel.org>2026-07-23 10:39:57 -0700
commit34ff636f322c6d5e4f0a52338fa63a7dff09a495 (patch)
tree7629759c1ec7148b95bc8ab3080df20a5ecd2273 /Documentation/usb/chipidea.rst
downloadlinux-stable-34ff636f322c6d5e4f0a52338fa63a7dff09a495.tar.gz
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scftorture: Count single_rpc offline failures in statistics outputgrafted
scf_torture_stats_print() aggregates each invoker thread's counters into a local scf_statistics structure before printing, but the n_single_rpc_ofl field is missing from the aggregation loop. As a result, the "single_rpc_ofl" value printed in the statistics line is always zero, even when smp_call_function_single() invocations for the RPC test have failed due to offline CPUs and been counted by the invoker threads. Add the missing accumulation so that the printed value reflects the actual counts. Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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+==============================================
+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;