在 2020/5/9 上午12:29, Bryan O'Donoghue 写道:
Right now we don't report to user-space a role switch when doing a usb_role_switch_set_role() despite having registered the uevent callbacks. This patch switches on the notifications allowing user-space to see role-switch change notifications and subsequently determine the current controller data-role. example: PFX=/devices/platform/soc/78d9000.usb/ci_hdrc.0 root@somebox# udevadm monitor -p KERNEL[49.894994] change $PFX/usb_role/ci_hdrc.0-role-switch (usb_role) ACTION=change DEVPATH=$PFX/usb_role/ci_hdrc.0-role-switch SUBSYSTEM=usb_role DEVTYPE=usb_role_switch USB_ROLE_SWITCH=ci_hdrc.0-role-switch SEQNUM=2432 Cc: Heikki Krogerus <heikki.kroge...@linux.intel.com> Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org> Cc: Chunfeng Yun <chunfeng....@mediatek.com> Cc: Suzuki K Poulose <suzuki.poul...@arm.com> Cc: Alexandre Belloni <alexandre.bell...@bootlin.com> Cc: Wen Yang <weny...@linux.alibaba.com> Cc: chenqiwu <chenq...@xiaomi.com> Cc: linux-kernel@vger.kernel.org Signed-off-by: Bryan O'Donoghue <bryan.odonog...@linaro.org> --- drivers/usb/roles/class.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/usb/roles/class.c b/drivers/usb/roles/class.c index 5b17709821df..27d92af29635 100644 --- a/drivers/usb/roles/class.c +++ b/drivers/usb/roles/class.c @@ -49,8 +49,10 @@ int usb_role_switch_set_role(struct usb_role_switch *sw, enum usb_role role) mutex_lock(&sw->lock);ret = sw->set(sw, role);- if (!ret) + if (!ret) { sw->role = role; + kobject_uevent(&sw->dev.kobj, KOBJ_CHANGE); + }mutex_unlock(&sw->lock);
Hi, we may also need to deal with the return value of kobject_uevent(). Should we move it under the line mutex_unlock(&sw->lock)?
Regards, Wen
