On Mon, Oct 28, 2024 at 04:09:30PM +0100, Bart Van Severen wrote: > On Fri, Oct 25, 2024 at 9:37 PM Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > > > > On Thu, Oct 24, 2024 at 11:37:50AM +0200, Bart Van Severen wrote: > > > Hi, > > > > > > We have a use case to remote control a pc through a composite gadget > > > consisting of keyboard, mouse and tablet functions. > > > The problem we face is that when the pc is sent to sleep, we cannot > > > wake it by writing to the hid device, which is what you > > > would expect to work. > > > > > > We're running on Xilinx Zynqmp soc/DWC3 290A. > > > > > > We have set the bmAttributes ch9 USB_CONFIG_ATT_WAKEUP bit and do see > > > the set_feature request to enable remote > > > wakeup, just before the pc goes to sleep. > > > > Do you see a wakeup request from the gadget to the host? > > No, I don't see any wakeup request towards the host. As one would expect, given that there was no call to usb_gadget_wakeup(). > > > We noticed the recent relevant work > > > https://lore.kernel.org/linux-usb/1679694482-16430-1-git-send-email-quic_eserrao@xxxxxxxxxxx/, > > > regarding function suspend/resume and remote wakeup improvements. > > > > > > However, the main question we have is: what would be the right place > > > in the gadget framework to fix the issue where a hid write > > > doesn't trigger a remote wake up when the usb device is suspended and > > > the host has enabled remote wakeup. > > > > Probably the drivers/usb/gadget/function/f_hid.c file. I don't know > > anything about how this gadget driver works, but the file doesn't have > > any calls to usb_gadget_wakeup(), which means it won't generate a wakeup > > request no matter what you write to it. > > > > Alan Stern > > > > That's what my initial thought was also, and that certainly works. > But then I wondered if it isn't a better idea to handle this further down, to > avoid having to write similar code in all function drivers, say in the > gadget core? The gadget core doesn't know when the user wants to issue a wakeup request; only the function driver knows this. (For instance, only f_hid.c knows when there has been an hid write.) And the whole point of usb_gadget_wakeup() is that it provides a way for the function drivers to tell the gadget core to issue a wakeup request. Alan Stern
