On Wed, Oct 28, 2020 at 03:57:03PM +0200, Felipe Balbi wrote: > > Hi, > > Dejin Zheng <zhengdejin5@xxxxxxxxx> writes: > >> Dejin Zheng <zhengdejin5@xxxxxxxxx> writes: > >> > According to Synopsys Programming Guide chapter 2.2 Register Resets, > >> > it cannot reset the DCTL register by setting DCTL.CSFTRST for core soft > >> > reset, if DWC3 controller as a slave device and stay connected with a usb > >> > host, then, while rebooting linux, it will fail to reinitialize dwc3 as a > >> > slave device when the DWC3 controller did not power off. because the > >> > connection status is incorrect, so we also need to clear DCTL.RUN_STOP > >> > bit for disabling connect when doing core soft reset. There will still > >> > be other stale configuration in DCTL, so reset the other fields of DCTL > >> > to the default value 0. > >> > >> This commit log is a bit hard to understand. When does this problem > >> actually happen? It seems like it's in the case of, perhaps, kexecing > >> into a new kernel, is that right? > >> > > It happens when entering the kernel for the second time after the reboot > > command. > > > >> At the time dwc3_core_soft_reset() is called, the assumption is that > >> we're starting with a clean core, from power up. If we have stale > >> configuration from a previous run, we should fix this on the exit > >> path. Note that if we're reaching probe with pull up connected, we > >> already have issues elsewhere. > >> > >> I think this is not the right fix for the problem. > >> > > I think you are right, Thinh also suggested me fix it on the exit path > > in the previous patch v2. Do you think I can do these cleanups in the > > shutdown hook of this driver? Balbi, is there a more suitable place to > > do this by your rich experience? Thanks! > > I don't think shutdown is called during removal, I'm not sure. I think > we had some fixes done in shutdown time, though. Test it out, but make > sure there are no issues with a regular modprobe cycle. > Balbi, thanks for your suggestions, I will do a test in the shutdown hook first. > -- > balbi
