Hi, John Stultz <john.stultz@xxxxxxxxxx> writes: > Hey all, > I wanted to send these out for comment and thoughts. > > Since ~4.20, when the functionfs gadget enabled scatter-gather > support, we have seen problems with adb connections stalling and > stopping to function on hardware with dwc3 usb controllers. > Specifically, HiKey960, Dragonboard 845c, and Pixel3 devices. > > Initally the workaround we used was to simply disable scatter > gather support on the dwc3 by commenting out the > "dwc->gadget.sg_supported = true;" line. > > After working with Fei Yang, who was seeing similar trouble on > Intel dwc3 based hardare, Thinh Nguyen mentioned that a fix had > already been found and pointed me to one of Anurag's patches. > > This solved the issue on HiKey960 and I sent it out to the list > but didn't get any feedback. > > Additional testing with the Dragonboard 845c found that that > first fix was not sufficient, and so I've sat on the fix > thinking something deeper was amiss and went back to the hack > of disabling sg_supported on all dwc3 platforms. > > In the following months Fei's continued and repeated efforts > didn't seem to get enough review to result in a fix, and they've > since moved on to other work. > > Recently, I found that folks at qcom have seen similer issues > and pointed me to the second patch in this series, which does > seem to resolve the issue on the Dragonboard 845c, but not the > HiKey960 on its own. > > So I wanted to send these patches out for comment. There's > clearly a number of folks seeing broken behavior for ahwile on > dwc3 hardware, and we're all seeemingly working around it in our > own ways, so either those individual fixes need to get upstream > or we need to figure out some deeper solution to the issue. > > So I wanted to send these two out for review and feedback. > > thanks > -john > > Cc: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx> > Cc: Yang Fei <fei.yang@xxxxxxxxx> > Cc: Thinh Nguyen <thinhn@xxxxxxxxxxxx> > Cc: Tejas Joglekar <tejas.joglekar@xxxxxxxxxxxx> > Cc: Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxxxx> > Cc: Jack Pham <jackp@xxxxxxxxxxxxxx> > Cc: Todd Kjos <tkjos@xxxxxxxxxx> > Cc: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> > Cc: Linux USB List <linux-usb@xxxxxxxxxxxxxxx> > Cc: stable <stable@xxxxxxxxxxxxxxx> > > Anurag Kumar Vulisha (2): > usb: dwc3: gadget: Check for IOC/LST bit in both event->status and > TRB->ctrl fields > usb: dwc3: gadget: Correct the logic for finding last SG entry I remember commenting on these patches before and never getting a newer version from Anurag. -- balbi
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