On Fri, Dec 31, 2021 at 07:59:31PM +0800, Yaqin Pan wrote: > On Thu, 30 Dec 2021 16:48:09 +0100 Greg Kroah-Hartman wrote: > >On Thu, Dec 30, 2021 at 11:36:12PM +0800, Yaqin Pan wrote: > >> On Thu, 30 Dec 2021 15:12:27 +0100 Greg Kroah-Hartman wrote: > >> >> This quirk is only for dwc3 host mode. > >> >> the dwc3 controller can't emurate some devices successfully. > >> >> For example, TF card reader (aaaa:8816): > >> >> failed log > >> >> usb 1-1: new high-speed USB device number 2 using xhci-hcd > >> >> usb 1-1: device descriptor read/all, error -110 > >> >> >From the usb analyzer, always return NAK in the data phase. > >> >> if enable the GUCTL.SPRSCTRLTRANSEN bit. then the log is: > >> >> usb 2-1: new high-speed USB device number 3 using xhci-hcd > >> >> usb 2-1: New USB device found, idVendor=aaaa, > >> >> idProduct=8816, bcdDevice=13.08 > >> >> usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3 > >> >> usb 2-1: Product: MXT USB Device > >> >> usb 2-1: Manufacturer: MXTronics > >> >> usb 2-1: SerialNumber: 150101v01 > >> >> usb 2-1: New USB device found, VID=aaaa, PID=8816 > >> >> > >> >> Some devices are slow in responding to Control transfers. > >> >> Scheduling mulitiple transactions in one microframe/frame > >> >> can cause the devices to misbehave. if this qurik is enabled, > >> >> the host controller schedules transations for a Control transfer > >> >> in defferent microframes/frame. > >> > > >> >If this is needed for all devices (i.e. you do not know what device is > >> >going to be plugged in), why not just enable it for all controllers? > >> >Why whould you NOT want this enabled? > >> > > >> >Or is this a broken hardware device and only specific host controllers > >> >need this? If so, how do we know which ones need this set and which do > >> >not? > >> > >> I think not all dwc3 controllers need this. For cell phone,customers may > >> use various usb devices, we can enable this quirk to fix some compatibility > >> issues. For some chip platform of qcom, i encounter this issue, not every > >> platform i encounter this problem. > >> > >> If enabled for all controllers, it will reduce the speed of Control transfers. > >> So i think it would be better for user to enable it by their own purposes. > > > >But how do hardware vendors know to enable this? Can we trigger off of > >PCI ids? Do we need a list of quirks to show which host controllers are > >broken this way? > > > >Burying something as basic as "reliable device connection" in a DT quirk > >seems very sloppy to me. We want reliable systems, right? > > Yes, we want reliable systems. But i don't have a good ideal about this issue. > when we meet this problem, and from the dwc-usb3 controller datasheet,we know > enable one bit in dwc-usb3 controller's register can fixed this issue. > > Of course, i can list the host controllers that i used broken this way if needed. Please have a list of controller that this is needed for, and add the quirk for them only. Don't require this to be in a DT file as that will never be noticed. thanks, greg k-h
