On Wed, 29 Oct 2003, Julian Back wrote: > Here is the relevant section from the device manual, it may explain the > situation more clearly: > > "18.6.2 Forcible Stall by Application > > The application uses the EPSTL register to issue a stall request for the > USB function module. When the application wishes to stall a specific > endpoint, it sets the corresponding bit in EPSTL (1- 1 in figure 18.13). > The internal status bits are not changed at this time. When a > transaction is sent from the host for the endpoint for which the EPSTL > bit was set, the USB function module references the internal status bit, > and if this is not set, references the corresponding bit in EPSTL (1-2 > in figure 18.13). If the corresponding bit in EPSTL is set, the USB > function module sets the internal status bit and returns a stall > handshake to the host (1-3 in figure 18.13). If the corresponding bit in > EPSTL is not set, the internal status bit is not changed and the > transaction is accepted. > > Once an internal status bit is set, it remains set until cleared by a > Clear Feature command from the host, without regard to the EPSTL > register. Even after a bit is cleared by the Clear Feature command (3-1 > in figure 18.13), the USB function module continues to return a stall > handshake while the bit in EPSTL is set, since the internal status bit > is set each time a transaction is executed for the corresponding > endpoint (1-2 in figure 18.13). To clear a stall, therefore, it is > necessary for the corresponding bit in EPSTL to be cleared by the > application, and also for the internal status bit to be cleared with a > Clear Feature command (2-1, 2-2, and 2-3 in figure 18.13)."
Judging from that, it looks like clearing a halt requires letting the device software know by sending some vendor-specific message, in addition to simply sending a Clear Feature command. You have to wonder why they designed their controller that way. This doesn't bode well for the SuperH's ability to cope with "flash" BBB. Alan Stern ------------------------------------------------------- This SF.net email is sponsored by: SF.net Giveback Program. Does SourceForge.net help you be more productive? Does it help you create better code? SHARE THE LOVE, and help us help YOU! Click Here: http://sourceforge.net/donate/ _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
