Handling GS_USB_BREQ_SET_TERMINATION and GS_USB_BREQ_GET_TERMINATION requests
fenugrec opened this issue · 2 comments
Continuing discussion from #113.
There seems to be a difference in behaviour between old firmware, and new firmware compiled without TERM_PIN , when receiving those new requests.
Originally, in USBD_GS_CAN_Config_Request(), any unsupported request falls through to the default, USBD_CtlError(pdev, req); this seems to be also the case in the new code but with a few added steps (adds about 30 bytes; gcc isn't quite able to optimize out everything unless maybe when compiling with -flto)
in USBD_GS_CAN_EP0_RxReady(), previous code would do nothing and return USBD_OK, but now we USBD_CtlError(pdev, req); .
I suspect that USBD_GS_CAN_EP0_RxReady will never be called as the USBD_GS_CAN_Config_Request drops it out first; I.E. the check there is uneeded.
unless you replace the param_u32 with a constant, the if statement will not be optimized out.
The memcpy can not be optimized out.
This is optimized out:
case GS_USB_BREQ_SET_TERMINATION:
set_term(req->wValue, (uint32_t)hcan->ep0_buf);
break;
This is insufficient for setting an invalid terminating resistor when it's enabled.
found it. PR coming in hot