Hi Angelo, On 18/10/17 07:18, Angelo Dureghello wrote: > On 16/10/2017 01:08, Finn Thain wrote: >> On Sun, 15 Oct 2017, Angelo Dureghello wrote: >> >>> Hi all, >>> >>> i was trying a file transfer with xmodem-1k and uClinux "rx" on the >>> mcf54415 stnmark2 board side. >>> >>> This using a recent mainline kernel: >>> / # cat /proc/version >>> uClinux version 4.14.0-rc4stmark2-001-00118-g811fdbb62a9d >>> / # >>> >>> So, as per xmodem-1k, i send 3 bytes header, a 1024 bytes block, and 2 >>> bytes crc16. But "rx" timeouts waiting the block. >>> >> >> What is the fastest baud rate that will work? >> >>> Adding some traces to "rx", it timeouts since some bytes (5 to 10) >>> randomly positioned in the block are not received. Of course they have >>> been sent (scope checked). >>> >>> The same 1024 bytes transfer in u-boot (y-modem) always succeed. >>> >> >> Does u-boot need to do any retransmissions? (If it polls the UART, it >> could probably avoid any fifo overflow.) >> >> You may also want to try lrzsz. >> >>> Since mcf54415 has a 4 slots RX fifo UART, >> >> Ouch. At 115200 baud, that FIFO overflows after about 347 microseconds. If >> the kernel takes one interrupt per 4 bytes, you're looking at thousands of >> interrupts per second. Add a little unexpected interrupt latency (say, 50 >> microseconds) and the next byte gets lost. >> > > thanks for explaining this. > > Well, if i understand properly, this mcf54415 CPU has 2 interrupts flags > that can be checked: > > RXRDY, for one or more character received (current mcf.c seems to use > this flag) and > FFULL, for all 4 fifo slots full. > > So we probably have even more interrupts per second right now. > > I am at 115200, will try to decrease, and also, will try zmodem in case.
Can you use hardware flow control (the "crtscts" stty setting)? You will need to use a serial cable with RTS and CTS signals wired, and also for the sending end to be set for it. The ColdFire UART has hardware level support for automatically driving RTS/CTS when FIFO is full. Regards Greg -- To unsubscribe from this list: send the line "unsubscribe linux-m68k" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
