In message 20030526150145.GO24207@pengutronix.de you wrote:
On Mon, May 26, 2003 at 04:46:05PM +0200, Wolfgang Denk wrote:
[about flow control]
No there is none, and there is no need for one.
... as the kermit protocol ensures that packets with incorrect checksums are resent.
Flow control and checksums address two different kinds of problems. While checksumming can detect the effects of overrun problems, flow control cannot solve the other problems that can cause checksum errors.
So far, in all cases I have seen with U-Boot (including the pre- decessor projects PPCBoot and ARMBoot) the CPUs were fast enought o easily handle serial downloads using both "loadb" and "loads" at least at 115200 bps. Without any need for flow control.
I don't think so. Even at high baud rates (like 115200 bps) there is more than enough time to receive characters through the serial line - remember that U-Boot is strictly single-tasking, so the CPU has nothing better to do but to wait for characters.
Nevertheless there may be situations where for example cables make problems, so using a mechanism which checks if the data is correct is not the worst idea.
But this has nothing to do with flow control.
You are right, a protocol with error checking and recovery (like kermit binary protocol) _is_ superior to a protocol without or no protocol at all - but this was not the topic here.
Best regards,
Wolfgang Denk