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. --
i was wondering if the mcf.c uart driver is not fast enough to read the data, or, where the "linux" limitation could be. Regards, Angelo Dureghello -- To unsubscribe from this list: send the line "unsubscribe linux-m68k" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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