ah, there is another speed limit i forgot to mention, interrupts and fifo
when receiving, the PL011 can only hold 16 characters in the rx fifo
at 3mbaud linux has to stop and read the fifo over 18750 times per second, or it will risk an overflow
but dma can help
hardware flow control can be turned on, so the remote node will stop transmitting (but a clock gen obviously cant respect that)
and the overflow flag is present in the fifo word
check dmesg to see if it mentions dma being enabled and/or if overflows are occuring
when receiving, the PL011 can only hold 16 characters in the rx fifo
at 3mbaud linux has to stop and read the fifo over 18750 times per second, or it will risk an overflow
but dma can help
hardware flow control can be turned on, so the remote node will stop transmitting (but a clock gen obviously cant respect that)
and the overflow flag is present in the fifo word
check dmesg to see if it mentions dma being enabled and/or if overflows are occuring
Statistics: Posted by cleverca22 — Fri Apr 12, 2024 2:42 pm