On Fri, Feb 26, 2021 at 05:01:35PM +0100, Marc Kleine-Budde wrote: > > Is timestamp-wrapping a concern for rx-offloading? > > No, as long as you provide a proper u32 timestamp, which means wrap > around at 0xffffffff to 0x0. As the tcan4x5x has only a 16 bit > timestamp, shift it to full 32 bit, like this: > > https://elixir.bootlin.com/linux/v5.11/source/drivers/net/can/flexcan.c#L805 > > On the mcp with true 32 bit timestamp there's a wraparound every 107 > seconds at 40 MHz external clock (0xffffffff / 40000000). > > The tcan has the TSS.TCP as a prescaler and increments in bit time, > which is 5MHz max. This results in a wrap around every 13ms (0xffff / > 5000000) with a prescaler of 1. With a prescaler of 16, you can increase > this to 209ms (0xffff / 5000000 * 16), which gives an accuracy of 2 > bytes. Nice, thank you, that all sounds good. I'll get to work. :) -- Regards, Torin Cooper-Bennun Software Engineer | maxiluxsystems.com
