Peter, On Wed, Dec 12, 2018 at 10:04:25AM +0800, Peter Chen wrote: [snip] > > >I strongly advise against using dev_dbg() for debugging. Even more so > > >inside your IRQ handler. > > Felipe, I use Dynamic Debug for debugging, and show debug messages with > "dmesg" after testing/debugging. I see dwc3 using trace, any benefits > for switching > to trace? The benefits I see are - *by default*, the debug log doesn't have to go through uart console, which is slow. I typically 'cat trace_pipe' from a telnet which is much faster then uart. But Dynamic Debug log by default got printed on uart, I have to set printk level to not print them, which is an extra step. - tracepoint uses one place to decode the message vs DD has to repeat the similar print statement in the code; and tracepoint decodes it offline which reduce the kernel runtime overhead too. - with tracepoint, it is easier to turn on debug for a specific group of messages. - you can adjust the ftrace buffer size at runtime. can we do that for printk? I don't remember. Regards, -Bin.
