Hi Wolfgang, On Dec 15, 2012 6:30 PM, "Wolfgang Denk" <w...@denx.de> wrote: > > Dear Graeme Russ, > > In message <50cbd313.60...@gmail.com> you wrote: > > > > I can give you an example - Remote Telemetry Units (RTUs). They usually > > have a number of serial ports. The number of ports may vary based on the > > sub-model. Some ports may be RS-232, some may be RS-485 or RS-422. > > Depending on what additional devices you want to communicate with, you may > > need to use the 'console/diag' port to connect to a real device. So what > > you want to do is route console to another port (if available) or even > > netconsole. > > Netconsole is always an option, and I think we also support switching > to other serial ports here and there (after relocation, that is). > > But if you need console output before relocation (i. e. during > debugging), then I do not see why we cannot demand that the console > port is statically configured, and that you need corectly configured > images to have an early working console.
I have seen situations where console output by the bootloader messes up attached serial devices hence effectively dropping the serial port count by one. Pre-console buffer helps a lot (no console output until we know where to send it to). But that kills early debug. > > > I do get your point of view. But I think a combination of storing the > > dynamic console info in a DT format, the pre-console buffer and getting DT > > available as early as possible can yield a 'non-cludgy' solution. For board > > or SoC vendors who, for whatever reason, have implemented non-DT storage of > > hardware enumeration data they will be stuck with the penalty of having to > > translate that data into DT format before it can be parsed by U-Boot. Maybe > > this could be done in SPL. Yes, it's a hack, but if it can't be worked > > around, push it as low as possible and as far away from the U-Boot core as > > possible > > I mostly agree here. But I still fail to see why we havet os upport > this combination of early and dynamic - and only this is what causes > some issues. The situations I have seen can be resolved by pre-console buffer and console configured in env. If the hardware is playing up, a factory reset to default console (without using pre-console buffer) suffices (the device is on the bench with nothing attached). But then we are back to the board specific/pre-DT problem. Regards, Graeme
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