Re: [PATCH] serial: DCC(JTAG) serial and console emulation support

Mike Frysinger
2010-10-07T19:49:19Z

On Thu, Oct 7, 2010 at 15:39, Daniel Walker wrote:
> On Thu, 2010-10-07 at 15:25 -0400, Mike Frysinger wrote:
>> On Thu, Oct 7, 2010 at 14:36, Daniel Walker wrote:
>> > Many of JTAG debuggers for ARM support DCC protocol over JTAG
>> > connection, which is very useful to debug hardwares which has no
>> > serial port. This patch adds DCC serial emulation and the console
>> > support. System timer based polling method is used for the
>> > emulation of serial input interrupt handling.
>>
>> why use serial_core at all ?  seems like you could just use the tty
>> layer directly.  i did that with drivers/char/bfin_jtag_comm.c.
>>
>> although, there's the suggestion in the air that my jtag driver could
>> be converted to the HVC framework to even further simplify things.
>> but no one thinks it should be serial_core :).
>
> It will actually create a serial port on ttyS* if you want it to.. It
> could be debatable if that's useful, but I didn't rip that out because
> Hyok had that in his original code (he thought it was useful) ..

i dont think hijacking the "ttyS" namespace is acceptable, even if
it's behind a Kconfig. other people have tried in the past (myself
included) and been shot down. sounds like a shim for crappy userspace
apps that blindly assume /dev/ttyS*. is that really an issue anymore
though now that things like /dev/ttyUSB* are so common and people are
used to picking between multiple serial sources ?
-mike