UART driver: read function

Joel Sherrill joel.sherrill at oarcorp.com
Fri Mar 20 15:12:46 UTC 2015



On 3/20/2015 10:12 AM, Sebastian Huber wrote:
> ----- Daniel Krüger <daniel.krueger at systec-electronic.com> schrieb:
>> Beside some problems/differences between newlibc and glibc, one 
>> RTEMS-specific questions remains unanswered:
>>
>> What is the right implementation for the UART driver read function 
>> (console_fns.deviceRead)? It seems to be implemented differently from 
>> target to target. Some implementations return -1 if the receive FIFO is 
>> empty and some implementations do a busy waiting for new characters.
> The new Termios device API is documented here:
>
> https://docs.rtems.org/doc-current/share/rtems/html/bsp_howto/Console-Driver.html#Console-Driver
>
> A busy wait in the polled read handler is a driver bug.
And it have been for a LONG time. :)
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-- 
Joel Sherrill, Ph.D.             Director of Research & Development
joel.sherrill at OARcorp.com        On-Line Applications Research
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