Anisha Kaul wrote:
>>> Thanks for the prompt reply !
>>>
>>> The tasklet I am talking about is supposed to re-set the registers of the
>>> serial port each time an interrupt occurs ! We can do this the following
>>> way in using Linux system calls :
>>>
>>> void resetRegisters (unsigned long currentlyUnused);
>>>
>>> DECLARE_TASKLET (rs232Tasklet, resetRegisters, 0);
>>>
>>> void resetRegisters (unsigned long currentlyUnused)
>>> {
>>> outb (0x83, PORT + 3);
>>> outb (0x01, PORT + 0);
>>> outb (0x00, PORT + 1);
>>> outb (0x03, PORT + 3);
>>> outb (0x01, PORT + 1);
>>> outb (0x63, PORT + 2);
>>> outb (0x08, PORT + 4);
>>> }
>> This looks like a weird use of tasklets under mainline. Moreover, they
>> are practically deprecated there.
>>
>>> How am I supposed to do this using Xenomai ?
>> Have you considered simply using the rt_16550A driver for your purpose?
>> You didn't told us your use case from an application POV, so it's hard
>> to say if the driver meets your requirements. But it does not require
>> you fiddling with hardware directly.
>>
>> Jan
>
>
> " This looks like a weird use of tasklets under mainline. Moreover, they are
> practically deprecated there."
>
> Why do you say this ?
The function you defer from interrupt context into a tasklet is
comparably cheap, specifically on modern systems. So the management
overhead is expect to be in the same dimension as the workload (you do
not gain noticeably shorter IRQ-off times this way).
>
> " Have you considered simply using the rt_16550A driver for your purpose? "
>
> I was not aware that a serial port driver for real time does exist !
> Secondly, here we are writing a robotic application where we want to stop the
> robot if we receive data 'x' or move the robot if we receive data 'y'.
> Can you tell me how can we achieve this functionality with rt_16550A driver.
Check existing examples and the RTDM serial profile documentation.
> Is rt_16550A driver fully stable ?
Yes, it's used, among other things, in robotics for many years.
Jan
--
Siemens AG, Corporate Technology, CT SE 2
Corporate Competence Center Embedded Linux
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