Problem faced while using workqueue in the character driver.

Problem faced while using workqueue in the character driver.

[Misbah khan]

Hi all,

I am working on a character driver for FPGA, in which i am using a blocked
read call on workqueue. The read call will be unblocked by the Interrupt
from the Fpga to PPC Cpu.

The problem is that if the process is in blocked mode and then an Interrupt
occurs the system gives kernel Panic where as it get unblocked and start
reading the data but very soon it gets crashed.

Please send me your suggessins regarding the mentioned problem.
Thanks in advance 
with regard
Misbah
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Re: Problem faced while using workqueue in the character driver.

[David Hawkins]

Hi Misbah,

> I am working on a character driver for FPGA, in which i am using a blocked
> read call on workqueue. The read call will be unblocked by the Interrupt
> from the Fpga to PPC Cpu.
> 
> The problem is that if the process is in blocked mode and then an Interrupt
> occurs the system gives kernel Panic where as it get unblocked and start
> reading the data but very soon it gets crashed.
> 
> Please send me your suggessins regarding the mentioned problem.

Er, without seeing the code, its a bit difficult to suggest
anything.

Perhaps you are using work-queues incorrectly?

Take a look at:

simple_work_queue.c

In the tar-ball

http://www.ovro.caltech.edu/~dwh/correlator/software/driver_design.tar.gz

Which is described in:

http://www.ovro.caltech.edu/~dwh/correlator/pdf/LNX-723-Hawkins.pdf

There's also a more complex 'COBRA driver' here:

http://www.ovro.caltech.edu/~dwh/correlator/cobra_docs.html

Having an example of a working driver that uses work-queues
might help you.

Dave

Re: Problem faced while using workqueue in the character driver.

[Misbah khan]

hi David

Thanks for your reply I really appreciate it from the heart.

The problem is solved now ,Actually I was using a kernel timer in open call
(to run for the first time which ever application would open it and deleting
the timer for the last exit ) to simulate for an Interrupt in the same
driver. There i did mistake in the implimentation in the logic and as a
consiquence of which it was crashing the system and not because of the
workqueue.

thanks 
misbah

David Hawkins-3 wrote:
> 
> Hi Misbah,
> 
>> I am working on a character driver for FPGA, in which i am using a
>> blocked
>> read call on workqueue. The read call will be unblocked by the Interrupt
>> from the Fpga to PPC Cpu.
>> 
>> The problem is that if the process is in blocked mode and then an
>> Interrupt
>> occurs the system gives kernel Panic where as it get unblocked and start
>> reading the data but very soon it gets crashed.
>> 
>> Please send me your suggessins regarding the mentioned problem.
> 
> Er, without seeing the code, its a bit difficult to suggest
> anything.
> 
> Perhaps you are using work-queues incorrectly?
> 
> Take a look at:
> 
> simple_work_queue.c
> 
> In the tar-ball
> 
> http://www.ovro.caltech.edu/~dwh/correlator/software/driver_design.tar.gz
> 
> Which is described in:
> 
> http://www.ovro.caltech.edu/~dwh/correlator/pdf/LNX-723-Hawkins.pdf
> 
> There's also a more complex 'COBRA driver' here:
> 
> http://www.ovro.caltech.edu/~dwh/correlator/cobra_docs.html
> 
> Having an example of a working driver that uses work-queues
> might help you.
> 
> Dave
> _______________________________________________
> Linuxppc-embedded mailing list
> Linuxppc-embedded@ozlabs.org
> https://ozlabs.org/mailman/listinfo/linuxppc-embedded
> 
> 

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