rtems_message_queue_receive / rtems_event_receive issues

[Sebastian Huber]

On 20/09/2018 15:48, Catalin Demergian wrote:
> Hi,
> I'm using
> #define BSP_ARMV7M_IRQ_PRIORITY_DEFAULT (13 << 4)
> 13*16=208 > 0x80=128, so I should be on the safe side.
>
> what do you mean by operating system services ?

Everything which uses rtems_interrupt_disable() or 
_Thread_Dispatch_disable().

> like rtems_event_send in ISR ?

Yes.

> is there other way to handle USB data other than copy data in a buffer 
> in ISR and signal a kernel
> task (that is doing rtems_event_receive) with a rtems_event_send call ?

The message queues should work for this purpose. If the data is large 
enough, then it is better to copy it only once and use a custom queue 
implementation.

>
> regards,
> Catalin
>
> On Wed, Sep 19, 2018 at 5:58 AM Mingyu Li <lmy2010lmy at gmail.com 
> <mailto:lmy2010lmy at gmail.com>> wrote:
>
>     Hi Catalin.
>
>     I find the problem you encountered interesting. I hope to offer
>     some hints that might be helpful to you:
>
>     1. use a user task to first rtems_event_send
>     then rtems_event_receive, in order to make sure the internal IPC
>     of RTEMS kernel you are using (4.11.2) works as expected.
>     2. ensure to disable/lock interrupts while operating the
>     message_queue inside USB ISR. Try to check if clock ISR is still
>     responded when USB ISR exits, so that the kernel task can be
>     scheduled to obtain the message.
>
>     Best regards,
>     Mingyu
>
>     2018-09-18 20:20 GMT+08:00 Catalin Demergian <demergian at gmail.com
>     <mailto:demergian at gmail.com>>:
>
>         Hello,
>         I am using RTEMS 4.11.2 and I tried first to use RTEMS message
>         queues in my USB FS driver.
>         I'm populating the queue from the ISR and then use
>         rtems_message_queue_receive from a kernel task to
>         read the messages. After some debugging sessions I came to the
>         conlusion that rtems_message_queue_receive function
>         hangs even if there are messages in the queue. (manpage says
>         it should return immediately if there is at least one message
>         in the queue; in my case the queue gets full, but still the
>         function hangs)
>
>         I tried then rtems_event_receive. I used my own queues and
>         from ISR I only called rtems_event_send; the same issue
>         happened again, this time rtems_event_receive hangs even if I
>         see the event was raised (with task command in the shell)
>
>         My question is: are there any known issues/bugs with these
>         functions ?
>
>         thanks,
>         Catalin
>
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>
>
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-- 
Sebastian Huber, embedded brains GmbH

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