serial: 8250: RX hang issue

serial: 8250: RX hang issue

[Pradeep Kumar]

Hi All,
I am working on a mobile development platform and performing some stress
warm boot tests using UART debug console(which is using serial 8250 driver
for console).

I am getting device debug console UART RX hang after iterations > 1500.
after this issue am not* able to issue any command. Able to see logs
though.

Later I kept some debug prints in isr and able to see that device is able
to generate interrupts when some data is received. So I came to conclusion
that some malfunctioning is happening  in upper layer not sure which layer
has this problem. Can some one give some ideas at which layer I can check?

One more observation is when I perform a open and close calls on debug UART
port(in my case ttyS0) while device is in UART RX hang state, then I notice
the UART console RX again below active and able issue commands from UART
console itself.
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serial: 8250: RX hang issue

[Peter Teoh]

On Tue, Nov 22, 2011 at 12:10 AM, Pradeep Kumar <pradeepkernel@gmail.com>wrote:

> Hi All,
> I am working on a mobile development platform and performing some stress
> warm boot tests using UART debug console(which is using serial 8250 driver
> for console).
>
> I am getting device debug console UART RX hang after iterations > 1500.
> after this issue am not* able to issue any command. Able to see logs
> though.
>

I suspect the buffer has reached it limits....


>
> Later I kept some debug prints in isr and able to see that device is able
> to generate interrupts when some data is received. So I came to conclusion
> that some malfunctioning is happening  in upper layer not sure which layer
> has this problem. Can some one give some ideas at which layer I can check?
>
> One more observation is when I perform a open and close calls on debug
> UART port(in my case ttyS0) while device is in UART RX hang state, then I
> notice the UART console RX again below active and able issue commands from
> UART console itself.
>
> Open and close perhaps clear the buffer, and so the communication can
restart again?   I am not sure if the buffer at the host or client side is
the culprit, or both.   What ever it is, it could be that the round robbin
clearing of buffer is not working.


>
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> Kernelnewbies mailing list
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>
>


-- 
Regards,
Peter Teoh
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