2010-03-04 10:12:53     Nested interrupts

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2010-03-04 10:12:53     Nested interrupts

Appalayagari Sreedhar (INDIA)

Message: 86804   

 

Hi,

 

I am working with BF527 based custom board uclinux distribution linux version Linux-2.6.28.10-ADI-2009R1. I have the USB HC and LCD device in the system. both isrs are not nested it is working fine without any crash.

 

but i could see some interrupts missing for LCD, so i tried to enable the nesting. The system crashes immediately as soon as i tried open the device.

 

I have given the attribute for nesting for interrupt handler.

 

Could you please help me what i am doing wrong.

 

Thank you, Sreedhar

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2010-03-04 10:17:31     Re: Nested interrupts

Mike Frysinger (UNITED STATES)

Message: 86805   

 

interrupts are always nested, both by higher levels as well as self-nesting.  there are no options to turn this off.  the only thing you could do is run the irq handler with all interrupts disabled.

 

so i really dont understand what you're trying to ask.

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2010-03-05 10:07:16     Re: Nested interrupts

Appalayagari Sreedhar (INDIA)

Message: 86872   

 

Dear Mike,

 

The interrupts are nested but i am facing the lcd interrupts missing when i do the usb access.

 

where could be the problem please suggest where to probe.

 

Thank you, Sreedhar

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2010-03-05 10:16:19     Re: Nested interrupts

Mike Frysinger (UNITED STATES)

Message: 86873   

 

if the USB takes too long to process and holds things off, then you're going to miss an interrupt.  if the LCD is more important to you, then make sure it has a higher priority interrupt so that it can fire even while the USB is processing, and make sure the USB handler doesn't run with interrupts disabled the whole time.

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2010-03-09 01:09:23     Re: Nested interrupts

Appalayagari Sreedhar (INDIA)

Message: 86962   

 

Dear Mike,

 

LCD interrupt is having the high priority (7) than the USB (12). USB handler means USB interrupt handler?

 

Thank you.

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2010-03-11 10:27:54     Re: Nested interrupts

Appalayagari Sreedhar (INDIA)

Message: 87097   

 

Hi,

 

The USB and LCD interrupts are nested and also the

 

USB handler does not disables the interrupts while servicing.

 

could you help where the problem could be?

 

Thank you, Sreedhar

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2010-03-12 07:32:41     Re: Nested interrupts

Appalayagari Sreedhar (INDIA)

Message: 87135   

 

Hi Mike,

 

The USB HC driver is disabling the nesting while it does the data transfers.

 

so we need to reduce the "blocks of data per data transfer" to a smaller value so that time will be provided for LCD for sevicing its intrrupts.

 

Could you please tell me where i should probe and change the code in the kernel for reducing the blocks of data ?

 

please let me know do you need more information

 

Thank you, Sreedhar

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