DM6467 display interrupt

Shruti Purohit

Hi,

Can anybody tell me when do we receive an interrupt from the display port on dm6467?

My system is running at 60 fps, so if I understand it correctly, the interrupt should be received every 16ms. But the ISR 'vpif_channel_isr' in "drivers/media/video/davinci/davincihd_display.c" is evoked in the following manner.

16milli second -> 9micro second ->16milli second -> 9micro second->16milli second -> 9micro second->16milli second -> 9micro second.....and so on.

Can this be explained?

Also, I came across this particular constraint of VPIF driver in LSP 2.00 DaVinci Linux VPIF Display Video Driver User's Guide Literature No. SPRUGA0

"For the progressive mode of display, the number of buffers must be greater or equal to three. Otherwise, call to VIDIOC_DQBUF will hang."

Why does the driver needs 3 buffers ??

Thanks and Regards

Shruti

over 12 years ago

0 Brijesh Jadav over 12 years ago

TI__Guru**** 486255 points

Hi Shruti,

Interrupt depends on the your input frame rate, since it is set to 60fps, interrupts should be coming at 16.67ms.

Regards,

Brijesh Jadav

0 Shruti Purohit over 12 years ago in reply to Brijesh Jadav

Prodigy 120 points

Exactly my point, frame rate is 60 fps I should receive an interrupt every 16ms or so approximately. So why am I receiving it at 16ms then next after 9us and again the next one at 16ms and the next one after 9us and so on??? Why alternate interrupts are received at 9us??

Thanks and Regards

Shruti

0 Brijesh Jadav over 12 years ago in reply to Shruti Purohit

TI__Guru**** 486255 points

Hi Shruti,

It could be because interrupts for both the channels are enabled. Could you check if this is the case?

Rgds,

Brijesh

0 Shruti Purohit over 12 years ago in reply to Brijesh Jadav

Prodigy 120 points

yes brijesh..it seems i am receiving interrupt for both the channels.

How can I disable the interrupt for the channel that I am not using to display?

Also can you tell me why does the drver require minimum of 3 buffers for progressive mode(in User guide its mentioned that if we give less than 3 buffers for progressive mode..driver will hang)??

Thank you

Shruti

0 Brijesh Jadav over 12 years ago in reply to Shruti Purohit

TI__Guru**** 486255 points

Hi Shruti,

Can you try disabling interrupt by commenting out request_irq? or by enabling enable_channel1(0)/ channel1_intr_enable(0). After this change, interrupt for the other channel should not come.

It needs three buffers, becase hardware uses one buffer, one is for the next frame and one is for the application, so minimum three is required.

Thanks,

Brijesh Jadav

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DM6467 display interrupt