confusion about few interrupts on OMAP3530

I will try to answer you,

(1)In DisplaySubSystem(DSS), what is the exact difference in usage of VSYNC and FRAMEDONE interrupts? Like FRAMEDONE interrrupt, VSYNC interrrupt also occurs after display of one frame is done..Can anyone please tell me the exact difference in usage of these two interrupts?

[Vaibhav] FRAMEDONE interrupt only gets used before disabling output stopping the output, to make sure that active frame is complete. VSYNC interrupt is the one which gets used to service every frame/field.

(2)In case of TV, there are different interrupts EVSYNC_ODD and EVSYNC_EVEN to indicate completion of odd and even fields display. So, is it not requried to enable or check for VSYNC interrrupt in case of a display driver for TV?

[Vaibhav] VSYNC interrupt is explicitly used for LCD output and other two (EVSYNC_EVEN and EVSYNC_ODD) is used for TV out.

I hope your doubts are clear now.

Thanks,

Vaibhav

Hi Vaibhav,

Thank you for your reply. 

Yes understood most of it,  we use VSYNC interrupt to service every field/frame. 

One more question in mind is,  "FRAMEDONE interrupt only gets used before disabling output stopping the output, to make sure that active frame is complete. " So, do we need to check for  FRAMEDONE interrupt and there by disable output after completion of every frame? and why is disabling of output for each frame and re-enabling for consequent frame needed?

Thanks,

Srilatha.

No, we don't disable display on every frame.

FRAMEDONE interrupt becomes important, for example, when you reset the DSS and display is already on. The root-cause could be anything, may be SYNCLOST interrupt.

Please refer to the TRM,

    - 7.5.1 Display Subsystem Reset

    - 7.3.2.2.1 DISPC Interrupt Request

Thanks,

Vaibhav