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DSS Software reset

abraxas
Prodigy 230 points

Hello,

i want to change the dss pixel-clock.

i'm working with linux kernel 2.6.32 on an OMAP3EVM. so the DSS-driver already uses the DSI PLL, which is fine.

i progammed the frequency-management according to TRM p. 2379, but i can't complete the DSS restart procedure. Are there any more clocks i have to activate?

i attached part of my source-code, if you want to take a look.

5504.dss_software_reset.zip

some more questions:

1) after the software reset, do i have to setup every DSS register again or the prior settings stored?

2) i measured, that the pixelclock has quite a jitter. Is this correct? Otherwise it's due to the adapter-board i created...

 

kind regards,

christoph

 

  • 0
    Mastermind 9310 points

    1) After software resetting the DSS controller, you have to reconfigure all the registers as those have been reset to their default state. If you changed your PLL, I suggest you make the necessary changes in the registers at the initialization of the driver, this way you won't have to reset the DSS controller. Or maybe you want to change your PLL dynamically? If so let us know what the exact scenario you want to achieve.

    2) What your adapter board changes exactly? Did you add an oscillator as the source of the DSS PLL? Please give us more details on this for us to understand what you are trying to change here.