Query regarding i.mx6 Dual SabreSD, HSync VSync in case of HDMI/LCD

[ashwinrase]

Hi,

We are using i.mx6 Dual SabreSD. And connected HDMI/LCD as output device on video 0.

We measured DE(Data ready), HSync and VSync signals on EVM. All signals are (active) even if we don't send any data.

And all became off As soon as HDMI/LCD went in sleep mode.

Why HDMI/LCD need HSync, VSync and DE even if there is no data on lines?

How dose display understand if any data should be displayed or not using these signals?

Thanks and Regards,

Rinkesh Patel

[igorpadykov]

Hi Ashwin

IPU produces sync signals after initialization,

even you did not sent data, actually IPU sends data from

buffer in DDR, it always has some data, for example zero or previous data.

IPU has hardware mechanism allowing to check if new data are arrived,

as described in sect.37.1.2.1.6.2 Update Of The Display Buffer IMX6DQRM

LCD may blank after some time, as discussed below

Disable screen blanking on i.MX6 running Yocto

also one can check if enabled screenserver or lcd monitor

can have own "sleep" mode after some time inactivity.

Best regards

igor

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