DS90UB941AS-Q1: DS90UB941AS-Q1

Hi,

I cannot see your images that you attached, can you try to attach them again?

What do you mean lock is not stable when the 941 lost DSI singal? Without DSI signal into the 941 the FPD-Link will not come out of the 941 properly. Since your DSI is using DSI Continuous Clock Mode then the 941 will not have a clock source if the DSI is gone.

Regards,

Michael W.

Hi Michael,

I re-uploaded the images again.

Normal status:

Lock is stable even if DSI is no signal.

Note: DSI will be gone when system enter to suspend mode.

abnormal:

Lock is un-stable when system enter to suspend mode.

Hi,

Can you provide a register dump of the 941AS to better debug this issue?

Regards,

Michael W.

Hi Michael,

I asked our software.

Android  will occupy I2C channel.

He need to rebuild OS if would like to dump the register table.

We try to disable PCLK_AUTO before enable DSI.

Lock pin is stable even DSI signal has gone.

We think FPD-link maybe not switch successful between PCLK and internal clock.

Any side effect if we disable PCLK_AUTO?

Please advise.

Thank you.

Hi,

What is your MODE_SEL set to? What is the register 0x56's value? I am not sure, of the side effects of disabling the PCLK_AUTO, are you seeing video flickering when PCLK_AUTO is disabled or enabled?

Regards,

Michael W.

Hi Michael,

We do not see video flickering when PCLK_AUTO is disabled or enabled?

We also do not change 0x56 value via software.

HW strap setting as below.

MODE_SEL0 is mode3

MODE_SEL1 is mode0

Relation schematic is attached.

Mode941.pdf

Hi,

I believe that the issue is that the DSI source is not in continuous clock mode and when the DSI clock is not switching the 941AS does not have a reference clock to use to generate the FPD-Link signal.  Please reconfigure the DSI source's clock to send out the DSI clock always. 

Regards,

Michael W.

Hi Michael,

Does mean that DSI need to disable before system suspend?

The flow should be as below,

Disable DSI→ Register setting→ Enable DSI

Disable DSI before system suspend→ System resume→ Enable DSI

Another question,

FPD-link fail is randomly when system suspend(lost DSI signal)

Does FPDlink has an internal reference clock when DSI lost but the function is failed?

Hi,

I do recommend following the steps you have said.

Disable DSI→ Register setting→ Enable DSI

Disable DSI before system suspend→ System resume→ Enable DSI

The 941AS does have an internal clock that can be used as the reference for the FPD-Link signal, but this clock is recommended for only test and debug function because its jitter is too large. to enable this internal clock source set the BRIDGE_CLK_MODE to b'10.

Regards,

Michael W.