DRA74x PTP clock anamoly

K Md Feroz Irfan

Hi Champs

A Customer has found a workaround to make the gptpd work on the XSe platform.

He sees that the kernel ptp clock works fine, but the time stamp value seems to shifted 6% from the value it is supposed to be.

Currently he has added hard coded value to compensate this 6 % shift by a multiplier, and then our gptpd code has started to work.

Question 1: Do you have an explanation for this discrepancy?

Question 2: Can we get access to the forward on J6 that controls the HDMI output for our display synchronization scheme to be added.

Thanks,

Sincerely,

Feroz

0 Yanko Todorov-XID over 9 years ago

Hello Feroz,

We are working on your question but,

Please move your question in the INTERNAL Automotive Processor and OMAP Forum - https://e2e.ti.com/support/omap/int_omap/f/941.aspx

I notice that the information about DRA74x requires NDA agreements.

Best regards,

Yanko

0 Yanko Todorov-XID over 9 years ago in reply to Yanko Todorov-XID

Hello Feroz,

I asked the AVB experts about your questions.

The suggested workaround to overcome this issue is:

"See these lines in the Linux tree for GLSDK (arch/arm/boot/dts/dra7.dtsi):
cpts_clock_mult = <0x80000000>;
cpts_clock_shift = <29>;"

The new multiplier value is 0x784cfe13 = 0x80000000 * 250/266

Best regards,

Yanko

0 K Md Feroz Irfan over 9 years ago in reply to Yanko Todorov-XID

Thank you Yanko!

Customer will get back on nay futher queries here...

Best Regards

Feriz

Processors forum