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BUK IN DP burst not according to U3 Spec?
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BUK IN DP burst not according to U3 Spec?

Owen Chang posted on 12 Jul 2012 7:28 PM PST
Senior Member
15 Forum Posts

I found the FX3 will sometimes send 2 consecutive DPs, then wait for Host ACK. but according to USB3.0 spec 8.12.1.2 (BUK IN Transaction), device don't have to wait for Host ACK [BURST], so in my case Host will first send ACK with NumP=8, it means device is allowed to response with up to 8 consecutive DPs without waiting Host ACK. what is the reason of FX3 not following spec on this part? is it because the bandwidth of FX3 not enough? 

please see my attached file for more detail.

thanks.

 

Re: BUK IN DP burst not according to U3 Spec?

Owen Chang posted on 12 Jul 2012 07:30 PM PST
Senior Member
15 Forum Posts

 sorry, here is the log file

Re: BUK IN DP burst not according to U3 Spec?

RSKV posted on 13 Jul 2012 04:26 AM PST
Cypress Employee
655 Forum Posts

What is the host controller that you are using?.

Are you using a FX3 DVK with engineering sample on it?.

Regards,

sai krishna.

Re: BUK IN DP burst not according to U3 Spec?

Owen Chang posted on 16 Jul 2012 06:29 PM PST
Senior Member
15 Forum Posts

I am using TI TUSB7340 & NEC Host, but i don't think it is host issue. 

I have modified engineering sample to FullHD UVC, but the modification is just the bigger payload.

perhaps you could do the same at your end to see what's really happening.

BR,

Owen

Re: BUK IN DP burst not according to U3 Spec?

RSKV posted on 17 Jul 2012 11:26 PM PST
Cypress Employee
655 Forum Posts

Hi Owen Chang,

I don't think FX3 is waiting for the ACK from the host side.

It is just that the host controller is sending the ACK to FX3 before it recieves the total number of packets.

Regards,

sai krishna.



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