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host controller neglects sending 'ISO IN' request
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host controller neglects sending 'ISO IN' request

yoshitsugu posted on 24 Feb 2012 1:32 AM PST
Member
3 Forum Posts
I'm testing transfer performance with FX3 DVK (Rev2). in BULK IN transfer, max packet size = 1024, burst length up to 16, everythig seems OK. the transfer rate is around 120MB/s. (moderate...) but in ISO IN transfer, max packet size = 1024, burst length = 16, the host controller sometimes neglects sending 'IN' request approximately 3ms. I mean no "ACK TP" (it's necessary to start ISO IN transfer) appears on the USB bus during that time. I think this problem is a matter of host chip or driver. Have anyone experienced this kind of problem? and, how did you solve it? - application requests 131072 (=1024*16*8) bytes data by calling BeginDataXfer. - USB 3.0 I/F card is connected to PCIex1 gen2 port. - the host chip is Renesas D720200. Driver version is 2.0.30.0. - Cypress driver (cyusb.sys) version is 1.00.0000.001 Best regards,


Re: host controller neglects sending 'ISO IN' request

aasi posted on 24 Feb 2012 01:48 AM PST
Cypress Employee
1073 Forum Posts

Hi,

How many packets per transfer are you requesting at a time and how many transfers are  you queueing at a time?

Regards,

Anand

Re: host controller neglects sending 'ISO IN' request

yoshitsugu posted on 25 Feb 2012 12:55 AM PST
Member
3 Forum Posts
Hi, Anand-san. in device side, I described SuperSpeed Endpoint Companion descriptor as bMaxBurst = 15, bmAttributes(Mult) = 0, wBytesPerInterval = 16384 (1024*16). So, I'm requesting 16 packets (16384 byts) per transfer. in host side, I'm queueing 8 transfers at a time by calling BeginDataXfer, with argument 'length' = 16384 * 8. the pause of 'IN' request occers in between transfer and transfer. (after several 16-burst transfer is successful, then pause...) it occurs even though request queue still remains. it seems that the host is not able to prepare the receive buffer for a while. Regards,

Re: host controller neglects sending 'ISO IN' request

aasi posted on 29 Feb 2012 10:24 PM PST
Cypress Employee
1073 Forum Posts

Have you tried using streamer/screamer that comes with superspeed suiteUSB? Are you seeing the same behavior with that?

Regards,

Anand

Re: host controller neglects sending 'ISO IN' request

yoshitsugu posted on 01 Mar 2012 10:43 PM PST
Member
3 Forum Posts
I tried the streamer application that comes with the USBSuite. The pause had occurred in between Xfer and Xfer. For example, when Xfer is 8, the pause occurs after continuous 8 transfers. Xfer is 16, the pause occurs after continuous 16 transfers. The pause occurs every after requesting Xfers, 'Xfers to Queue' has nothing to do with this pause. In conclusion, I found out that this pause is caused because the kernel-mode receive buffer is attached only after calling BeginDataXfer. The application runs in user-mode, no matter how many requests the application sent, the pause occurs after the all driver's requests have been completed. In ISO IN transfer, data comes incessantly. So the driver is required to have a multiple buffer to compose ring buffer not to lose incessant coming data. Is Cypress driver considered in this respect? Regards, By the way, how do I insert 'line feed' in this text-box?

Re: host controller neglects sending 'ISO IN' request

aasi posted on 01 Mar 2012 07:40 PM PST
Cypress Employee
1073 Forum Posts

That is strange. The asynchronous method is there just to avoid this issue (while using xferdata() method the OS will schedule the next xferdata only after the previous xferdata completes leading to delay). Let me see if I'm able to replicate the same.

Regards,

Anand

Re: host controller neglects sending 'ISO IN' request

aasi posted on 01 Mar 2012 07:41 PM PST
Cypress Employee
1073 Forum Posts

 for line-feed you can use

Enter

or
shift + enter.

Regards,

Anand



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