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Forum Post: RE: Is there any demo code of SRIO module on Quad-DSPC 8681 PCIe card available?

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[quote user="David George"]

1.

I note that pathmode = 4 in the example,it means that you can config full lane for transfer.

pathmode = 4;   //means that one port 4x

for(i = 0; i < 4; i++)
        CSL_SRIO_SetPLMPortPathControlMode (hSrio, i, pathmode);

But why such config can work successfully? I don't think you can config the SRIO

for one port 4x mode on DSPC-8681E.As I know,DSP0(c6678) has 4 lanes .But

in 8681 DSP0 only use one lane to connect DSP1 and use another lane to connect

DSP3.I am not sure DSP0 and DSP1 use lane0 or lane1 or lane2 or lane3.So do DSP0

and DSP3.But one thing is sure that the lane number which DSP0 and DSP1 connect with

cannot be four.Because DSP0 only have four lanes,the four lanes may be used for DSP1 and

DSP3.But four lanes of DSP0 cannot totally be used by DSP1.So,I believe that you cannot

CSL_SRIO_SetPLMPortPathControlMode (hSrio, i, 4) to  set all the ports.Because DSP0 and

DSP1 cannot use all the lanes for transfer. Transfer Pair (DSP0-DSP1) and Transfer Pair (DSP0-DSP3)

will share all the four lanes.Anyhow,I don't believe you can set pathmode = 4.

       In fact ,such config pass the SRIO test .So why?

[/quote]

Yes Path_mode = 4 means 4x port.  If you spend some time reading the RapidIO Serial specification, you will see that the state machines do allow for a 4x capable port to run in 1x mode.  It is a fall back, if 4x operation can't be established because of a bad lane for example, the 4x port can establish a 1x port on either lane 0 or lane 2. 

[quote user="David George"]

Another hand,I try to modify pathmode = 0. it meas that four 1x ports.

I believe pathmode = 0 should be suitable and wright.Still the reason I confirm above that

DSP0 and DSP1 only connect each other with one lane,Assume it is lane0.So pathmode =0.

At least it should be 1x port not 4x port.But the result is disappointed.When I modify code like below

for(i = 0; i < 4; i++)
        CSL_SRIO_SetPLMPortPathControlMode (hSrio, i, 0);

The example cannot pass the test.So, Where make mistakes? Does my guess standup?

Where can I get the schematics of DSPC-8681E,So I can know how many lanes and which lanes

do DSP0 and DSP1 use .So I can config SRIO port correctly .How to treat this problem?

Who leads the bad result?

[/quote]

Not sure if you are seeing errors, or if the test you are running in this setup is not sending the packets to the write port.  The schematics would have to come from Advantech directly.

Regards,

Travis


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