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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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Hi,Travis:

About the CSL_SRIO_SetPLMPortPathControlMode,I want to say more .

I run the example in the pdk1.1.2.5 for SRIO Throughput on DSPC-8681E.Although

I have passed the test and the result give the performance.But I cannot understand

why I can pass the test.By the way,I modify some obvious places such as from loopback

to Normal (device to device ) and make example suitable for DSPC 8681E to move

data between DSP0 and DSP1.Luckily, I load consumer out to DSP0 and load producer

out to DSP1 and run successfully. But I don't know why?It seems unreasonable .

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?

2.

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?

 

Best Regards!


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