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eSPI Agent Core, bug in WAIT_STATE response

WFitt
Novice
443 Views

Hello,

We are using Intel eSPI Agent Core in Intel FPGA MAX 10.

Now we possibly found a bug in the Intel eSPI Agent:

The bits 15:12 ("Maximum WAIT STATE Allowed") of the General Capabilites and Configuration Register are set to 0x0 (default value). That means 16 byte time wait states max. are allowed. 

The eSPI Agent is responding always 16 bytes of WAIT_STATE before ACCEPT or DEFER regardless of the command responding to.

This behaviour could lead to much lower performance on the eSPI bus!

 

Regards

Wolfram

 

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13 Replies
hareesh
Employee
413 Views

Hi,

sorry for late responding.

can you please share your platform design file and i want to know how did you find out that issue and what steps did you followed. can you please share that information?

it helps us to identify issue.


Thanks,


TTBNSTOCK
Novice
409 Views
Good job
hareesh
Employee
402 Views

please share that information


WFitt
Novice
386 Views

Hi,

we are using an own mainboard with an Intel Elkhart Lake CPU module. The Elkhart Lake CPU is communicating via eSPI with an Intel FPGA  on our mainboard. At the moment we use eSPI with 20 MHz eSpi clock and Single I/O mode. The IP clock is 130 MHz.

During CPU BIOS booting we can see many transactions between Host (CPU) and Agent (FPGA):

21 00 08 10               GET CONFIGURATION
21 00 20 C8               GET CONFIGURATION
22 00 20 01 00 07 00 01       SET CONFIGURATION
21 00 20 C8               GET CONFIGURATION
05 1B                   GET_VWIRE
21 00 30 B8               GET CONFIGURATION
22 00 30 00 01 00 00 25       SET CONFIGURATION
22 00 08 03 00 20 00 95       SET CONFIGURATION
22 00 20 01 00 07 00 01       SET CONFIGURATION
22 00 30 00 01 00 00 25       SET CONFIGURATION
21 00 40 EF               GET CONFIGURATION
22 00 40 0C 11 00 00 F1       SET CONFIGURATION
04 03 02 70 03 30 41 BA 42 30 11 PUT_VWIRE
04 01 43 F0 44 F0 DA         PUT_VWIRE
04 03 02 70 03 30 41 BB 42 30 7A PUT_VWIRE
25 FB                   GET_STATUS
05 1B                   GET_VWIRE
04 03 02 70 03 30 41 B9 42 30 AC PUT_VWIRE
04 03 02 74 03 30 41 B9 42 30 D9 PUT_VWIRE
04 03 02 76 03 30 41 B9 42 30 60 PUT_VWIRE
04 03 02 77 03 30 41 B9 42 30 BF PUT_VWIRE
04 03 02 77 03 30 41 B9 42 32 B1 PUT_VWIRE
04 03 02 77 03 31 41 B9 42 32 D3 PUT_VWIRE
21 00 10 58               GET CONFIGURATION
04 03 02 77 03 33 41 B9 42 32 17 PUT_VWIRE
21 00 10 58               GET CONFIGURATION
22 00 10 01 11 00 00 F5       SET CONFIGURATION
45 00 80 15 9B F0           IOWR   
                      160 other Port 80h I/O writes
21 00 10 58               GET CONFIGURATION
22 00 10 17 11 00 00 E6       SET CONFIGURATION
21 00 10 58               GET CONFIGURATION
4F FE 0B 00 00 78 56 34 12 FF   PUT_MEMWR32_SHORT

 

The Agent is responding always with ACCEPT. But always before the ACCEPT response 16 WAIT_STATE are sent by Agent. We detected this issue with oscilloscope and with Intel Quartus SignalTap.

 

Regards

Wolfram

 

hareesh
Employee
362 Views

Hi,

i also working on this issue. just for conformation can you please share your platform design file or screenshot


WFitt
Novice
331 Views

Hi,

In the attachment you can find two screenshots.

The first is showing a GET_CONFIGURATION command:

21 00 08 10

The Agent Core is answering after 16 WAIT_STATEs

 

The second attachment is showing a PUT_MEMWR32_SHORT command

FE 0B 00 00 78 56 34 12 FF

The Agent Core is answering after 16 WAIT_STATES also.

 

 

hareesh
Employee
319 Views

Hi,

please check bellow attachment. actually wait state value configure by Master please check that

Screenshot 2022-12-20 062118.png

 

WFitt
Novice
305 Views

Hi,

bits 15:12 of the General Capabilities and Configurations Register is set to the default value 0000b by the master. This means: Maximum 16 Waite States allowed.

But this does not mean that the slave has to use 16 Wait States for every (!) response, even for simple accesses like GET_CONFIGURATION.

But the Intel eSPI Agent core does exactly this!

 

Kind Regards

Wolfram

 

hareesh
Employee
248 Views

i am debugging that just give me some time.


hareesh
Employee
196 Views

Hi,

please share you eSPI ip configuration details. like bellow attached one

 

 

Screenshot 2022-12-30 063238.png

 

i seen 3 cases related to eSPI from you. are you using same ip configuration for all cases for different. if different please share all cases configuration details. 

 

WFitt
Novice
169 Views

Hi,

I wish you a happy new year!

 

I am using the same configuration for all cases:

 

WFitt_0-1672649391244.png

 

Regards

Wolfram

hareesh
Employee
104 Views

Hi,

may how you are testing this?

if you are testing on modelsim or questasim pls share project file.

or else share how your testing processing.



Thank you,


hareesh
Employee
50 Views

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