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C66x sRIO Port Link Timeout Configurations

Daisuke Maeda
Guru 20205 points

The equations of Port Link Timeout interval as follows:

 - Shortest: SRV_CLK * TIMEOUT_VALUE * 3
 - Longest: SRV_CLK * TIMEOUT_VALUE * 4

 NOTE: The SRV_CLK mean the Prescaled IP_CLK, where the Prescaled IP_CLK period = (IP_CLK period x PRESCALAR_SRV_CLK value).

Why is it that there are two equations, i.e. Shortest and Longest?

For the SP_LT_CTL.TIMEOUT_VALUE Field, in Row of the "value" in the Table 3-80, there are the eight values. Must these values be used?

Serial RapidIO (SRIO) for KeyStone Devices User's Guide (Rev. B)
http://www.ti.com/lit/ug/sprugw1b/sprugw1b.pdf
3.14.18 SP_LT_CTL

Best regards,

Daisuke

 

  • 0
    Guru 20205 points

    Hi,

    Please give me an answer as soon as possible.
    Your prompt reply would be appreciated.

    Best regards,

    Daisuke

     

  • 0
    TI__Genius 13235 points

    Hi Daisuke,

    I have found some additional information on this issue. I need to confer with a colleague on my findings and I will provide my feedback here. I will reply in about a day with my input.

    Thanks,

    Clinton

  • 0 in reply to Clinton Rodgers
    TI__Genius 13235 points

    Hi Daisuke,

    I wanted to give you an update. I'm still confirming the details of the port link timeout register. It will most likely be a couple days before I have more feedback. I'll post it here once I do.

    Thanks,

    Clinton

  • 0
    TI__Genius 13235 points

    Hi Daisuke,

    Daisuke Maeda said:
    Why is it that there are two equations, i.e. Shortest and Longest?

    The 2 equations provide a range for the timeout period for a selected timeout value. The actual timeout period for a port can vary between the calculated 'shortest' and 'longest' period.

    Daisuke Maeda said:
    For the SP_LT_CTL.TIMEOUT_VALUE Field, in Row of the "value" in the Table 3-80, there are the eight values. Must these values be used?

    No, you can use any value between 0x000000 and 0xFFFFFF, inclusive. As noted, a value of 0 will disable the timer. I will make sure that the documentation gets updated.

    Please let us know if you have any additional questions or comments.

    Thanks,

    Clinton

  • 0 in reply to Clinton Rodgers
    TI__Genius 13235 points

    Daisuke,

    I wanted to add some additional clarification. The actual time for the timeout can vary for each transaction between the calculated 'shortest' and 'longest' values. This is based on how the counter is implemented. This is compliant to the RapidIO standard.

    Thanks,

    Clinton

  • 0 in reply to Clinton Rodgers
    Guru 20205 points

    Hi Clinton,

    Thank you for your reply.

    Please let me confirm just in case. Is the actual timeout period to vary for each transaction not user-defined?

    Best regards,

    Daisuke

     

  • 0 in reply to Daisuke Maeda
    TI__Genius 13235 points

    Hi Daisuke,

    The timeout period is selected based on the prescaled IP_CLK and the user selected TIMEOUT_VALUE. However, that period can vary between the calculated 'shortest' and 'longest' values.

    Below I have provided an example of the 'shortest' and 'longest' values for the Port Link Timeout interval for a given prescaled IP_CLK configuration. This means that the actual timeout for one transaction could be 0.2976 uS and the next could be 0.3968 uS (or anything in between those 2 values).

    IP_CLK

    Frequency (MHz)

    IP_CLK

    Period (uS)

    RIO_IP_PRESCAL

    Prescaled

    IP_CLK

    period (uS)

    Port Link Timeout

    Shortest (uS)

    Port Link Timeout

    Longest (uS)

    312.5

    0.003

    31

    0.0992

    0.2976

    0.3968

    Let us know if this clarifies things or if you have any further questions.

    Thanks,

    Clinton

  • 0 in reply to Clinton Rodgers
    Guru 20205 points

    Hi Clinton,

    Thank you for your reply. I understand.

    Best regards,

    Daisuke