PCI Express Certification  

 

 

PCI Express Compliance Test Overview

Passing PCI Express Compliance Program may seem like a daunting challenge for a first timer. While the PCI-SIG web site provides some details, there are still a lot of answers that can only be learned through experience. The following guide is designed to ease the procedure and ensure a first time success.

What is the PCI Express Compliance Program?

PCI Express Compliance Testing is provided by the PCI-SIG to ensure product compatibility across all platforms. To accomplish this goal, the PCI-SIG arranges multiple compliance workshops (Plugfests) each year. At these workshops, vendors for add-in cards, components, and systems all gather to test their products both against a set of standard tests, as well as with the devices from other companies.

What happens at these compliance workshops?

The compliance workshops themselves are very busy and last for an entire week. Vendor are required to sign up to attend the workshop. The deadline is generally a week or two before the actual workshop itself.

The Monday of the week long session consists of checking in, and listening to a few presentations regarding the latest events, specification updates, fixes, and an introduction to the remaining week's activity. All vendors are required to check in on Monday, as the testing schedules are produced based on the actual attendance (rather than the number signed up).

The testing schedules, which are given Tuesday morning, designates each vendor's testing periods during the workshop. At the workshop, each system (motherboard) vendor will be set up in a room, and the add-in cards vendor will go from room to room to visit with each of the system vendors. The schedule sets aside 1 hour session in which a system and a add-in card vendor can meet. If time permits, the parties may choose to meet longer or at a different time. Depending on the total number of vendors at each compliance workshop, there may be some gaps in the schedules. The organizer seems to be able to attract an equal number of system and add-in card vendor to each show to balance out each groups workload.

During each session, both parties simply need to verify that their product works with the other parties product. The definition of “works” is somewhat liberal. Since the goal of the workshop is to ensure bus compliance, PCI-SIG less concern with whether a vendor's product (e.g. PCI Express video card) perform as advertised than making sure that the product is PCI Express compliant. Vendors are expected to demonstrate minimal functionality of the devices to the satisfaction of both parties. The requirement for passing the interoperability portion of the compliance workshop is a 80% success rate with all the vendors that each product is tested with.

The 80% rate is designed to give a buffer so that a product is not unfairly punished for what may ultimately turn out to be the failure of the other party. Without the 20% buffer, just one non-compliant add-in card will fail all the motherboards that it is tested with, making every motherboard vendor fail its compliant test.

In the event of a failure, both parties are encouraged to work with each other to diagnose and solve the problems. The confidentiality of the test results are expected to be kept between both parties. To further ensure confidentiality, choosing to test with any specific vendor is completely optional. One common reason for choosing not to test is if both parties are competitors of each other. A vendor is still required to pass 80% of the remaining vendor products it tested with.

Oftentimes an individual session will not last the full hour. This usually happens if both vendors' product work correctly immediately. In this case, vendors will often try to visit as many other booths as they can. The first reason for this is that a vendor can squeeze in additional testing with vendors whom it may not have been scheduled with originally. Other reasons would be to finish early, thus leaving additional time for debugging when necessary, and/or to leave early!

Add-in card vendors should be aware that if they have any Friday (especially afternoon) sessions with a system vendor, they need to make sure that the system vendor does not check out before the session ends. In general reconfirming a Friday's schedule is a good practice.

What about the standard tests?

In addition to the interoperability tests between vendors, there will also be 3 standard testing sessions for add-in cards. These will be scheduled in 1 hour blocks like each vendor-to-vendor test, except that the tests are run by the PCI-SIG. The 3 tests are: Electrical Testing, Configuration Testing, and Link/Transaction Testing. Unlike the interoperability test, 100% success rate is required for all 3 standard tests.

The Electrical Testing will test the electrical characteristics and property of each card or motherboard. Jitter rate, voltage level, impedance, skew, etc. are tested. For the most part, the ability to pass this portion of the testing will be dependent on the PHY, and to a certain degree, board layout and placement.

The Configuration testing is performed using the PCI Express Configuration Test Software (PCIE-CV). This software is available for download from the PCI-SIG web site for PCI-SIG members. The software performs testing of the configuration registers. More information on the PCIE-CV can be found on the PCIE verification page.

The Link/Transaction testing utilize the Agilent E2969A Protocol Test Card. The main purpose of this test is to verify the proper behavior of the data link and transaction layers. More details on the PTC and it's tests can be found on the PCIE verification page.

What happens after the workshop is over?

After a device passes all the standard tests and demonstrates 80% interoperability or better, the next step is to submit the Compliance Checklist.

The Compliance Checklist is available from the PCI-SIG web site, and is an extremely detailed listing of design requirements and assertions that need to be met to be fully compliant. Not all of the requirements are tested at the compliance workshop, so the checklist provides an excellent “design time” and “design review” tool which compliment the actual testing at the plugfest.

After passing the compliance workshop and submitting the compliance checklist, the device will be listed on the Integrator's list within a few weeks!

When and where is the compliance workshop?

The PCI-SIG posts a list of upcoming workshops on its web site. In the past, most of the workshops were held in Milpitas, California, several times a year. Compliance workshop is also held in Taiwan. Recently, the PCI-SIG has implemented a new program, called the “PCIe Third Party Test Program.”

The Third Party Test Lab Program is designed to alleviate the growing demand for compliance testing. The Third Party Test Labs are independent companies that have been approved by the PCI-SIG to conduct compliance testing. The same standard tests are run, and the interoperability tests are achieved by having multiple off-the-shelf systems available. Currently, there is only one approved Third Party Test Lab located in Taiwan. The program may expand to include additional test labs in the future.

How can I learn more?

More information can be found on the PCI-SIG web site

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