bsa-acs : Update arm_bsa_testcase_checklist.md and create tests for PCI_IN_06, PCI_IN_07, PCI_IN_08, PCI_IN_09, PCI_MM_02, as they can be covered by other equivalent ACS tests

[sunnywang-arm]

Rule language in BSA spec:

• RPCI_IN_06 PHB, in conjunction with Root Port, must recognize transactions that are coming in from application PEs as PCIe configuration transactions if the transaction address is within the ECAM range mapped to the Root Port,　or the hierarchy that originates at that Root Port. This must be done by mapping the address of the incoming memory transaction to the PCIe Configuration address space, as described in Table 26 (See Section 7.2.2 [1]).
• RPCI_IN_07 PHB in conjunction with Root Port must return all 1s as read response data for Configuration read requests to　non-existent functions and devices on the root bus, that is the primary bus of the Root Port. No error must be　reported to software by the Root Port unless explicitly enabled to do so (See Section 2.3.2 [1]).
• RPCI_IN_08 PHB, in conjunction with Root Port, must return all 1s as read response data for Configuration read requests　that get an unsupported request response from downstream Endpoints or switches. No error must be reported to software by the Root Port unless explicitly enabled to do so (See Section 2.3.2 [1])
• RPCI_IN_09 PHB in conjunction with Root Port must return all 1s as read response data for Configuration read requests　that arrive at the Root Port targeting downstream functions when the Root port link is in DL_Down status　(See Section 2.9.1 [1]). Note that this includes the case when the link is in L3 and the downstream device is　in D3cold. No error must be reported to software by the Root Port unless explicitly enabled to do so (See Section 2.3.2 [1])
• RPCI_MM_02 All systems must support mapping PCI Express memory space as non-cacheable memory

Comments from @gowthamsiddarthd:

• PCI_IN_06 - BSA PCIe enumeration and Linux enumeration both validate correct discovery of hierarchy. ACS already exercises standard enumeration flows via PCIe tests (e.g., p0xx series). No additional ACS test required.
• PCI_IN_07 - Overlaps with coverage intent of PCI_IN_16. Sufficiently covered
• PCI_IN_08 - BSA enumeration logic includes config reads to non-populated BDFs. Expected behavior (UR → read returns all 1’s) is already exercised as part of enumeration checks. Behavior validated implicitly
• PCI_IN_09 - PCI_ER_05, PCI_ER_06 validate DPC handling. These tests verify config access returning ~0 during link down.  Fully covered via existing error handling tests
• PCI_MM_02 - ACS test: test_pool/pcie/p094.c, Validates PCIe MMIO regions mapped as Device-nGnRnE / Non-cacheable.

[sunnywang-arm]

Comments from @chetan-rathore

• For the rules PCI_IN_06, PCI_IN_07 and PCI_IN_08 a manual review of devices discovered by ACS enumeration with actual system pcie topology will be fine, these rules implicitly are verified for sample device like exerciser, but that not ensure if these rules are followed by all the devices in the system.
• For PCI_IN_09, the PCI_ER_05 and PCI_ER_06 tests does not explicitly check if device is returning all 1s after link down, we can explore to leverage the PCI_ER_06 logic to have a explicit test for the rule.
• For PCI_MM_02 query, yes the linux test pcie/p094.c and exerciser test exerciser/e039.c which covers PCI_MM_03 also covers PCI_MM_02 as they map memory to NORMAL_NC.

[sunnywang-arm]

My comments:

• PCI_IN_06 is sufficiently validated through enumeration behavior. We need to update arm_bsa_testcase_checklist.md and test for it.
• PCI_IN_07 and PCI_IN_08 are just partially exercised implicitly. They are testable, and we need to implement new test cases for them. PCI_IN_08 test may require exerciser support
• PCI_IN_09 requires explicit test enhancement to validate behavior under link-down conditions. This is testable. we need to implement a new test case for it.
• PCI_MM_02 is covered by existing ACS test implementations. We need to update arm_bsa_testcase_checklist.md and test for it.