[PATCH v2 00/10] PCI: tegra194: Fix EP and Root Port corner cases

[Manikanta Maddireddy <mmaddireddy@nvidia.com>]

This series fixes a set of independent Tegra194/Tegra234 PCIe controller
issues found while testing Root Port and Endpoint flows.

The Root Port fixes tighten probe/remove and suspend/resume error handling:
propagate optional GPIO failures, check reset deassertion, avoid skipping
cleanup when no link came up, and balance the optional core monitor clock
on failures.

The Endpoint fixes cover PERST# IRQ suspend handling, PHY/PLL error
unwinds, capability checks before programming optional PCIe extended
capabilities, hiding Tegra234 EP L1.2 advertisement for the documented
hardware limitation, and rejecting invalid MSI interrupt number zero.

The patches are ordered from low-level error handling toward Endpoint
capability checks and MSI validation. MSI-X enablement, MSI-X doorbell
changes and fixed MSI-X table handling are deferred; MSI-X remains
disabled in the Tegra EPC features.

Changes in v2:
- Expand the PERST# suspend-race explanation to describe how an IRQ thread
  can enable the endpoint after the original state check. Explain how
  disable_irq() drains that thread and preserves the existing suspend
  policy, and add a synchronization comment.
- Split the MSI-only zero check out of the former MSI/MSI-X patch, with a
  focused title and commit message. Treat it as defensive validation and
  omit the Fixes tag from that patch.
- Drop all MSI-X changes and the fixed MSI-X table patch (v1 patch 11),
  reducing the series from eleven patches to ten.
- Adapt register names to the preceding DWC register-field cleanup series.

Validation:
- ARM64 compilation of the Tegra driver passed.
- Checkpatch and whitespace checks passed.
- Tegra PCIe EP link up with pci-epf-test driver.
- pci_endpoint_test
  - pci_ep_bar.BAR0.BAR_TEST
  - pci_ep_basic.CONSECUTIVE_BAR_TEST
  - pci_ep_basic.LEGACY_IRQ_TEST
  - pci_ep_basic.MSI_TEST
  - pci_ep_data_transfer.memcpy.READ_TEST
  - pci_ep_data_transfer.memcpy.WRITE_TEST
  - pci_ep_data_transfer.memcpy.COPY_TEST

v1: https://lore.kernel.org/linux-pci/20260923072237.1139013-1-mmaddireddy@nvidia.com/

Manikanta Maddireddy (10):
  PCI: tegra194: Propagate REFCLK select GPIO errors
  PCI: tegra194: Check core reset deassertion
  PCI: tegra194: Fix Endpoint PERST# IRQ suspend race
  PCI: tegra194: Do not skip no-link Root Port remove cleanup
  PCI: tegra194: Check for 16 GT/s capability before programming
  PCI: tegra194: Check for L1SS capability before programming
  PCI: tegra194: Always disable Tegra234 Endpoint L1.2
  PCI: tegra194: Guard Endpoint PLL-off error path
  PCI: tegra194: Balance core monitor clock on failures
  PCI: tegra194: Reject zero MSI interrupt number

 drivers/pci/controller/dwc/pcie-tegra194.c | 221 +++++++++++++--------
 1 file changed, 142 insertions(+), 79 deletions(-)

-- 
2.34.1