[PATCH v5 1/2] dt-bindings: PCI: rockchip,rk3399-pcie: Add PERST# inactive delay properties

[Enrique Hernández Bello]

The driver holds PERST# asserted for T_PVPERL (100 ms) before releasing it.
Endpoints disagree about what they want there: some need longer than the
default to settle, while others stop answering configuration reads when the
reset pulse is stretched that far, because PERST# stays asserted for the
whole wait.

Describe two properties so a board can state what its endpoint needs, named
after the ones the Rockchip vendor driver already uses for the dwc-based
controllers:

  rockchip,perst-inactive-ms      - the delay used at probe
  rockchip,s2r-perst-inactive-ms  - the delay used when resuming

Both are optional and the defaults preserve the current behaviour.

Signed-off-by: Enrique Hernández Bello <ehbello at gmail.com>
---
 .../bindings/pci/rockchip,rk3399-pcie.yaml        | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/Documentation/devicetree/bindings/pci/rockchip,rk3399-pcie.yaml b/Documentation/devicetree/bindings/pci/rockchip,rk3399-pcie.yaml
index 720a5f9..7ac915c 100644
--- a/Documentation/devicetree/bindings/pci/rockchip,rk3399-pcie.yaml
+++ b/Documentation/devicetree/bindings/pci/rockchip,rk3399-pcie.yaml
@@ -40,6 +40,21 @@ properties:
     maxItems: 1
     description: pre-reset GPIO
 
+  rockchip,perst-inactive-ms:
+    default: 100
+    description:
+      Time PERST# is held asserted before it is released, which is also the
+      width of the reset pulse. The default meets T_PVPERL for a slot that
+      is powered at the moment PERST# is asserted. Some endpoints need more
+      settling time than that, while others stop responding when the pulse
+      is that long. A value of 0 selects the 100 us minimum the PCI Express
+      CEM specification sets for the pulse.
+
+  rockchip,s2r-perst-inactive-ms:
+    description:
+      The same time, applied when resuming from system suspend. Defaults to
+      the value of rockchip,perst-inactive-ms.
+
   vpcie12v-supply:
     description: The 12v regulator to use for PCIe.
 
-- 
2.56.0