Regarding "brcm,enable-l1ss":
The Broadcom STB/CM PCIe HW -- a core that is also used by RPi SOCs --
requires the driver probe() to deliberately place the HW one of three
CLKREQ# modes:
(a) CLKREQ# driven by the RC unconditionally
(b) CLKREQ# driven by the EP for ASPM L0s, L1
(c) Bidirectional CLKREQ#, as used for L1 Substates (L1SS).
The HW+driver can tell the difference between downstream devices that
need (a) and (b), but does not know when to configure (c). Further, the
HW may cause a CPU abort on boot if guesses wrong regarding the need for
(c). So we introduce the boolean "brcm,enable-l1ss" property to indicate
that (c) is desired. Setting this property only makes sense when the
downstream device is L1SS-capable and the OS is configured to activate
this mode (e.g. policy==superpowersave).
This property is already present in the Raspian version of Linux, but the
upstream driver implementaion that will follow adds more details and
discerns between (a) and (b).
Regarding "brcm,completion-timeout-us"
Our HW will cause a CPU abort if the L1SS exit time is longer than the
PCIe transaction completion abort timeout. We've been asked to make this
configurable, so we are introducing "brcm,completion-timeout-us".
Signed-off-by: Jim Quinlan <jim2101024@xxxxxxxxx>
---
.../devicetree/bindings/pci/brcm,stb-pcie.yaml | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/Documentation/devicetree/bindings/pci/brcm,stb-pcie.yaml b/Documentation/devicetree/bindings/pci/brcm,stb-pcie.yaml
index 7e15aae7d69e..f7fc2f6561bb 100644
--- a/Documentation/devicetree/bindings/pci/brcm,stb-pcie.yaml
+++ b/Documentation/devicetree/bindings/pci/brcm,stb-pcie.yaml
@@ -64,6 +64,22 @@ properties:
aspm-no-l0s: true
+ brcm,enable-l1ss:
+ description: Indicates that PCIe L1SS power savings
+ are desired, the downstream device is L1SS-capable, and the
+ OS has been configured to enable this mode. Note that when
+ in this mode, this particular HW may not meet the requirement
+ that requires CLKREQ# assertion to clock active to be
+ within 400ns.
+ type: boolean
+
+ brcm,completion-timeout-us:
+ description: Number of microseconds before PCI transaction
+ completion timeout abort is signalled.
+ minimum: 16
+ default: 1000000
+ maximum: 19884107
+
brcm,scb-sizes:
description: u64 giving the 64bit PCIe memory
viewport size of a memory controller. There may be up to
--
2.17.1
