On 06/04/2023 20:53, Florian Fainelli wrote: > On 4/6/23 11:34, Krzysztof Kozlowski wrote: >> On 06/04/2023 14:46, Jim Quinlan wrote: >>> Regarding "brcm,enable-l1ss": >>> >>> The Broadcom STB/CM PCIe HW -- which is also used by RPi SOCs -- requires >>> the driver probe to configure one of three clkreq# modes: >>> >>> (a) clkreq# driven by the RC >>> (b) clkreq# driven by the EP for ASPM L0s, L1 >>> (c) bidirectional clkreq#, as used for L1 Substates (L1SS). >>> >>> The HW can tell the difference between (a) and (b), but does not know >>> when to configure (c). Further, the HW will 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. This >>> property is already present in the Raspian version of Linux, but the >>> driver implementaion that will follow adds more details and discerns >>> between (a) and (b). >>> >>> Regarding "brcm,completion-timeout-msecs" >>> >>> Our HW will cause a CPU abort if the L1SS exit time is longer than the >>> completion abort timeout. We've been asked to make this configurable, so >>> we are introducing "brcm,completion-abort-msecs". >>> >>> Signed-off-by: Jim Quinlan <jim2101024@xxxxxxxxx> >>> --- >>> .../devicetree/bindings/pci/brcm,stb-pcie.yaml | 12 ++++++++++++ >>> 1 file changed, 12 insertions(+) >>> >>> diff --git a/Documentation/devicetree/bindings/pci/brcm,stb-pcie.yaml b/Documentation/devicetree/bindings/pci/brcm,stb-pcie.yaml >>> index 7e15aae7d69e..ef4ccc05b258 100644 >>> --- a/Documentation/devicetree/bindings/pci/brcm,stb-pcie.yaml >>> +++ b/Documentation/devicetree/bindings/pci/brcm,stb-pcie.yaml >>> @@ -64,6 +64,18 @@ properties: >>> >>> aspm-no-l0s: true >>> >>> + brcm,enable-l1ss: >>> + description: Indicates that the downstream device is L1SS >>> + capable and L1SS is desired, e.g. by setting >>> + CONFIG_PCIEASPM_POWER_SUPERSAVE=y. Note that CLKREQ# >> >> How does CONFIG_PCIEASPM_POWER_SUPERSAVE apply to *BSD? > > In other words, there should be no OS/Linux specific comments in a > Device Tree binding, which would be a friendlier and nicer way of > providing the same feedback. I want to give also the answer also why there should be no OS/Linux specific comments, so the reader can stop a bit and think about it :) Best regards, Krzysztof
