On Fri, 20 Aug 2021 18:00:21 +0200 Pali Rohár <pali@xxxxxxxxxx> wrote: > This property specifies slot power limit in mW unit. It is form-factor and > board specific value and must be initialized by hardware. > > Some PCIe controllers delegates this work to software to allow hardware > flexibility and therefore this property basically specifies what should > host bridge programs into PCIe Slot Capabilities registers. > > Property needs to be specified in mW unit, and not in special format > defined by Slot Capabilities (which encodes scaling factor or different > unit). Host drivers should convert value from mW unit to their format. > > Signed-off-by: Pali Rohár <pali@xxxxxxxxxx> > --- > Documentation/devicetree/bindings/pci/pci.txt | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/Documentation/devicetree/bindings/pci/pci.txt b/Documentation/devicetree/bindings/pci/pci.txt > index 6a8f2874a24d..e67d5db21514 100644 > --- a/Documentation/devicetree/bindings/pci/pci.txt > +++ b/Documentation/devicetree/bindings/pci/pci.txt > @@ -32,6 +32,12 @@ driver implementation may support the following properties: > root port to downstream device and host bridge drivers can do programming > which depends on CLKREQ signal existence. For example, programming root port > not to advertise ASPM L1 Sub-States support if there is no CLKREQ signal. > +- slot-power-limit: > + If present this property specifies slot power limit in mW unit. Host drivers > + can parse this slot power limit and use it for programming Root Port or host > + bridge, or for composing and sending PCIe Set_Slot_Power_Limit message > + through the Root Port or host bridge when transitioning PCIe link from a > + non-DL_Up Status to a DL_Up Status. > > PCI-PCI Bridge properties > ------------------------- SFP uses something similar for maximum power, but since the units are in milliwatt, the name of the property is maximum-power-milliwatt, to avoid problems. I think it should be done here as well, i.e. slot-maximum-power-milliwatt or maybe even maximum-power-milliwatt. Marek
