Rob Herring wrote: > On Mon, Jul 20, 2020 at 11:01 PM Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx> wrote: >> Rob Herring wrote: >>> On Thu, Jul 16, 2020 at 02:59:08PM -0700, Thinh Nguyen wrote: >>>> Introduce num-lanes and lane-speed-mantissa-gbps for devices operating >>>> in super-speed-plus. DWC_usb32 IP supports multiple lanes and can >>>> operate in different sublink speeds. Currently the device controller >>>> does not have the information of the phy's number of lanes supported. As >>>> a result, the user can specify them through these properties if they are >>>> different than the default setting. >>>> >>>> Signed-off-by: Thinh Nguyen <thinhn@xxxxxxxxxxxx> >>>> --- >>>> Documentation/devicetree/bindings/usb/dwc3.txt | 9 +++++++++ >>>> 1 file changed, 9 insertions(+) >>>> >>>> diff --git a/Documentation/devicetree/bindings/usb/dwc3.txt b/Documentation/devicetree/bindings/usb/dwc3.txt >>>> index d03edf9d3935..4eba0615562f 100644 >>>> --- a/Documentation/devicetree/bindings/usb/dwc3.txt >>>> +++ b/Documentation/devicetree/bindings/usb/dwc3.txt >>>> @@ -86,6 +86,15 @@ Optional properties: >>>> - snps,quirk-frame-length-adjustment: Value for GFLADJ_30MHZ field of GFLADJ >>>> register for post-silicon frame length adjustment when the >>>> fladj_30mhz_sdbnd signal is invalid or incorrect. >>>> + - snps,num-lanes: set to specify the number of lanes to use. Valid inputs are >>>> + 1 or 2. Apply if the maximum-speed is super-speed-plus >>>> + only. Default value is 2 for DWC_usb32. For DWC_usb31, >>>> + it is always 1 at super-speed-plus. >>>> + - snps,lane-speed-mantissa-gbps: set to specify the symmetric lane speed >>>> + mantissa in Gbps. Valid inputs are 5 or 10. Apply if >>>> + the maximum-speed is super-speed-plus only. Default >>>> + value is 10. For DWC_usb31, it's always 10 at >>>> + super-speed-plus. >>> This is all common USB things and should be common properties (which we >>> may already have). >> Sure. For "num-lanes" is simple, any objection if we use >> "lane-speed-mantissa-gbps"? Or should we add "lane-speed-exponent"? > 'num-lanes' is good as that's what PCIe uses. Document that with > 'maximum-speed'. > > I think 'super-speed-plus' should mean gen 2 10G per lane. Then > between num-lanes and maximum-speed you can define all 4 possible > rates. That may confuse the user because now we'd use 'super-speed-plus' to define the speed of the lane rather than the device itself. According to the USB 3.2 spec, super-speed-plus can mean gen2x1, gen1x2, or gen2x2. BR, Thinh
