Hi, Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx> writes: > 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. I agree. In USB land we should refer solely to the USB specification naming schemes. -- balbi
Attachment:
signature.asc
Description: PGP signature
