Hi Felipe, On 11/7/2018 11:17 PM, Felipe Balbi wrote: > Hi, > > Thinh Nguyen <thinh.nguyen@xxxxxxxxxxxx> writes: >>>>>> diff --git a/Documentation/devicetree/bindings/usb/dwc3.txt b/Documentation/devicetree/bindings/usb/dwc3.txt >>>>>> index 636630fb92d7..712b344c3a31 100644 >>>>>> --- a/Documentation/devicetree/bindings/usb/dwc3.txt >>>>>> +++ b/Documentation/devicetree/bindings/usb/dwc3.txt >>>>>> @@ -95,6 +95,24 @@ Optional properties: >>>>>> this and tx-thr-num-pkt-prd to a valid, non-zero value >>>>>> 1-16 (DWC_usb31 programming guide section 1.2.3) to >>>>>> enable periodic ESS TX threshold. >>>>>> + - snps,refclk-period-ns: set to program the reference clock period. The valid >>>>>> + input periods are as follow: >>>>>> + +-------------+-----------------+ >>>>>> + | Period (ns) | Freq (MHz) | >>>>>> + +-------------+-----------------+ >>>>>> + | 25 | 39.7/40 | >>>>>> + | 41 | 24.4 | >>>>>> + | 50 | 20 | >>>>>> + | 52 | 19.2 | >>>>>> + | 58 | 17.2 | >>>>>> + | 62 | 16.1 | >>>>>> + +-------------+-----------------+ >>>>>> + - snps,enable-refclk-lpm: set to enable low power scheduling of isochronous >>>>>> + transfers by running SOF/ITP counters using the >>>>>> + reference clock. Only valid for DWC_usb31 peripheral >>>>>> + controller v1.80a and higher. Both >>>>>> + "snps,dis_u2_susphy_quirk" and >>>>>> + "snps,dis_enblslpm_quirk" must not be set. >>>>> sounds like you should rely on clk API here. Then on driver call >>>>> clk_get_rate() to computer whatever you need to compute. >>>>> >>>> There's nothing to compute here. We can simply enable this feature with >>>> "snps, enable-refclk-lpm" and the controller will use the default refclk >>>> settings. >>> Right, right. What I'm saying, though, is that we have a clock API for >>> describing a clock. So why wouldn't we rely on that API for this? I >>> think both of these new properties can be replaced with standard clock >>> API properties: >>> >>> clocks = <&clk1>, ..., <&lpm_clk> >>> clock-names = "clock1", ...., "lpm"; >>> >>> Then dwc3 core could, simply, check if we have a clock named "lpm" and >>> if there is, use NSECS_PER_SEC / clk_get_rate() to get its period and >>> write it to the register that needs the information. >> There's no new clock here. We are using the ref_clk for SOF and ITP >> counter for this feature. Also, clocks are optional on non-DT platforms. >> To use the clock API, then we need to update the driver to allow some >> optional clock such as "ref" clock for non-DT platforms. Do you want to >> do it like this? > I can't think of a problem that would arise from that. Can you? Mark, > Rob, what do you think? > No problem. That can be done. This will remove the "snps,refclk-period-ns" property. But we should have "snps,enable-refclk-lpm" to enable this feature. Thinh
