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? -- balbi
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