Hi, Thinh Nguyen <thinh.nguyen@xxxxxxxxxxxx> writes: >> 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. not really. Just check if you have a clock named lpm. If you do, then you enable the feature. -- balbi
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