linux-kernel - Re: [PATCH v2 0/7] usb: dwc3: Calculate REFCLKPER et. al. from reference clock

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Date:   Thu, 20 Jan 2022 12:29:32 +0200
From:   Baruch Siach <baruch@...s.co.il>
To:     Kathiravan T <kathirav@...eaurora.org>
Cc:     Sean Anderson <sean.anderson@...o.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, Felipe Balbi <balbi@...nel.org>,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Balaji Prakash J <bjagadee@...eaurora.org>,
        linux-kernel@...r.kernel.org,
        Robert Hancock <robert.hancock@...ian.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Michal Simek <michal.simek@...inx.com>,
        Rob Herring <robh+dt@...nel.org>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v2 0/7] usb: dwc3: Calculate REFCLKPER et. al. from
 reference clock

Hi Kathiravan,

On Thu, Jan 20 2022, Kathiravan T wrote:
> On 2022-01-19 23:44, Baruch Siach wrote:
>> Hi Sean,
>> On Tue, Jan 18 2022, Sean Anderson wrote:
>>> This is a rework of patches 3-5 of [1]. It attempts to correctly program
>>> REFCLKPER and REFCLK_FLADJ based on the reference clock frequency. Since
>>> we no longer need a special property duplicating this configuration,
>>> snps,ref-clock-period-ns is deprecated.
>>> Please test this! Patches 3/4 in this series have the effect of
>>> programming REFCLKPER and REFCLK_FLADJ on boards which already configure
>>> the "ref" clock. I have build tested, but not much else.
>> Tested here on IPQ6010 based system. USB still works. But the with 
>> "ref"
>> clock at 24MHz, period is calculated as 0x29. Previous
>> snps,ref-clock-period-ns value used to be 0x32.
>> Is that expected?
>
> Yes, it is 0x29 for IPQ60xx based SoCs. In downstream it was wrongly mentioned
> as 0x32, which was corrected recently.

Thanks for the update. This needs fixing in upstream kernel. I'll send a
patch.

For some reason USB appears to work here with both values. Is it because
I only use USB2 signals? If this is the case them I can not actually
test this series on my system.

Thanks,
baruch

>>> [1] 
>>> https://lore.kernel.org/linux-usb/20220114044230.2677283-1-robert.hancock@calian.com/
>>> Changes in v2:
>>> - Document clock members
>>> - Also program GFLADJ.240MHZDECR
>>> - Don't program GFLADJ if the version is < 2.50a
>>> - Add snps,ref-clock-frequency-hz property for ACPI
>>> Sean Anderson (7):
>>>   dt-bindings: usb: dwc3: Deprecate snps,ref-clock-period-ns
>>>   usb: dwc3: Get clocks individually
>>>   usb: dwc3: Calculate REFCLKPER based on reference clock
>>>   usb: dwc3: Program GFLADJ
>>>   usb: dwc3: Add snps,ref-clock-frequency-hz property for ACPI
>>>   arm64: dts: zynqmp: Move USB clocks to dwc3 node
>>>   arm64: dts: ipq6018: Use reference clock to set dwc3 period
>>>  .../devicetree/bindings/usb/snps,dwc3.yaml    |   7 +-
>>>  arch/arm64/boot/dts/qcom/ipq6018.dtsi         |   3 +-
>>>  .../arm64/boot/dts/xilinx/zynqmp-clk-ccf.dtsi |   4 +-
>>>  arch/arm64/boot/dts/xilinx/zynqmp.dtsi        |   4 +-
>>>  drivers/usb/dwc3/core.c                       | 112 +++++++++++++++---
>>>  drivers/usb/dwc3/core.h                       |  17 ++-
>>>  6 files changed, 120 insertions(+), 27 deletions(-)


-- 
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