linux-kernel - Re: [PATCH v2 1/5] dt-bindings: phy: cadence-torrent: Add optional input reference clock for PLL1

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Message-ID: <38d171ee-b94b-4d1c-8702-60735a005596@linaro.org>
Date:   Thu, 14 Dec 2023 08:22:12 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Swapnil Kashinath Jakhade <sjakhade@...ence.com>,
        "vkoul@...nel.org" <vkoul@...nel.org>,
        "kishon@...nel.org" <kishon@...nel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "conor+dt@...nel.org" <conor+dt@...nel.org>,
        "linux-phy@...ts.infradead.org" <linux-phy@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Cc:     Milind Parab <mparab@...ence.com>,
        "rogerq@...nel.org" <rogerq@...nel.org>,
        "s-vadapalli@...com" <s-vadapalli@...com>
Subject: Re: [PATCH v2 1/5] dt-bindings: phy: cadence-torrent: Add optional
 input reference clock for PLL1

On 14/12/2023 08:02, Swapnil Kashinath Jakhade wrote:
> Hi Krzysztof,
> 
>> -----Original Message-----
>> From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
>> Sent: Wednesday, December 13, 2023 12:19 PM
>> To: Swapnil Kashinath Jakhade <sjakhade@...ence.com>; vkoul@...nel.org;
>> kishon@...nel.org; robh+dt@...nel.org; krzysztof.kozlowski+dt@...aro.org;
>> conor+dt@...nel.org; linux-phy@...ts.infradead.org; linux-
>> kernel@...r.kernel.org; devicetree@...r.kernel.org
>> Cc: Milind Parab <mparab@...ence.com>; rogerq@...nel.org; s-
>> vadapalli@...com
>> Subject: Re: [PATCH v2 1/5] dt-bindings: phy: cadence-torrent: Add optional
>> input reference clock for PLL1
>>
>> EXTERNAL MAIL
>>
>>
>> On 12/12/2023 12:48, Swapnil Jakhade wrote:
>>> Torrent PHY can have two input reference clocks. Update bindings
>>
>> It already supports two.
>>
> 
> Thanks for your comments.
> refclk and pll1_refclk are the two input reference clocks for the PLLs.
> phy_en_refclk is used to enable output reference clock in some cases.

Why input clock is used to enable output reference clock?

> 
>>> to support dual reference clock multilink configurations.
>>>
>>> Signed-off-by: Swapnil Jakhade <sjakhade@...ence.com>
>>> ---
>>>  .../devicetree/bindings/phy/phy-cadence-torrent.yaml        | 6 +++---
>>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/Documentation/devicetree/bindings/phy/phy-cadence-
>> torrent.yaml b/Documentation/devicetree/bindings/phy/phy-cadence-
>> torrent.yaml
>>> index dfb31314face..98946f549895 100644
>>> --- a/Documentation/devicetree/bindings/phy/phy-cadence-torrent.yaml
>>> +++ b/Documentation/devicetree/bindings/phy/phy-cadence-torrent.yaml
>>> @@ -35,14 +35,14 @@ properties:
>>>      minItems: 1
>>>      maxItems: 2
>>>      description:
>>> -      PHY reference clock for 1 item. Must contain an entry in clock-names.
>>> -      Optional Parent to enable output reference clock.
>>> +      PHY input reference clocks - refclk & pll1_refclk (optional).
>>> +      Optional Parent to enable output reference clock (phy_en_refclk).
>>
>> So third clock? But you allow only two? Confusing.
>>
> 
> Yes, if both refclk and pll1_refclk are present, phy_en_refclk can't be used.
> 
>>>
>>>    clock-names:
>>>      minItems: 1
>>>      items:
>>>        - const: refclk
>>> -      - const: phy_en_refclk
>>> +      - enum: [ pll1_refclk, phy_en_refclk ]
>>
>> This does not match your commit msg. You already had two clocks there.
>>
> Yes, but refclk was the single input reference clock used for PLLs earlier.
> As stated in commit message, a new input reference clock (pll1_refclk) is added here.

existing phy_en_refclk is also input reference clock, isn't it?

> 

Best regards,
Krzysztof