Re: [PATCH v2 2/4] dt-bindings: phy: qcom,msm8998-qmp-usb3-phy: Add support for Shikra

From: Krishna Kurapati <krishna.kurapati@oss.qualcomm.com>
To: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Neil Armstrong <neil.armstrong@linaro.org>,
	Vinod Koul <vkoul@kernel.org>, Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Bjorn Andersson <andersson@kernel.org>,
	Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>,
	Xiangxu Yin <xiangxu.yin@oss.qualcomm.com>,
	Johan Hovold <johan+linaro@kernel.org>,
	Loic Poulain <loic.poulain@oss.qualcomm.com>,
	Kathiravan Thirumoorthy
	<kathiravan.thirumoorthy@oss.qualcomm.com>,
	Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>,
	linux-arm-msm@vger.kernel.org, linux-phy@lists.infradead.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/4] dt-bindings: phy: qcom,msm8998-qmp-usb3-phy: Add support for Shikra
Date: Thu, 7 May 2026 17:07:33 +0530	[thread overview]
Message-ID: <d52c5039-9431-44ed-9f3b-bb00d03ae176@oss.qualcomm.com> (raw)
In-Reply-To: <40b5e0f6-bc61-4750-9560-bdcc268f0fe3@kernel.org>

On 5/5/2026 7:30 PM, Krzysztof Kozlowski wrote:
> On 05/05/2026 15:57, Krishna Kurapati wrote:
>>
>>
>> On 5/5/2026 6:59 PM, Krzysztof Kozlowski wrote:
>>> On 05/05/2026 15:27, Krishna Kurapati wrote:
>>>>
>>>>
>>>> On 5/5/2026 4:22 PM, Krzysztof Kozlowski wrote:
>>>>> On 05/05/2026 12:49, Krzysztof Kozlowski wrote:
>>>>>> On Mon, May 04, 2026 at 10:36:57PM +0530, Krishna Kurapati wrote:
>>>>>>> Declare the USB-C QMP PHY present on the Qualcomm Shikra platform.
>>>>>>>
>>>>>>> Signed-off-by: Krishna Kurapati <krishna.kurapati@oss.qualcomm.com>
>>>>>>> ---
>>>>>>>     .../devicetree/bindings/phy/qcom,msm8998-qmp-usb3-phy.yaml      | 2 ++
>>>>>>>     1 file changed, 2 insertions(+)
>>>>>>
>>>>>> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
>>>>>
>>>>> ... and then I looked at the driver. So un-reviewed. Devices are clearly
>>>>> compatible. If not, explain what is not compatible.
>>>>>
>>>> Talos uses GCC_USB3_PRIM_PHY_AUX_CLK.
>>>>
>>>> In Shikra, we are using GCC_USB3_PRIM_PHY_COM_AUX_CLK. We don't have
>>>> GCC_USB3_PRIM_PHY_AUX_CLK.
>>>>
>>>> Hence, I didn't use a fallback compatible.
>>>
>>> This still explains nothing. How different clock makes interface for SW
>>> incompatible exactly?
>>>
>> So I went by the naming. AUX vs COM_AUX.
> 
> The naming does not matter. If the clock is called
> "no_one_expects_spanish_inquisition", does that make software
> incompatible? Why would the name itself matter?
> 
>>
>> Can I use a fallback compatible and in DT vote for "COM_AUX" clock with
>> clock-names mentioning "aux" ?
> 
> I don't know, I asked what is different in software interface.
> 

Hi Krzysztof,

  I checked with the hw team here and found out two things.

  1. Shikra is a spinoff of Agatti and its sw interface (clocks used and 
regulators used) is the same as agatti.

  2. I thought we could use qcm2290 as a fallback since the phy register 
init sequence is the same for Talos/Shikra/Agatti. The difference 
between Talos and agatti when checked in the driver was the init load 
settings. I checked with the hw team and they suggested using the init 
load settings which talos was using.

  Hence both these compatibles (qcm2290 and qcs615) cannot be used as 
fallback for Shikra.

Regards,
Krishna,

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