linux-kernel - Re: [PATCH 2/5] arm64: dts: qcom: sdm845-db845c-navigation-mezzanine: fix ov7251 lane properties

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Message-ID: <cd754842-42f0-4938-b590-34ed7c4503c6@linaro.org>
Date: Wed, 4 Dec 2024 15:10:47 +0200
From: Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>
To: neil.armstrong@...aro.org, Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: Bjorn Andersson <andersson@...nel.org>,
 Konrad Dybcio <konradybcio@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, cros-qcom-dts-watchers@...omium.org,
 linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/5] arm64: dts: qcom: sdm845-db845c-navigation-mezzanine:
 fix ov7251 lane properties

On 12/4/24 14:16, Neil Armstrong wrote:
> On 04/12/2024 12:05, Dmitry Baryshkov wrote:
>> On Wed, Dec 04, 2024 at 11:56:54AM +0100, Neil Armstrong wrote:
>>> Bindings documents data-lanes as a single entry with a separate
>>> clock-lanes property, but DT uses 2 entries in data-lanes.
>>>
>>> This would suggest clock-lanes is missing, fix the DT using the
>>> bindings example.
>>>
>>> This fixes:
>>> sdm845-db845c-navigation-mezzanine.dtso: camera@60: port:endpoint:data-lanes: [0, 1] is too long
>>> 	from schema $id: http://devicetree.org/schemas/media/i2c/ovti,ov7251.yaml#
>>>
>>> Signed-off-by: Neil Armstrong <neil.armstrong@...aro.org>
>>> ---
>>>    arch/arm64/boot/dts/qcom/sdm845-db845c-navigation-mezzanine.dtso | 3 ++-
>>>    1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/arch/arm64/boot/dts/qcom/sdm845-db845c-navigation-mezzanine.dtso b/arch/arm64/boot/dts/qcom/sdm845-db845c-navigation-mezzanine.dtso
>>> index 0a87df806cafc8e726aacc07a772ca478d0ee3df..5a16f4c2b346b314af3d614266e1ca034057e643 100644
>>> --- a/arch/arm64/boot/dts/qcom/sdm845-db845c-navigation-mezzanine.dtso
>>> +++ b/arch/arm64/boot/dts/qcom/sdm845-db845c-navigation-mezzanine.dtso
>>> @@ -115,7 +115,8 @@ camera@60 {
>>>    
>>>    		port {
>>>    			ov7251_ep: endpoint {
>>> -				data-lanes = <0 1>;
>>> +				clock-lanes = <1>;
>>> +				data-lanes = <0>;
>>
>> Is it really this way or the other way around, clock = <0>, data = <1>?
> 
> No idea actually, on the schematics the lanes from the DB845 are :
> 
> CSI0_P/N -> OV7251_CSI3_LANE0_P/N -> MIPI_CSI3_LANE0_P -> SoC
> and
> CLKP/N -> OV7251_CSI3_CLK_P/N -> MIPI_CSI3_CLK_P/N -> SoC
> 
> So I assume the data-lane is 0, for clock-lane I just used
> the example, but I found nothing in the code using those assignments
> 

It's a sensor property, and OV7251 sensor has the non-selectable clock lane.

If it's technically acceptable, I would rather suggest to deprecate and
remove "clock-lanes" property and hard-code "data-lanes" value to <1>.

By the way, this particular device tree bindings miss bus-type property,
it could be either MIPI or LVDS serial output.

--
Best wishes,
Vladimir