Re: [PATCH 1/2] arm64: dts: qcom: qcs6490-rb3gen2-industrial-mezzanine: Add model string

[Umang Chheda <umang.chheda@oss.qualcomm.com>]

Hello Bjorn, Dmitry,

On 3/26/2026 8:29 AM, Bjorn Andersson wrote:
> On Mon, Mar 23, 2026 at 09:06:54PM +0200, Dmitry Baryshkov wrote:
>> On Mon, Mar 23, 2026 at 10:33:45PM +0530, Umang Chheda wrote:
>>> Hello Dmitry,
>>>
>>> On 3/13/2026 11:23 PM, Dmitry Baryshkov wrote:
>>>> On Tue, Mar 10, 2026 at 02:09:58PM +0530, Umang Chheda wrote:
>>>>> Hello Dmitry,
>>>>>
>>>>> On 3/10/2026 2:07 AM, Dmitry Baryshkov wrote:
>>>>>> On Mon, Mar 09, 2026 at 05:49:35PM +0530, Umang Chheda wrote:
>>>>>>> The RB3 Gen2 Industrial mezzanine DT file lacks a "model" property,
>>>>>>> resulting in the hardware always being reported as the "Robotics RB3gen2".
>>>>>>> This prevents applications and user-space tooling from distinguishing
>>>>>>> the Industrial mezzanine Kit from other RB3Gen2 variants.
>>>>>>>
>>>>>>> To ensure consistent identification across all RB3 Gen2 mezzanines,
>>>>>>> add the appropriate model string.
>>>>>>>
>>>>>>> Signed-off-by: Umang Chheda <umang.chheda@oss.qualcomm.com>
>>>>>>> ---
>>>>>>>  .../boot/dts/qcom/qcs6490-rb3gen2-industrial-mezzanine.dtso   | 4 ++++
>>>>>>>  1 file changed, 4 insertions(+)
>>>>>>>
>>>>>>> diff --git a/arch/arm64/boot/dts/qcom/qcs6490-rb3gen2-industrial-mezzanine.dtso b/arch/arm64/boot/dts/qcom/qcs6490-rb3gen2-industrial-mezzanine.dtso
>>>>>>> index 619a42b5ef48..7d6e425dae89 100644
>>>>>>> --- a/arch/arm64/boot/dts/qcom/qcs6490-rb3gen2-industrial-mezzanine.dtso
>>>>>>> +++ b/arch/arm64/boot/dts/qcom/qcs6490-rb3gen2-industrial-mezzanine.dtso
>>>>>>> @@ -8,6 +8,10 @@
>>>>>>>  #include <dt-bindings/clock/qcom,gcc-sc7280.h>
>>>>>>>  #include <dt-bindings/pinctrl/qcom,pmic-gpio.h>
>>>>>>>
>>>>>>> +&{/} {
>>>>>>> +	model = "Qualcomm Technologies, Inc. QCS6490 RB3gen2 Industrial Mezzanine";
>>>>>> So, what happens if I combine Industrial and Vision mezzanines?
>>>>> H/W does not support to connect both Industrial and vision mezzanine at same time - only single mezzanine can be
>>>>>
>>>>> connected at a given point in time - hence probably the above scenario would never occur.
>>>> Industrial mezzanine has all LS and HS connectors, so it is possible to
>>>> stack Vision mezz on top of the industrial one.
>>>
>>> I re-checked - from f/w side as well multiple DTSO selection is not supported - and at a single point in time only single mezz can be selected
>>
>> What does this have to do with the firmware? From the Linux build system
>> point of view we are combining the overlay into a single
>> qcs6490-rb3gen2-industrial-mezzanine.dtb file.
>>
>> Nothing prevents me from writing:
>>
>> qcs6490-rb3gen2-multi-mezzanine-dtbs := qcs6490-rb3gen2.dtb \
>> 		qcs6490-rb3gen2-industrial-mezzanine.dtbo \
>> 		qcs6490-rb3gen2-vision-mezzanine.dtbo
>> dtb-$(CONFIG_ARCH_QCOM)        += qcs6490-rb3gen2-multi-mezzanine.dtb
>>
>>> considering above point - is it okay to have this patch ? I believe it would be good to have model string in the DTSO file added.
>>
>> No. A _mezzanine_ can not be a device model. It is by definition
>> something that you plug into the main device. Maybe creating something
>> new, a new kit.
>>
>> Moreover, the model name is not an ABI, we should not be using it for
>> device identification.
>>
> 
> I do agree.
> 
> That said, as we (others) discussed during LPC, it would be very useful
> for bug reporting purposes to know what overlays has been applied - or
> in general what "version" of the dtb we're running the system from.
> 
> I don't think "model" is what we're looking for there though.

Does adding something like below in the chosen node from the DTSO file
works good instead of a model string to identify the list of overlays
applied ?

&{/chosen} {
	applied-overlays {
		industrial-mezzanine {
			status = "okay";
		};
	};
};

> 
> Regards,
> Bjorn
> 
>>> Kindly share your views
>>
>> -- 
>> With best wishes
>> Dmitry

Thanks,
Umang