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

[Bjorn Andersson]

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@xxxxxxxxxxxxxxxx>
> > >>>> ---
> > >>>>  .../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.

Regards,
Bjorn

> > Kindly share your views
> 
> -- 
> With best wishes
> Dmitry