Re: [PATCH 7/9] ARM: dts: stm32: add Hardware debug port (HDP) on stm32mp25

On 2/26/25 16:30, Alexandre TORGUE wrote:

On 2/26/25 16:08, Krzysztof Kozlowski wrote:

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On 26/02/2025 10:33, Alexandre TORGUE wrote:

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+        hdp: pinctrl@44090000 {
+            compatible = "st,stm32mp-hdp";

So here again - you have stm32mp251 SoC, but use entirely different
compatible.

Ok so I will use "st,stm32mp15-hdp"

This means this is stm32mp15 SoC. I do not see such SoC on list of your
SoCs in bindings. What's more, there are no bindings for other SoC
components for stm32mp15!

Yes stm32mp15 is not a "real SoC". I agree that at the beginning of the
STM32 story we didn't have a clear rule/view to correctly naming our
compatible. We tried to improve the situation to avoid compatible like
"st,stm32", "st,stm32mp" or "st,stm32mp1". So we introduced
"st,stm32mp13", "st,stm32mp15" or "st,stm32mp25" for new drivers. So yes
it represents a SoC family and not a real SoC. We haven't had much
negative feedback it.

But, if it's not clean to do it in this way, lets define SoC compatible
for any new driver.

Compatibles are for hardware.

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For the HDP case it is: "st,stm32mp157" and used for STM32MP13,
STM32MP15 end STM32MP25 SoC families (if driver is the same for all
those SoCs).

No, it's three compatibles, because you have three SoCs. BTW, writing
bindings (and online resources and previous reviews and my talks) are
saying that, so we do not ask for anything new here, anything different.
At least not new when looking at last 5 years, because 10 years ago many
rules were relaxed...

So adding 3 times the same IP in 3 different SoCs implies to have 3 
different compatibles. So each time we use this same IP in a new SoC, we 
have to add a new compatible. My (wrong) understanding was: as we have 
the same IP (same hardware) in each SoC we have the same compatible (and 
IP integration differences (clocks, interrupts) are handled by DT 
properties.

Just to complete, reading the Linux kernel doc, as device are same we 
will use fallbacks like this:

MP15: compatible = "st,stm32mp151-hdp";
MP13: compatible = "st,stm32mp131-hdp", "st,stm32mp151-hdp";
MP25: compatible = "st,stm32mp251-hdp", "st,stm32mp151-hdp";

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Best regards,
Krzysztof