Re: [PATCH 4/4] dts: iot2050: Support IOT2050-SM variant

[Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>]

On 19/12/2023 10:03, Jan Kiszka wrote:
> On 19.12.23 09:48, Krzysztof Kozlowski wrote:
>> On 19/12/2023 09:22, Jan Kiszka wrote:
>>>>
>>>>> +			gpios = <&wkup_gpio0 53 GPIO_ACTIVE_HIGH>;
>>>>
>>>> Ditto
>>>>
>>>
>>> This is adjusting the existing LED nodes in k3-am65-iot2050-common.dtsi,
>>> not introducing new ones. We can add the color properties in a separate
>>
>>
>> Then why aren't you overriding by phandle/label?
>>
> 
> We could do that as well if we added labels first (they don't exist so 
> far). Not seeing any difference, though.
> 
>>> patch, but the node names are now part of the kernel ABI. Changing them
>>> would break existing userland.
>>
>> You mean label. Why node names became the ABI? Which interface exposes them?
> 
> root@iot2050-debian:~# ls -l /sys/class/leds/


> total 0
> lrwxrwxrwx 1 root root 0 Dec 19 08:55 mmc0:: -> ../../devices/platform/bus@100000/4fa0000.mmc/leds/mmc0::
> lrwxrwxrwx 1 root root 0 Dec 19 08:55 mmc1:: -> ../../devices/platform/bus@100000/4f80000.mmc/leds/mmc1::
> lrwxrwxrwx 1 root root 0 Dec 14 21:12 status-led-green -> ../../devices/platform/leds/leds/status-led-green
> lrwxrwxrwx 1 root root 0 Dec 19 08:55 status-led-red -> ../../devices/platform/leds/leds/status-led-red
> lrwxrwxrwx 1 root root 0 Dec 19 08:55 user-led1-green -> ../../devices/platform/leds/leds/user-led1-green
> lrwxrwxrwx 1 root root 0 Dec 19 08:55 user-led1-red -> ../../devices/platform/leds/leds/user-led1-red
> lrwxrwxrwx 1 root root 0 Dec 19 08:55 user-led2-green -> ../../devices/platform/leds/leds/user-led2-green
> lrwxrwxrwx 1 root root 0 Dec 19 08:55 user-led2-red -> ../../devices/platform/leds/leds/user-led2-red
> 
>>>>> +
>>>>> +&dwc3_0 {
>>>>> +	assigned-clock-parents = <&k3_clks 151 4>,  /* set REF_CLK to 20MHz i.e. PER0_PLL/48 */
>>>>> +				 <&k3_clks 151 9>;  /* set PIPE3_TXB_CLK to CLK_12M_RC/256 (for HS only) */
>>>>> +	/delete-property/ phys;
>>>>> +	/delete-property/ phy-names;
>>>>
>>>> If your board need to remove phys from the SoC node, something is wrong.
>>>> Either your board or SoC.
>>>>
>>>> Any removal of properties in DTS is weird and unexpected. It deserves
>>>> comments.
>>>
>>> This goes along disabling USB3 which is by default enabled via
>>> k3-am65-iot2050-common-pg2.dtsi
>>
>> Isn't this mistake? Common part enables only these pieces which are
>> working in common hardware SoM. If your common part of hardware, which
>> DTSI should represent, has USB3 then why is it being disabled here? If
>> common hardware design does not have USB3, then why is it being enabled
>> in DTSI?
> 
> It's a trade-off between adding yet another dtsi for those widely 
> common bits vs. adjusting the differences of only one variant from 

You don't need to add one more DTSI to achieve proper architecture of
DTS/DTSI split.

> that. We do the same for the Display Port so far.

DTSI represents common piece of hardware, like SoM or re-usable blocks,
not trade-off.

Best regards,
Krzysztof