linux-kernel - Re: [PATCH] dt-bindings: clock: ti: Convert interface.txt to json-schema

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Date:   Tue, 28 Nov 2023 09:32:41 +0100
From:   Andreas Kemnade <andreas@...nade.info>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     mturquette@...libre.com, sboyd@...nel.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        kristo@...nel.org, linux-clk@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-omap@...r.kernel.org
Subject: Re: [PATCH] dt-bindings: clock: ti: Convert interface.txt to
 json-schema

On Tue, 28 Nov 2023 09:00:16 +0100
Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org> wrote:

> > +required:
> > +  - compatible
> > +  - clocks
> > +  - '#clock-cells'  
> 
> reg is required. Device cannot take "reg" from parent, DTS does not work
> like this.

Well, apparently they do... and I am just dealing with status quo and not
how it should be.
Look at commit 31fc1c63c2ae4a542e3c7ac572a10a59ece45c24
for the reasoning of not having reg.


well, look at drivers/clk/ti/clk.c
ti_clk_get_reg_addr();

...

       if (of_property_read_u32_index(node, "reg", index, &val)) {
                if (of_property_read_u32_index(node->parent, "reg",
                                               index, &val)) {
                        pr_err("%pOFn or parent must have reg[%d]!\n",
                               node, index);
                        return -EINVAL;
                }
        }


We have two usecases here (status quo in dts usage and code):
If these interface clocks are below a ti,clksel then we are describing 
multiple bits in the same register and therefore every child of ti,clksel
would have the same reg.
If the interface clock is not below a ti,clksel then we have reg.

Regards,
Andreas