Re: [PATCH V1 3/3] ASoC: codecs: Add aw87390 amplifier driver

[Linus Walleij]

On Mon, Sep 4, 2023 at 3:02 PM Krzysztof Kozlowski
<krzysztof.kozlowski@xxxxxxxxxx> wrote:
> On 04/09/2023 14:30, Mark Brown wrote:
> > On Mon, Sep 04, 2023 at 02:17:43PM +0200, Krzysztof Kozlowski wrote:
> >> On 04/09/2023 13:46, wangweidong.a@xxxxxxxxxx wrote:
> >
> >>> +   ret = regmap_read(regmap, AW87390_ID_REG, &chip_id);
> >>> +   if (ret) {
> >>> +           dev_err(&i2c->dev, "%s read chipid error. ret = %d\n", __func__, ret);
> >>> +           return ret;
> >>> +   }
> >
> >>> +   if (chip_id != AW87390_CHIP_ID) {
> >>> +           dev_err(&i2c->dev, "unsupported device\n");
> >
> >> Why? The compatible tells it cannot be anything else.
> >
> > This is very common good practice, as well as validating communication
>
> No, it is neither common nor good. The kernel's job is not to verify the
> supplied DTS. Rob also made here a point:
>
> https://lore.kernel.org/all/CAL_Jsq+wcrOjh7+0c=mrg+Qz6dbhOUE-VEeQ4FoWC3Y7ENoyfQ@xxxxxxxxxxxxxx/

I disagree, if a vendor one day decides to mount a new version of a
component without notifying the community or users this is really
helpful.

The function is named "probe()" for a reason, as in "inspect
the hardware and see what we find" this has always been the case
I think.

Yours,
Linus Walleij