On Mon, Mar 21, 2022 at 8:10 PM Rob Herring [off-list ref] wrote:

quoted

+properties:
+  compatible:
+    description: One compatible per product using this chip. Each product
+      need deliberate custom values for things such as LRA resonance
+      frequency and these are not stored in the device tree, rather we
+      let the operating system look up the appropriate parameters from a
+      table.
+    enum:
+      - immersion,isa1200-janice
+      - immersion,isa1200-gavini

Same device, different boards. I think I would put necessary properties
in the DT.

That will be all of these (from the driver):

+struct isa1200_config {
+       u8 ldo_voltage;
+       bool pwm_in;
+       bool erm;
+       u8 clkdiv;
+       u8 plldiv;
+       u8 freq;
+       u8 duty;
+       u8 period;
+};

Example:

+/* Configuration for Janice, Samsung Galaxy S Advance GT-I9070 */
+static const struct isa1200_config isa1200_janice = {
+       .ldo_voltage = ISA1200_LDO_VOLTAGE_30V,
+       .pwm_in = false,
+       .clkdiv = ISA1200_HCTRL0_DIV_256,
+       .plldiv = 2,
+       .freq = 0,
+       .duty = 0x3b,
+       .period = 0x77,
+};

This is derived from the compatible rather than individual properties
or extra regulator and/or clock abstractions in line with:
Documentation/devicetree/bindings/display/panel/ilitek,ili9322.yaml

Which was originally looking like so:
https://lore.kernel.org/dri-devel/20170813114448.20179-2-linus.walleij@linaro.org/ (local)

To which you replied:
https://lore.kernel.org/dri-devel/20170817204424.e2wdkmyp4vyx2qj3@rob-hp-laptop/ (local)

"Normally, we the physical panel is described which would imply all these
settings. Are there lots of panels with this controller that would
justify all these settings?"

In that case there was one (1)

In this case there are two (2) products that I know of. It does not have the
relationship between panel and panel controller products though, but...
it's not very different.

I don't think this chip was used a lot, I really tried to find other instances.
But they could exist of course.

If you are certain you want all of these in the device tree instead, I can
fix it of course, then I also want to know if e.g. regulator framework should
be employed for the (internal) LDO and clock framework for the internal
PLL divider so I don't have to rewrite the whole thing again.

Yours,
Linus Walleij