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[1/2] dt-bindings: HID: i2c-hid: elan: Introduce bindings for Elan eKTH6915

Message ID 20220519155925.1.Iedc61f9ef220a89af6a031200a7850a27a440134@changeid (mailing list archive)
State Superseded
Headers show
Series [1/2] dt-bindings: HID: i2c-hid: elan: Introduce bindings for Elan eKTH6915 | expand

Commit Message

Doug Anderson May 19, 2022, 11 p.m. UTC
Like many i2c-hid touchscreen controllers, the Elan eKTH6915
controller has a reset gpio. For the Goodix GT7375P touchscreen the
decision was to add a new binding rather than trying to add a new GPIO
to the existing i2c-hid binding. We'll follow the lead and do it here,
too.

SIDE NOTE: the Elan eKTH6915 is a touchscreen _controller_ that's
included as a part on some touchscreens. The reset line isn't truly
necessary for the functioning of the touchscreen, so it's possible
that some designs won't have it hooked up and will just guarantee the
power sequencing requirements with RLC circuits. Thus, we'll mark the
reset gpio as optional.

Note that if the reset GPIO isn't used there's actually no true need
to use the "elan,ekth6915" compatible instead of the "hid-over-i2c" on
Linux. However:
- Officially using just "hid-over-i2c" for this device violates the
  existing "hid-over-i2c" bindings. The bindings say that you're not
  supposed to use "post-power-on-delay-ms" without specifying a more
  specific compatible. Currently the Linux driver doesn't enforce
  this, but it violates the bindings to just use
  "hid-over-i2c". ...and if you're going to add a more specific
  compatible anyway, might as well do it right.
- Using this compatible means we don't need to specify
  "hid-descr-addr" since it's inferred from the compatible.
- Using this compatible means that the regulator names match the names
  on the Elan datasheet (vcc33 / vccio) vs the generic hid-over-i2c
  (vdd / vddl).

Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

 .../bindings/input/elan,ekth6915.yaml         | 65 +++++++++++++++++++
 1 file changed, 65 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/elan,ekth6915.yaml

Comments

Dmitry Torokhov May 22, 2022, 9:32 p.m. UTC | #1
On Thu, May 19, 2022 at 04:00:02PM -0700, Douglas Anderson wrote:
> Like many i2c-hid touchscreen controllers, the Elan eKTH6915
> controller has a reset gpio. For the Goodix GT7375P touchscreen the
> decision was to add a new binding rather than trying to add a new GPIO
> to the existing i2c-hid binding. We'll follow the lead and do it here,
> too.
> 
> SIDE NOTE: the Elan eKTH6915 is a touchscreen _controller_ that's
> included as a part on some touchscreens. The reset line isn't truly
> necessary for the functioning of the touchscreen, so it's possible
> that some designs won't have it hooked up and will just guarantee the
> power sequencing requirements with RLC circuits. Thus, we'll mark the
> reset gpio as optional.
> 
> Note that if the reset GPIO isn't used there's actually no true need
> to use the "elan,ekth6915" compatible instead of the "hid-over-i2c" on
> Linux. However:
> - Officially using just "hid-over-i2c" for this device violates the
>   existing "hid-over-i2c" bindings. The bindings say that you're not
>   supposed to use "post-power-on-delay-ms" without specifying a more
>   specific compatible. Currently the Linux driver doesn't enforce
>   this, but it violates the bindings to just use
>   "hid-over-i2c". ...and if you're going to add a more specific
>   compatible anyway, might as well do it right.
> - Using this compatible means we don't need to specify
>   "hid-descr-addr" since it's inferred from the compatible.
> - Using this compatible means that the regulator names match the names
>   on the Elan datasheet (vcc33 / vccio) vs the generic hid-over-i2c
>   (vdd / vddl).
> 
> Signed-off-by: Douglas Anderson <dianders@chromium.org>

Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Thanks.
diff mbox series

Patch

diff --git a/Documentation/devicetree/bindings/input/elan,ekth6915.yaml b/Documentation/devicetree/bindings/input/elan,ekth6915.yaml
new file mode 100644
index 000000000000..05e6f2df604c
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/elan,ekth6915.yaml
@@ -0,0 +1,65 @@ 
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/input/elan,ekth6915.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Elan eKTH6915 touchscreen controller
+
+maintainers:
+  - Douglas Anderson <dianders@chromium.org>
+
+description:
+  Supports the Elan eKTH6915 touchscreen controller.
+  This touchscreen controller uses the i2c-hid protocol with a reset GPIO.
+
+properties:
+  compatible:
+    items:
+      - const: elan,ekth6915
+
+  reg:
+    const: 0x10
+
+  interrupts:
+    maxItems: 1
+
+  reset-gpios:
+    description: Reset GPIO; not all touchscreens using eKTH6915 hook this up.
+
+  vcc33-supply:
+    description: The 3.3V supply to the touchscreen.
+
+  vccio-supply:
+    description:
+      The IO supply to the touchscreen. Need not be specified if this is the
+      same as the 3.3V supply.
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - vcc33-supply
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      ap_ts: touchscreen@10 {
+        compatible = "elan,ekth6915";
+        reg = <0x10>;
+
+        interrupt-parent = <&tlmm>;
+        interrupts = <9 IRQ_TYPE_LEVEL_LOW>;
+
+        reset-gpios = <&tlmm 8 GPIO_ACTIVE_LOW>;
+        vcc33-supply = <&pp3300_ts>;
+      };
+    };