From: Matthias Kaehlcke <mka@chromium.org>
To: Douglas Anderson <dianders@chromium.org>
Cc: Jiri Kosina <jikos@kernel.org>,
Benjamin Tissoires <benjamin.tissoires@redhat.com>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>,
Rob Herring <robh+dt@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
linux-input@vger.kernel.org, devicetree@vger.kernel.org,
swboyd@chromium.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/2] HID: i2c-hid: elan: Add support for Elan eKTH6915 i2c-hid touchscreens
Date: Mon, 23 May 2022 14:38:58 -0700 [thread overview]
Message-ID: <Yov+8u5Ohrzynlx9@google.com> (raw)
In-Reply-To: <20220523142257.v2.2.I2d3f735a485157eeaa24d60be8a327f98101789d@changeid>
On Mon, May 23, 2022 at 02:23:24PM -0700, Douglas Anderson wrote:
> Like many i2c-hid touchscreen controllers, the Elan eKTH6915 has a
> reset GPIO hooked up to it. According to the datasheet, the way we're
> supposed to turn the touchscreen on is:
>
> 1. Turn on the 3.3V supply.
> 2. Turn on the IO supply. It's OK if this is hardwired to the 3.3V
> supply, but if it's not then it must be turned on _after_ the 3.3V
> supply.
> 3. Wait >= 1 ms.
> 4. Deassert the reset GPIO (reset GPIO is active low, so there would
> be a leakage path if this was deasserted _before_ the IO supply).
> 5. Wait 300 ms.
>
> Much of the above can be handled by the generic i2c-hid-of driver, but
> the "reset" GPIO is not supported by that driver. Thus we'll do the
> same as we did for Goodix and add a new tiny driver that uses the
> i2c-hid core.
>
> NOTE: support for this new touchscreen could theorically fit into the
> Goodix driver. I've made it a separate driver because the Elan driver
> supports _two_ regulators and it's unclear exactly how that would fit
> in with commit 18eeef46d359 ("HID: i2c-hid: goodix: Tie the reset line
> to true state of the regulator").
>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
next prev parent reply other threads:[~2022-05-23 21:39 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-23 21:23 [PATCH v2 1/2] dt-bindings: HID: i2c-hid: elan: Introduce bindings for Elan eKTH6915 Douglas Anderson
2022-05-23 21:23 ` [PATCH v2 2/2] HID: i2c-hid: elan: Add support for Elan eKTH6915 i2c-hid touchscreens Douglas Anderson
2022-05-23 21:38 ` Matthias Kaehlcke [this message]
2022-05-23 23:35 ` [PATCH v2 1/2] dt-bindings: HID: i2c-hid: elan: Introduce bindings for Elan eKTH6915 Doug Anderson
2022-06-02 13:38 ` Rob Herring
2022-06-08 9:47 ` Jiri Kosina
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