[PATCH 0/2] Input: cros-ec-keyb: Don't register keyboard if doesn't exist

[PATCH 0/2] Input: cros-ec-keyb: Don't register keyboard if doesn't exist

[Stephen Boyd]

We're registering a keyboard input device on detachable chromebooks when
that input device doesn't generate any events. This patch series stops
doing that to save some runtime memory and to help userspace understand
that there really isn't a keyboard present when the keyboard is
detached. The second patch is an RFC because it should be picked up
through arm-soc tree, not input tree.

Stephen Boyd (2):
  Input: cros-ec-keyb: Only register keyboard if rows/columns exist
  arm64: dts: qcom: sc7180-trogdor: Remove cros-ec keyboard from
    detachables

 arch/arm64/boot/dts/qcom/sc7180-trogdor-coachz.dtsi   | 5 +++++
 arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar.dtsi | 5 +++++
 drivers/input/keyboard/cros_ec_keyb.c                 | 9 +++++++++
 3 files changed, 19 insertions(+)

Cc: Benson Leung <bleung@chromium.org>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Hsin-Yi Wang <hsinyi@chromium.org>

base-commit: 3123109284176b1532874591f7c81f3837bbdc17
-- 
https://chromeos.dev

[PATCH 1/2] Input: cros-ec-keyb: Only register keyboard if rows/columns exist

[Stephen Boyd]

If the device is a detachable, we may still probe this device because
there are some button switches, e.g. volume buttons and power buttons,
registered by this driver. Let's allow the device node to be missing row
and column device properties to indicate that the keyboard matrix
shouldn't be registered. This removes an input device on Trogdor devices
such as Wormdingler that don't have a matrix keyboard, but still have
power and volume buttons. That helps userspace understand there isn't
a keyboard present when the detachable keyboard is disconnected.

Cc: Benson Leung <bleung@chromium.org>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Hsin-Yi Wang <hsinyi@chromium.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
---

I tried to use mkbp info to query the number of rows and columns, but my
EC firmware doesn't have commit 8505881ed0b9 ("mkbp: Separate MKBP_INFO
host command from the keyboard driver") so it always returns 8 and 13
for the rows and columns. Sigh. With updated firmware we could query it,
or we could rely on DT like we do already.

Originally I was setting the properties to 0, but
matrix_keypad_parse_properties() spits out an error message in that case
and so it seems better to delete the properties and check for their
existence instead. Another alternative would be to change the compatible
to be "google,cros-ec-keyb-switches" or something that indicates there
are only switches and no matrix keyboard.

 drivers/input/keyboard/cros_ec_keyb.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/input/keyboard/cros_ec_keyb.c b/drivers/input/keyboard/cros_ec_keyb.c
index 6534dfca60b4..ac9a953bff02 100644
--- a/drivers/input/keyboard/cros_ec_keyb.c
+++ b/drivers/input/keyboard/cros_ec_keyb.c
@@ -537,6 +537,15 @@ static int cros_ec_keyb_register_matrix(struct cros_ec_keyb *ckdev)
 	u32 key_pos;
 	unsigned int row, col, scancode, n_physmap;
 
+	/*
+	 * No rows and columns? There isn't a matrix but maybe there are
+	 * switches to register in cros_ec_keyb_register_bs() because this is a
+	 * detachable device.
+	 */
+	if (!device_property_read_bool(dev, "keypad,num-rows") &&
+	    !device_property_read_bool(dev, "keypad,num-cols"))
+		return 0;
+
 	err = matrix_keypad_parse_properties(dev, &ckdev->rows, &ckdev->cols);
 	if (err)
 		return err;
-- 
https://chromeos.dev

Re: [PATCH 1/2] Input: cros-ec-keyb: Only register keyboard if rows/columns exist

[Doug Anderson]

Hi,

On Tue, Apr 12, 2022 at 8:33 PM Stephen Boyd <swboyd@chromium.org> wrote:
>
> If the device is a detachable, we may still probe this device because
> there are some button switches, e.g. volume buttons and power buttons,
> registered by this driver. Let's allow the device node to be missing row
> and column device properties to indicate that the keyboard matrix
> shouldn't be registered. This removes an input device on Trogdor devices
> such as Wormdingler that don't have a matrix keyboard, but still have
> power and volume buttons. That helps userspace understand there isn't
> a keyboard present when the detachable keyboard is disconnected.
>
> Cc: Benson Leung <bleung@chromium.org>
> Cc: Guenter Roeck <groeck@chromium.org>
> Cc: Douglas Anderson <dianders@chromium.org>
> Cc: Hsin-Yi Wang <hsinyi@chromium.org>
> Signed-off-by: Stephen Boyd <swboyd@chromium.org>
> ---
>
> I tried to use mkbp info to query the number of rows and columns, but my
> EC firmware doesn't have commit 8505881ed0b9 ("mkbp: Separate MKBP_INFO
> host command from the keyboard driver") so it always returns 8 and 13
> for the rows and columns. Sigh. With updated firmware we could query it,
> or we could rely on DT like we do already.
>
> Originally I was setting the properties to 0, but
> matrix_keypad_parse_properties() spits out an error message in that case
> and so it seems better to delete the properties and check for their
> existence instead. Another alternative would be to change the compatible
> to be "google,cros-ec-keyb-switches" or something that indicates there
> are only switches and no matrix keyboard.
>
>  drivers/input/keyboard/cros_ec_keyb.c | 9 +++++++++
>  1 file changed, 9 insertions(+)

I do wonder if there will be any unintentional side effects here.
Specifically, even though there is truly no keyboard here, I wonder if
anything in the system is relying on the EC to simulate keypresses
even on tablets where the keyboard isn't actually there...

OK, I guess not. While I think it _used_ to be the case that you could
simulate keyboard inputs from the EC console even for devices w/out a
keyboard, it doesn't seem to be the case anymore. I just tried it and
nothing made it through to the AP.

Seems reasonable to me:

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

Re: [PATCH 1/2] Input: cros-ec-keyb: Only register keyboard if rows/columns exist

[Dmitry Torokhov]

Hi Stephen,

On Tue, Apr 12, 2022 at 08:33:33PM -0700, Stephen Boyd wrote:
> If the device is a detachable, we may still probe this device because
> there are some button switches, e.g. volume buttons and power buttons,
> registered by this driver. Let's allow the device node to be missing row
> and column device properties to indicate that the keyboard matrix
> shouldn't be registered. This removes an input device on Trogdor devices
> such as Wormdingler that don't have a matrix keyboard, but still have
> power and volume buttons. That helps userspace understand there isn't
> a keyboard present when the detachable keyboard is disconnected.
> 
> Cc: Benson Leung <bleung@chromium.org>
> Cc: Guenter Roeck <groeck@chromium.org>
> Cc: Douglas Anderson <dianders@chromium.org>
> Cc: Hsin-Yi Wang <hsinyi@chromium.org>
> Signed-off-by: Stephen Boyd <swboyd@chromium.org>
> ---
> 
> I tried to use mkbp info to query the number of rows and columns, but my
> EC firmware doesn't have commit 8505881ed0b9 ("mkbp: Separate MKBP_INFO
> host command from the keyboard driver") so it always returns 8 and 13
> for the rows and columns. Sigh. With updated firmware we could query it,
> or we could rely on DT like we do already.
> 
> Originally I was setting the properties to 0, but
> matrix_keypad_parse_properties() spits out an error message in that case
> and so it seems better to delete the properties and check for their
> existence instead. Another alternative would be to change the compatible
> to be "google,cros-ec-keyb-switches" or something that indicates there
> are only switches and no matrix keyboard.
> 
>  drivers/input/keyboard/cros_ec_keyb.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/input/keyboard/cros_ec_keyb.c b/drivers/input/keyboard/cros_ec_keyb.c
> index 6534dfca60b4..ac9a953bff02 100644
> --- a/drivers/input/keyboard/cros_ec_keyb.c
> +++ b/drivers/input/keyboard/cros_ec_keyb.c
> @@ -537,6 +537,15 @@ static int cros_ec_keyb_register_matrix(struct cros_ec_keyb *ckdev)
>  	u32 key_pos;
>  	unsigned int row, col, scancode, n_physmap;
>  
> +	/*
> +	 * No rows and columns? There isn't a matrix but maybe there are
> +	 * switches to register in cros_ec_keyb_register_bs() because this is a
> +	 * detachable device.
> +	 */
> +	if (!device_property_read_bool(dev, "keypad,num-rows") &&
> +	    !device_property_read_bool(dev, "keypad,num-cols"))

Why are we abusing device_property_read_bool() for properties that are
not flags instead of using device_property_present()?

> +		return 0;
> +
>  	err = matrix_keypad_parse_properties(dev, &ckdev->rows, &ckdev->cols);
>  	if (err)
>  		return err;
> -- 
> https://chromeos.dev
> 

Thanks.

-- 
Dmitry

Re: [PATCH 1/2] Input: cros-ec-keyb: Only register keyboard if rows/columns exist

[Stephen Boyd]

Quoting Dmitry Torokhov (2022-04-24 20:47:03)
> >
> > +     /*
> > +      * No rows and columns? There isn't a matrix but maybe there are
> > +      * switches to register in cros_ec_keyb_register_bs() because this is a
> > +      * detachable device.
> > +      */
> > +     if (!device_property_read_bool(dev, "keypad,num-rows") &&
> > +         !device_property_read_bool(dev, "keypad,num-cols"))
>
> Why are we abusing device_property_read_bool() for properties that are
> not flags instead of using device_property_present()?
>

Because I wrote this using DT APIs first and wasn't aware that
device_property_present() was a thing. I'll resend it with that API
usage.

[RFC/PATCH 2/2] arm64: dts: qcom: sc7180-trogdor: Remove cros-ec keyboard from detachables

[Stephen Boyd]

Trogdor devices that have a detachable keyboard still have a
non-detachable keyboard input device present because we include the
cros-ec-keyboard.dtsi snippet in the top-level sc7180-trogdor.dtsi file
that every variant board includes. We do this because the
keyboard-controller node also provides some buttons like the power
button and volume buttons. Unfortunately, this means we register a
keyboard input device that doesn't do anything on boards with a
detachable keyboard. Let's delete the rows/columns properties of the
device node to indicate that there isn't a matrix keyboard on these
boards.

Cc: Benson Leung <bleung@chromium.org>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Hsin-Yi Wang <hsinyi@chromium.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
---

This is mostly to show an example. The patch will be picked up by qcom
maintainer if the first patch is accepted.

 arch/arm64/boot/dts/qcom/sc7180-trogdor-coachz.dtsi   | 5 +++++
 arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar.dtsi | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/sc7180-trogdor-coachz.dtsi b/arch/arm64/boot/dts/qcom/sc7180-trogdor-coachz.dtsi
index c81805ef2250..4173623cc241 100644
--- a/arch/arm64/boot/dts/qcom/sc7180-trogdor-coachz.dtsi
+++ b/arch/arm64/boot/dts/qcom/sc7180-trogdor-coachz.dtsi
@@ -119,6 +119,11 @@ &i2c9 {
 	status = "disabled";
 };
 
+&keyboard_controller {
+	/delete-property/keypad,num-rows;
+	/delete-property/keypad,num-columns;
+};
+
 &panel {
 	compatible = "boe,nv110wtm-n61";
 };
diff --git a/arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar.dtsi b/arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar.dtsi
index bff2b556cc75..7205062e88b4 100644
--- a/arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar.dtsi
+++ b/arch/arm64/boot/dts/qcom/sc7180-trogdor-homestar.dtsi
@@ -121,6 +121,11 @@ &camcc {
 	status = "okay";
 };
 
+&keyboard_controller {
+	/delete-property/keypad,num-rows;
+	/delete-property/keypad,num-columns;
+};
+
 &panel {
 	compatible = "samsung,atna33xc20";
 	enable-gpios = <&tlmm 12 GPIO_ACTIVE_HIGH>;
-- 
https://chromeos.dev