[PATCH 1/2] Add functions for HID drivers to react on first open and last close call

[PATCH 1/2] Add functions for HID drivers to react on first open and last close call

[Werner Sembach]

Adds a new function to the hid_driver struct that is called when the
userspace starts using the device, and another one that is called when
userspace stop using the device. With this a hid driver can implement
special suspend handling for devices currently not in use.

Signed-off-by: Werner Sembach <wse@tuxedocomputers.com>
---
 drivers/hid/hid-core.c | 9 ++++++++-
 include/linux/hid.h    | 4 ++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 4497b50799dbf..283917a79ac86 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -2392,6 +2392,9 @@ int hid_hw_open(struct hid_device *hdev)
 		ret = hdev->ll_driver->open(hdev);
 		if (ret)
 			hdev->ll_open_count--;
+
+		if (hdev->driver->on_hid_hw_open)
+			hdev->driver->on_hid_hw_open(hdev);
 	}
 
 	mutex_unlock(&hdev->ll_open_lock);
@@ -2411,8 +2414,12 @@ EXPORT_SYMBOL_GPL(hid_hw_open);
 void hid_hw_close(struct hid_device *hdev)
 {
 	mutex_lock(&hdev->ll_open_lock);
-	if (!--hdev->ll_open_count)
+	if (!--hdev->ll_open_count) {
 		hdev->ll_driver->close(hdev);
+
+		if (hdev->driver->on_hid_hw_close)
+			hdev->driver->on_hid_hw_close(hdev);
+	}
 	mutex_unlock(&hdev->ll_open_lock);
 }
 EXPORT_SYMBOL_GPL(hid_hw_close);
diff --git a/include/linux/hid.h b/include/linux/hid.h
index cdc0dc13c87fe..3b7db4eb3f2f6 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -790,6 +790,8 @@ struct hid_usage_id {
  * @suspend: invoked on suspend (NULL means nop)
  * @resume: invoked on resume if device was not reset (NULL means nop)
  * @reset_resume: invoked on resume if device was reset (NULL means nop)
+ * @on_hid_hw_open: invoked when hid core opens first instance (NULL means nop)
+ * @on_hid_hw_close: invoked when hid core closes last instance (NULL means nop)
  *
  * probe should return -errno on error, or 0 on success. During probe,
  * input will not be passed to raw_event unless hid_device_io_start is
@@ -845,6 +847,8 @@ struct hid_driver {
 	int (*suspend)(struct hid_device *hdev, pm_message_t message);
 	int (*resume)(struct hid_device *hdev);
 	int (*reset_resume)(struct hid_device *hdev);
+	void (*on_hid_hw_open)(struct hid_device *hdev);
+	void (*on_hid_hw_close)(struct hid_device *hdev);
 
 /* private: */
 	struct device_driver driver;
-- 
2.43.0

[PATCH 2/2] Disable touchpad on firmware level while not in use

[Werner Sembach]

Using the new on_hid_hw_open and on_hid_hw_close functions to disable the
touchpad on firmware level while not being in use.

This safes some battery and triggers touchpad-disabled-leds hardwired to
the touchpads firmware, that exist for example on some TongFang barebones.

For a lengthy discussion with all the details see
https://gitlab.freedesktop.org/libinput/libinput/-/issues/558

Signed-off-by: Werner Sembach <wse@tuxedocomputers.com>
---
 drivers/hid/hid-multitouch.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index 82900857bfd87..7289c04f47f17 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -1884,6 +1884,16 @@ static void mt_remove(struct hid_device *hdev)
 	hid_hw_stop(hdev);
 }
 
+static void mt_on_hid_hw_open(struct hid_device *hdev)
+{
+	mt_set_modes(hdev, HID_LATENCY_NORMAL, TOUCHPAD_REPORT_ALL);
+}
+
+static void mt_on_hid_hw_close(struct hid_device *hdev)
+{
+	mt_set_modes(hdev, HID_LATENCY_HIGH, TOUCHPAD_REPORT_NONE);
+}
+
 /*
  * This list contains only:
  * - VID/PID of products not working with the default multitouch handling
@@ -2351,5 +2361,7 @@ static struct hid_driver mt_driver = {
 	.suspend = pm_ptr(mt_suspend),
 	.reset_resume = pm_ptr(mt_reset_resume),
 	.resume = pm_ptr(mt_resume),
+	.on_hid_hw_open = mt_on_hid_hw_open,
+	.on_hid_hw_close = mt_on_hid_hw_close,
 };
 module_hid_driver(mt_driver);
-- 
2.43.0

Re: [PATCH 2/2] Disable touchpad on firmware level while not in use

[Werner Sembach]

Hi,

Am 11.02.25 um 14:39 schrieb Werner Sembach:
> Using the new on_hid_hw_open and on_hid_hw_close functions to disable the
> touchpad on firmware level while not being in use.
>
> This safes some battery and triggers touchpad-disabled-leds hardwired to
> the touchpads firmware, that exist for example on some TongFang barebones.
>
> For a lengthy discussion with all the details see
> https://gitlab.freedesktop.org/libinput/libinput/-/issues/558

Any comments if this is a good idea or not?

Best regards,

Werner

> Signed-off-by: Werner Sembach <wse@tuxedocomputers.com>
> ---
>   drivers/hid/hid-multitouch.c | 12 ++++++++++++
>   1 file changed, 12 insertions(+)
>
> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
> index 82900857bfd87..7289c04f47f17 100644
> --- a/drivers/hid/hid-multitouch.c
> +++ b/drivers/hid/hid-multitouch.c
> @@ -1884,6 +1884,16 @@ static void mt_remove(struct hid_device *hdev)
>   	hid_hw_stop(hdev);
>   }
>   
> +static void mt_on_hid_hw_open(struct hid_device *hdev)
> +{
> +	mt_set_modes(hdev, HID_LATENCY_NORMAL, TOUCHPAD_REPORT_ALL);
> +}
> +
> +static void mt_on_hid_hw_close(struct hid_device *hdev)
> +{
> +	mt_set_modes(hdev, HID_LATENCY_HIGH, TOUCHPAD_REPORT_NONE);
> +}
> +
>   /*
>    * This list contains only:
>    * - VID/PID of products not working with the default multitouch handling
> @@ -2351,5 +2361,7 @@ static struct hid_driver mt_driver = {
>   	.suspend = pm_ptr(mt_suspend),
>   	.reset_resume = pm_ptr(mt_reset_resume),
>   	.resume = pm_ptr(mt_resume),
> +	.on_hid_hw_open = mt_on_hid_hw_open,
> +	.on_hid_hw_close = mt_on_hid_hw_close,
>   };
>   module_hid_driver(mt_driver);

Re: [PATCH 2/2] Disable touchpad on firmware level while not in use

[Jiri Kosina]

On Tue, 4 Mar 2025, Werner Sembach wrote:

> > Using the new on_hid_hw_open and on_hid_hw_close functions to disable the
> > touchpad on firmware level while not being in use.
> >
> > This safes some battery and triggers touchpad-disabled-leds hardwired to
> > the touchpads firmware, that exist for example on some TongFang barebones.
> >
> > For a lengthy discussion with all the details see
> > https://gitlab.freedesktop.org/libinput/libinput/-/issues/558
> 
> Any comments if this is a good idea or not?

Sorry for the delay.

To me this looks like generally a good idea; Benjamin, any comments on the 
hid-mt part?

BTW you'd need to adjust the Subject line of the patches to conform to the 
subsystem style (i.e. HID: core: ....)

Thanks,

-- 
Jiri Kosina
SUSE Labs

Re: [PATCH 2/2] Disable touchpad on firmware level while not in use

[Werner Sembach]

Am 24.04.25 um 11:20 schrieb Jiri Kosina:
> On Tue, 4 Mar 2025, Werner Sembach wrote:
>
>>> Using the new on_hid_hw_open and on_hid_hw_close functions to disable the
>>> touchpad on firmware level while not being in use.
>>>
>>> This safes some battery and triggers touchpad-disabled-leds hardwired to
>>> the touchpads firmware, that exist for example on some TongFang barebones.
>>>
>>> For a lengthy discussion with all the details see
>>> https://gitlab.freedesktop.org/libinput/libinput/-/issues/558
>> Any comments if this is a good idea or not?
> Sorry for the delay.
np
>
> To me this looks like generally a good idea; Benjamin, any comments on the
> hid-mt part?
>
> BTW you'd need to adjust the Subject line of the patches to conform to the
> subsystem style (i.e. HID: core: ....)

sorry an oversight when rewriting the commit log from local testing branch to 
upstream ready

will do in v2 after Benjamins reply

Thanks for looking at this,

Werner

>
> Thanks,
>

Re: [PATCH 2/2] Disable touchpad on firmware level while not in use

[Benjamin Tissoires]

On Apr 24 2025, Jiri Kosina wrote:
> On Tue, 4 Mar 2025, Werner Sembach wrote:
> 
> > > Using the new on_hid_hw_open and on_hid_hw_close functions to disable the
> > > touchpad on firmware level while not being in use.
> > >
> > > This safes some battery and triggers touchpad-disabled-leds hardwired to
> > > the touchpads firmware, that exist for example on some TongFang barebones.
> > >
> > > For a lengthy discussion with all the details see
> > > https://gitlab.freedesktop.org/libinput/libinput/-/issues/558
> > 
> > Any comments if this is a good idea or not?
> 
> Sorry for the delay.
> 
> To me this looks like generally a good idea; Benjamin, any comments on the 
> hid-mt part?

Looks good to me, though my CI is now taking way more time because it's
not expecting to receive data from the device once the initial setup is
done.

> 
> BTW you'd need to adjust the Subject line of the patches to conform to the 
> subsystem style (i.e. HID: core: ....)

Amended locally and pushed (see the notification email).

Cheers,
Benjamin

> 
> Thanks,
> 
> -- 
> Jiri Kosina
> SUSE Labs
> 

Re: [PATCH 1/2] Add functions for HID drivers to react on first open and last close call

[Benjamin Tissoires]

On Tue, 11 Feb 2025 14:39:05 +0100, Werner Sembach wrote:
> Adds a new function to the hid_driver struct that is called when the
> userspace starts using the device, and another one that is called when
> userspace stop using the device. With this a hid driver can implement
> special suspend handling for devices currently not in use.
> 
> 

Applied to hid/hid.git (for-6.16/core), thanks!

[1/2] Add functions for HID drivers to react on first open and last close call
      https://git.kernel.org/hid/hid/c/a98e892c6942
[2/2] Disable touchpad on firmware level while not in use
      https://git.kernel.org/hid/hid/c/6a9e76f75c1a

Cheers,
-- 
Benjamin Tissoires <bentiss@kernel.org>