Re: [PATCH] Input: s6sy761 - fix resume ordering and restore sensing

[Dmitry Torokhov]

Hi David,

On Wed, Sep 23, 2026 at 03:27:06PM +0200, David Heidelberg via B4 Relay wrote:
> From: David Heidelberg <david@xxxxxxx>
> 
> System suspend powers the controller off and resume powers it back on,
> but the resume path enables the interrupt before s6sy761_power_on()
> checks the boot. The firmware raises its boot-complete event on the
> interrupt line, the threaded handler consumes it, s6sy761_power_on()
> then reads an empty event and resume fails with -ENODEV, skipping the
> touch function setup:
> 
>   s6sy761 2-0048: PM: dpm_run_callback(): s6sy761_resume [s6sy761] returns -19
> 
> Power the chip on first and only then unmask the interrupt. Once resume
> completes the boot handshake the chip comes back with sensing off, as
> at probe where input_open() turns it on, so the touchscreen stays dead
> after resume. Send SENSE_ON again when the input device is open.
> 
> Tested on a Pixel 3 XL over several s2idle cycles: resume succeeds and
> the touch function and sense status match the pre-suspend state.
> 
> Assisted-by: LLM
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 0145a7141e59 ("Input: add support for the Samsung S6SY761 touchscreen")
> Signed-off-by: David Heidelberg <david@xxxxxxx>
> ---
>  drivers/input/touchscreen/s6sy761.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/input/touchscreen/s6sy761.c b/drivers/input/touchscreen/s6sy761.c
> index 0f24a9b730635..c52c45a7d1029 100644
> --- a/drivers/input/touchscreen/s6sy761.c
> +++ b/drivers/input/touchscreen/s6sy761.c
> @@ -495,20 +495,29 @@ static int s6sy761_suspend(struct device *dev)
>  	s6sy761_power_off(sdata);
>  
>  	return 0;
>  }
>  
>  static int s6sy761_resume(struct device *dev)
>  {
>  	struct s6sy761_data *sdata = dev_get_drvdata(dev);
> +	int err;
>  
> +	err = s6sy761_power_on(sdata);
>  	enable_irq(sdata->client->irq);

Why are we enabling the interrupt even if power on failed?

> +	if (err)
> +		return err;
>  
> -	return s6sy761_power_on(sdata);
> +	guard(mutex)(&sdata->input->mutex);
> +
> +	if (!input_device_enabled(sdata->input))
> +		return 0;
> +
> +	return i2c_smbus_write_byte(sdata->client, S6SY761_SENSE_ON);

Explicit return err/return 0 please - there are multiple failure points
in this function.

Thanks.

-- 
Dmitry