Re: [PATCH v2 5/5] Input: edt-ft5x06 - improve power management operations

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

On Wed, Nov 27, 2019 at 01:09:48PM +0100, Marco Felsch wrote:
> It is possible to bring the device into a deep sleep state. To exit this
> state the reset or wakeup pin must be toggeled as documented in [1].
> Because of the poor documentation I used the several downstream kernels
> [2] and other applications notes [3] to indentify the related registers.
> 
> Furthermore I added the support to disable the device completely. This is
> the most effective power-saving mechanism. Disabling the device don't
> change the suspend logic because the hibernate mode needs a hardware
> reset anyway.
> 
> [1] https://www.newhavendisplay.com/appnotes/datasheets/touchpanel/FT5x26.pdf
> [2] https://github.com/linux-sunxi/linux-sunxi/blob/sunxi-3.4/drivers/input/touchscreen/ft5x_ts.c
>     https://github.com/Pablito2020/focaltech-touch-driver/blob/master/ft5336_driver.c
> [3] https://www.newhavendisplay.com/appnotes/datasheets/touchpanel/FT5x16_registers.pdf
> 
> Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
> ---
> v2:
> - adapt commit message
> - don't return errors during suspend/resume
> - replace dev_err() by dev_warn()
> - add support to disable the regulator too
> 
>  drivers/input/touchscreen/edt-ft5x06.c | 49 ++++++++++++++++++++++++--
>  1 file changed, 47 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/edt-ft5x06.c b/drivers/input/touchscreen/edt-ft5x06.c
> index 8d2ec7947f0e..0bdd3440f684 100644
> --- a/drivers/input/touchscreen/edt-ft5x06.c
> +++ b/drivers/input/touchscreen/edt-ft5x06.c
> @@ -39,6 +39,9 @@
>  #define WORK_REGISTER_NUM_X		0x33
>  #define WORK_REGISTER_NUM_Y		0x34
>  
> +#define PMOD_REGISTER_ACTIVE		0x00
> +#define PMOD_REGISTER_HIBERNATE		0x03
> +
>  #define M09_REGISTER_THRESHOLD		0x80
>  #define M09_REGISTER_GAIN		0x92
>  #define M09_REGISTER_OFFSET		0x93
> @@ -54,6 +57,7 @@
>  
>  #define WORK_REGISTER_OPMODE		0x3c
>  #define FACTORY_REGISTER_OPMODE		0x01
> +#define PMOD_REGISTER_OPMODE		0xa5
>  
>  #define TOUCH_EVENT_DOWN		0x00
>  #define TOUCH_EVENT_UP			0x01
> @@ -1235,9 +1239,29 @@ static int edt_ft5x06_ts_remove(struct i2c_client *client)
>  static int __maybe_unused edt_ft5x06_ts_suspend(struct device *dev)
>  {
>  	struct i2c_client *client = to_i2c_client(dev);
> +	struct edt_ft5x06_ts_data *tsdata = i2c_get_clientdata(client);
> +	int ret;
>  
> -	if (device_may_wakeup(dev))
> +	if (device_may_wakeup(dev)) {
>  		enable_irq_wake(client->irq);

Can we start with preliminary patch dropping calls to enable_irq_wake()
and disable_irq_wake() as device/PM core will tale care of configuring
wake irqs properly for us, since we are now allowing I2C core to mark
the interrupt as wake IRQ.

So we need to do:

	if (device_may_wakeup(dev))
		return 0;

	<execute power down sequence>

Thanks.

-- 
Dmitry