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

[Marco Felsch <m.felsch@pengutronix.de>]

Hi Andy,

On 19-11-27 14:59, Andy Shevchenko wrote:
> 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
> 
> 
> > +	/* Recover from hibernate mode if hardware supports it */
> > +	if (tsdata->wake_gpio) {
> > +		gpiod_set_value_cansleep(tsdata->wake_gpio, 0);
> > +		usleep_range(5000, 6000);
> > +		gpiod_set_value_cansleep(tsdata->wake_gpio, 1);
> > +		msleep(300);
> > +	} else if (tsdata->reset_gpio) {
> > +		gpiod_set_value_cansleep(tsdata->reset_gpio, 1);
> > +		usleep_range(5000, 6000);
> > +		gpiod_set_value_cansleep(tsdata->reset_gpio, 0);
> > +		msleep(300);
> > +	}
> 
> Perhaps
> 
> static void edt_ft5x06_ts_toggle_gpio(struct gpio_desc *gpiod)
> {
> 	...
> }
> 
> ...resume(...)
> {
> 	...
> 	if (wake_gpio)
> 		...toggle_gpio(wake_gpio);
> 	else if (reset_gpio)
> 		...toggle_gpio(reset_gpio);
> 	...
> }
> 
> ?

Thanks fpr your suggestion but we need to differentiate between reset
and wake logic level. The wake-gpio keeps asserted while the reset is
released. So the edt_ft5x06_ts_toggle_gpio() needs at least a 'is_reset'
parameter but then the simplification is gone.

Regards,
  Marco

> -- 
> With Best Regards,
> Andy Shevchenko
> 
> 
> 

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