On Wed, 5 Feb 2025 07:33:36 -0800
Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> wrote:
> On Tue, Feb 04, 2025 at 02:01:00PM -0500, Hugo Villeneuve wrote:
> > From: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>
> >
> > The current reset pulse width is measured to be 5us on a
> > Renesas RZ/G2L SOM. The manufacturer's minimum reset pulse width is
> > specified as 10us.
> >
> > Extend reset pulse width to make sure it is long enough on all platforms.
> >
> > Also reword confusing comments about reset pin assertion.
> >
> > Fixes: 5b0c03e24a06 ("Input: Add driver for Cypress Generation 5 touchscreen")
> > Cc: <stable@xxxxxxxxxxxxxxx>
> > Signed-off-by: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>
> > ---
> > drivers/input/touchscreen/cyttsp5.c | 5 ++++-
> > 1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/input/touchscreen/cyttsp5.c b/drivers/input/touchscreen/cyttsp5.c
> > index eafe5a9b8964..bb09e84d0e92 100644
> > --- a/drivers/input/touchscreen/cyttsp5.c
> > +++ b/drivers/input/touchscreen/cyttsp5.c
> > @@ -870,13 +870,16 @@ static int cyttsp5_probe(struct device *dev, struct regmap *regmap, int irq,
> > ts->input->phys = ts->phys;
> > input_set_drvdata(ts->input, ts);
> >
> > - /* Reset the gpio to be in a reset state */
> > + /* Assert gpio to be in a reset state */
> > ts->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
> > if (IS_ERR(ts->reset_gpio)) {
> > error = PTR_ERR(ts->reset_gpio);
> > dev_err(dev, "Failed to request reset gpio, error %d\n", error);
> > return error;
> > }
> > +
> > + fsleep(1000); /* Ensure long-enough reset pulse (minimum 10us). */
> > +
>
> If the manufacturer specified that 10us is enough why do we want to wait
> 100 times longer?
Hi,
10us would do fine. I simply put 1ms because it is then much easier to
see the reset pulse on an oscilloscope when correlating it
with other signals.
Hugo.
--
Hugo Villeneuve
