Re: [PATCH] Input: cyttsp5 - ensure minimum reset pulse width

[Alistair <alistair@alistair23.me>]

On Wed, 5 Feb 2025, at 5:01 AM, Hugo Villeneuve wrote:
> From: Hugo Villeneuve <hvilleneuve@dimonoff.com>
> 
> 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@vger.kernel.org>
> Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>

Acked-by: Alistair Francis <alistair@alistair23.me>

> ---
> 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). */
> +
> gpiod_set_value_cansleep(ts->reset_gpio, 0);
>  
> /* Need a delay to have device up */
> 
> base-commit: 0de63bb7d91975e73338300a57c54b93d3cc151c
> -- 
> 2.39.5
> 
>