On Monday, February 08, 2010 2:04 PM, Andrew Clayton wrote:
> While trying to get a rotary encoder working under a beagle board using
> the drivers/input/misc/rotary-encoder.c driver, we found that even with
> the right pin mux settings configured through /sys/kernel/debug/omap_mux/*,
> i.e INPUT_PULLUP and MODE4, the gpio_get_value() functions only ever
> returned 1.
>
> By explicitly calling gpio_direction_input() after each requested gpio,
> the driver started working and started returning correct input events.
>
> The following is the patch that works for us. What do you think?
On the ep93xx the gpio's default as inputs. The gpio's must default as
outputs on the beagle board. I never noticed the missing direction set
call.
Tested-by: H Hartley Sweeten <hsweeten@xxxxxxxxxxxxxxxxxxx>
> Cheers,
> Andrew
>
>
> Set the gpio direction to input for each requested gpio.
>
> Even with the correct pin mux settings, you still need to explicitly
> set the gpio direction. Call gpio_direction_input() after each
> requested gpio.
>
> Signed-off-by: Andrew Clayton <andrew@xxxxxxxxxxxxxxxxxx>
> ---
> diff --git a/drivers/input/misc/rotary_encoder.c b/drivers/input/misc/rotary_encoder.c
> index 3b9f588..4ae0793 100644
> --- a/drivers/input/misc/rotary_encoder.c
> +++ b/drivers/input/misc/rotary_encoder.c
> @@ -152,6 +152,13 @@ static int __devinit rotary_encoder_probe(struct platform_device *pdev)
> goto exit_unregister_input;
> }
>
> + err = gpio_direction_input(pdata->gpio_a);
> + if (err) {
> + dev_err(&pdev->dev, "unable to set GPIO %d for input\n",
> + pdata->gpio_a);
> + goto exit_unregister_input;
> + }
> +
> err = gpio_request(pdata->gpio_b, DRV_NAME);
> if (err) {
> dev_err(&pdev->dev, "unable to request GPIO %d\n",
> @@ -159,6 +166,13 @@ static int __devinit rotary_encoder_probe(struct platform_device *pdev)
> goto exit_free_gpio_a;
> }
>
> + err = gpio_direction_input(pdata->gpio_b);
> + if (err) {
> + dev_err(&pdev->dev, "unable to set GPIO %d for input\n",
> + pdata->gpio_b);
> + goto exit_free_gpio_a;
> + }
> +
> /* request the IRQs */
> err = request_irq(encoder->irq_a, &rotary_encoder_irq,
> IORESOURCE_IRQ_HIGHEDGE | IORESOURCE_IRQ_LOWEDGE,
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