On Thu, Sep 04, 2008 at 05:21:05PM +0800, Eric Miao wrote:
> The GPIO connected to ADS7846 nPENIRQ signal is usually used to get
> the pendown state as well. Introduce a .gpio_pendown, and use this
> to decide the pendown state if .get_pendown_state is NULL.
> +static int get_pendown_state(struct ads7846 *ts)
> +{
> + if (ts->get_pendown_state)
> + return ts->get_pendown_state();
> +
> + if (ts->gpio_pendown != -1)
> + return !gpio_get_value(ts->gpio_pendown);
> +
> + return 0;
> +}
> +
> + int gpio_pendown; /* the GPIO usually connected to PENIRQ
> + * and used to decide pendown state
> + * (-1) to use (*get_pendown_state) */
> +
The comment doesn't match the code. get_pendown_state() is used if it's
non-NULL, otherwise, the GPIO if it's not -1.
I'm getting a little worried about these tests for valid gpio numbers in
drivers - some check for non-zero, this one checks for not -1. I get the
feeling that this is storing up problems for later.
Maybe using gpio_is_valid() would be a good idea?
But... a related question: do we need to do the check here? Surely either
a pendown function is going to be supplied, or if not we're going to use
a GPIO, in which case the GPIO better be valid. Maybe something to check
at driver initialisation time only?
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