On Tue, Apr 14, 2009 at 11:20:03AM +0200, Guennadi Liakhovetski wrote:
> On Tue, 14 Apr 2009, Sascha Hauer wrote:
>
> > On Tue, Apr 14, 2009 at 10:57:32AM +0200, Guennadi Liakhovetski wrote:
> > > On Thu, 9 Apr 2009, Guennadi Liakhovetski wrote:
>
> [snip]
>
> > > > > +static unsigned long pcm990_camera_query_bus_param(struct
> > > > > soc_camera_link *link)
> > > > > +{
> > > > > + int ret;
> > > > > +
> > > > > + if (!gpio_bus_switch) {
> > > > > + ret = gpio_request(NR_BUILTIN_GPIO + 1, "camera");
> > > >
> > > > There's no gpio_free() now... So, for example, you cannot unload the
> > > > extender driver any more, unloading i2c adapter driver (i2c-pxa)
> > > > produces
> > > > ugly stuff like
> > > >
> > > > pca953x 0-0041: gpiochip_remove() failed, -16
> > > >
> > > > So, we either have to request and free the GPIO in each query / set, or
> > > > we
> > > > need an explicit .free_bus() call in soc_camera_link. None of the two
> > > > really pleases me, but maybe the latter is slightly less ugly, what do
> > > > you
> > > > think?
> > > >
> > > > Thanks
> > > > Guennadi
> > > >
> > > > > + if (!ret) {
> > > > > + gpio_bus_switch = NR_BUILTIN_GPIO + 1;
> > > > > + gpio_direction_output(gpio_bus_switch, 0);
> > > > > + } else
> > > > > + gpio_bus_switch = -EINVAL;
> > > > > }
> > >
> > > If you first do not load pca953x and try to start capture, thus calling
> > > pcm990_camera_query_bus_param(), gpio_request() will fail and you get
> > > gpio_bus_switch < 0. Then if you load pca953x it doesn't help any more -
> > > by testing for "if (!gpio_bus_switch)" you do not retry after the first
> > > error.
> >
> > So how do we proceed? Add init/exit functions for the bus?
>
> If you don't object, I'll just add a .free_bus method to soc_camera_link,
> and switch pcm990 to only use two values: a negative value for a
> non-allocated gpio - either before the first attempt or after an error,
> thus re-trying every time if gpio is negative, in case a driver has been
> loaded in the meantime.
For the sake of symmetry, shouldn't we have an init function aswell?
Sascha
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