[PATCH v12 2/6] video: add of helper for videomode

[Thierry Reding]

On Wed, Nov 21, 2012 at 12:48:43PM +0100, Steffen Trumtrar wrote:
> Hi!
> 
> On Wed, Nov 21, 2012 at 10:12:43AM +0000, Manjunathappa, Prakash wrote:
> > Hi Steffen,
> > 
> > On Tue, Nov 20, 2012 at 21:24:52, Steffen Trumtrar wrote:
> > > +/**
> > > + * of_get_display_timings - parse all display_timing entries from a device_node
> > > + * @np: device_node with the subnodes
> > > + **/
> > > +struct display_timings *of_get_display_timings(const struct device_node *np)
> > > +{
> > > +	struct device_node *timings_np;
> > > +	struct device_node *entry;
> > > +	struct device_node *native_mode;
> > > +	struct display_timings *disp;
> > > +
> > > +	if (!np) {
> > > +		pr_err("%s: no devicenode given\n", __func__);
> > > +		return NULL;
> > > +	}
> > > +
> > > +	timings_np = of_find_node_by_name(np, "display-timings");
> > 
> > I get below build warnings on this line
> > drivers/video/of_display_timing.c: In function 'of_get_display_timings':
> > drivers/video/of_display_timing.c:109:2: warning: passing argument 1 of 'of_find_node_by_name' discards qualifiers from pointer target type
> > include/linux/of.h:167:28: note: expected 'struct device_node *' but argument is of type 'const struct device_node *'
> > 
> > > + * of_display_timings_exists - check if a display-timings node is provided
> > > + * @np: device_node with the timing
> > > + **/
> > > +int of_display_timings_exists(const struct device_node *np)
> > > +{
> > > +	struct device_node *timings_np;
> > > +
> > > +	if (!np)
> > > +		return -EINVAL;
> > > +
> > > +	timings_np = of_parse_phandle(np, "display-timings", 0);
> > 
> > Also here:
> > drivers/video/of_display_timing.c: In function 'of_display_timings_exists':
> > drivers/video/of_display_timing.c:209:2: warning: passing argument 1 of 'of_parse_phandle' discards qualifiers from pointer target type
> > include/linux/of.h:258:28: note: expected 'struct device_node *' but argument is of type 'const struct device_node *'
> > 
> 
> The warnings are because the of-functions do not use const pointers where they
> should. I had two options: don't use const pointers even if they should be and
> have no warnings or use const pointers and have a correct API. (Third option:
> send patches for of-functions). I chose the second option.

Maybe a better approach would be a combination of 1 and 3: don't use
const pointers for struct device_node for now and bring the issue up
with the OF maintainers, possibly with patches attached that fix the
problematic functions.

Thierry
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