Re: [PATCH 1/2 v6] of: add helper to parse display timings

On Sun, Oct 07, 2012 at 03:38:25PM +0200, Laurent Pinchart wrote:

Hi Steffen,

On Friday 05 October 2012 18:38:58 Steffen Trumtrar wrote:

quoted

On Fri, Oct 05, 2012 at 10:21:37AM -0600, Stephen Warren wrote:

quoted

On 10/05/2012 10:16 AM, Steffen Trumtrar wrote:

quoted

On Thu, Oct 04, 2012 at 12:47:16PM -0600, Stephen Warren wrote:

quoted

On 10/04/2012 11:59 AM, Steffen Trumtrar wrote:

...

quoted

quoted

quoted

+	for_each_child_of_node(timings_np, entry) {
+		struct signal_timing *st;
+
+		st = of_get_display_timing(entry);
+
+		if (!st)
+			continue;

I wonder if that shouldn't be an error?

In the sense of a pr_err not a -EINVAL I presume?! It is a little bit
quiet in case of a faulty spec, that is right.

I did mean return an error; if we try to parse something and can't,
shouldn't we return an error?

I suppose it may be possible to limp on and use whatever subset of modes
could be parsed and drop the others, which is what this code does, but
the code after the loop would definitely return an error if zero timings
were parseable.

If a display supports multiple modes, I think it is better to have a working
mode (even if it is not the preferred one) than have none at all.
If there is no mode at all, that should be an error, right.

If we fail completely in case of an error, DT writers will notice their bugs. 
If we ignore errors silently they won't, and we'll end up with buggy DTs (or, 
to be accurate, even more buggy DTs :-)). I'd rather fail completely in the 
first implementation and add workarounds later only if we need to.

Okay, that is two against one. And if you say it like this, Stephen and you are
right I guess. Fail completely it is then.

Regards,

Steffen

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