On Thu, Nov 12, 2015 at 02:55:00PM +0100, Thierry Reding wrote: > On Thu, Nov 12, 2015 at 02:45:20PM +0100, Uwe Kleine-König wrote: > > On Thu, Nov 12, 2015 at 02:28:37PM +0100, Thierry Reding wrote: > > > On Thu, Nov 12, 2015 at 01:54:22PM +0100, LABBE Corentin wrote: > > > > On Thu, Nov 12, 2015 at 01:29:23PM +0100, Thierry Reding wrote: > > > > > On Thu, Nov 12, 2015 at 08:26:03AM +0100, LABBE Corentin wrote: > > > > > > of_match_device could return NULL, and so cause a NULL pointer > > > > > > > > > > No. There is no way that of_match_device() can ever fail. The driver > > > > > core uses the same table to match the OF device to the driver, so the > > > > > only case where of_match_device() would return NULL is if no match was > > > > > found, in which case the tegra_i2c_probe() function would never have > > > > > been called in the first place. > > > > > > > > > > Thierry > > > > > > > > > > > > > In a parallel thread for i2c-rcar, the conclusion was different. > > > > https://lkml.org/lkml/2015/11/12/83 > > > > > > The conclusion was the same: there should be no case where this happens. > > > The example that Uwe gave is hypothetical and not valid DT in the first > > > place. So instead of chickening out I think it'd be better to just crash > > > to make sure people fix the DT. > > > > It depends in your trust in the DT. Just because it's not advisable to > > do something that is not documented usually isn't a good excuse to not > > handle broken input. That't the case for webserver requests, arguments > > to system calls and several more. I admit DT is a bit special because > > you have to assume it's trusted, but still handling errors in a sane way > > is IMHO nice. > > Given that it's supposed to be provided by firmware and possibly from a > ROM, crashing might be a better motivation for fixing it than erroring > out, which people might just ignore or not notice until it's too late. > > > > On a side-note I think that platform_match() should be stricter and do > > > something like this instead: > > > > > > if (dev->of_node) { > > > if (of_driver_match_device(dev, drv)) > > > return 1; > > > > > > return 0; > > > } > > That's equivalent to > > > > if (dev->of_node) > > return of_driver_match_device(dev, drv); > > > > and was already suggested in the thread referenced from my reply to > > http://article.gmane.org/gmane.linux.kernel/2083641 :-) > > Ah, too many cross-reference =) FWIW: > > Acked-by: Thierry Reding <treding@xxxxxxxxxx> > Just for be sure, since the thread goes in lot of direction, you ack my patch ? Perhaps is it better that I resent a version which use of_device_get_match_data() ? Regards -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
