[PATCH v5 09/16] pwm: tegra: Add device tree support

[grant.likely@secretlab.ca (Grant Likely)]

On Tue, 3 Apr 2012 19:55:11 +0200, Thierry Reding <thierry.reding@avionic-design.de> wrote:
> * Stephen Warren wrote:
> > On 04/02/2012 02:37 AM, Thierry Reding wrote:
> > > * Stephen Warren wrote:
> > >> On 03/28/2012 08:33 AM, Thierry Reding wrote:
> > >>> Add auxdata to instantiate the PWFM controller from a device tree,
> > >>> include the corresponding nodes in the dtsi files for Tegra 20 and
> > >>> Tegra 30 and add binding documentation.
> > >>>
> > >>> Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
> > >>> Acked-by: Stephen Warren <swarren@wwwdotorg.org>
> > >>
> > >>> diff --git a/drivers/pwm/pwm-tegra.c b/drivers/pwm/pwm-tegra.c
> > >> ...
> > >>> +#ifdef CONFIG_OF
> > >>> +static struct of_device_id tegra_pwm_of_match[] = {
> > >>> +	{ .compatible = "nvidia,tegra20-pwm" },
> > >>> +	{ .compatible = "nvidia,tegra30-pwm" },
> > >>
> > >> Could you swap those two lines, so that tegra30-pwm matches first. It
> > >> makes no difference at present, but might in the future if the driver
> > >> actually has to differentiate the two SoCs.
> > > 
> > > I thought the matching order was determined by the compatible property in the
> > > device tree, not the OF match table of the driver.
> > 
> > At least logically, yes. However, of_match_device() appears to iterate
> > over each match table entry, checking whether it matches any string in
> > the compatible flag. Perhaps this could be considered a bug?
> 
> It certainly is counter-intuitive. Maybe Grant or Rob can comment?

Yes, it is a bug.  The order of of_device_id should be entirely
irrelevant, and the order in the DT compatible property should
determine which match entry is returned.

g.