Re: [PATCH 3/3] watchdog: omap_wdt: add device tree support

[Xiao Jiang]

Cousson, Benoit wrote:
> On 5/30/2012 5:18 AM, Xiao Jiang wrote:
> > Jon Hunter wrote:
> > > On 05/25/2012 05:42 AM, jgq516@xxxxxxxxx wrote:
> > > > From: Xiao Jiang <jgq516@xxxxxxxxx>
> > > >
> > > > Add device table for omap_wdt to support dt.
> > > >
> > > > Signed-off-by: Xiao Jiang <jgq516@xxxxxxxxx>
> > > > ---
> > > > drivers/watchdog/omap_wdt.c | 8 ++++++++
> > > > 1 files changed, 8 insertions(+), 0 deletions(-)
> > > >
> > > > diff --git a/drivers/watchdog/omap_wdt.c b/drivers/watchdog/omap_wdt.c
> > > > index 8285d65..d98c615 100644
> > > > --- a/drivers/watchdog/omap_wdt.c
> > > > +++ b/drivers/watchdog/omap_wdt.c
> > > > @@ -430,6 +430,13 @@ static int omap_wdt_resume(struct
> > > > platform_device *pdev)
> > > > #define omap_wdt_resume NULL
> > > > #endif
> > > >
> > > > +static const struct of_device_id omap_wdt_of_match[] = {
> > > > + { .compatible = "ti,omap3-wdt", },
> > > > + { .compatible = "ti,omap4-wdt", },
>
> If there is no difference between the OMAP3 and the OMAP4 WDT IP, just 
> add one entry "ti,omap3-wdt". And then in the OMAP4 DTS you will just 
> put : compatible = "ti,omap3-wdt"; or compatible =  "ti,omap4-wdt", 
> "ti,omap3-wdt";
> I'm still a little bit confused about the real need for the 
> "ti,omap4-wdt: entry, but it seems to be the way to do it in PPC.
I believe OMAP2, OMAP3 and OMAP4 share the same IP, so how about use 
"ti, omap2-wdt"? and other dts files
put compatible like "ti,omap4-wdt", "ti,omap2-wdt" and "ti,omap4-wdt", 
"ti,omap2-wdt".
> > > > + {},
> > > > +};
> > > > +MODULE_DEVICE_TABLE(of, omap_wdt_of_match);
> > > > +
> > > > static struct platform_driver omap_wdt_driver = {
> > > > .probe = omap_wdt_probe,
> > > > .remove = __devexit_p(omap_wdt_remove),
> > > > @@ -439,6 +446,7 @@ static struct platform_driver omap_wdt_driver = {
> > > > .driver = {
> > > > .owner = THIS_MODULE,
> > > > .name = "omap_wdt",
> > > > + .of_match_table = omap_wdt_of_match,
> > > > },
> > > > };
> > >
> > > I think we need to add some code to the probe function that calls
> > > of_match_device() and ensures we find a match. For example ...
> > >
> > > if (of_have_populated_dt())
> > > if (!of_match_device(omap_wdt_of_match, &pdev->dev))
> > > return -EINVAL;
> > Will add it in v2, thanks for suggestion.
>
> No, in fact this is not needed. We need that mainly when several 
> instances can match the same driver and thus we select the proper one 
> using the of_match_device. Otherwise, just check is the device_node is 
> there.
>
> In that case, the driver does not even care about any DT node so there 
> is no need to add extra code for that. Keep it simple.
Thanks for elaborating, simple is good for this one.

Regards,
Xiao
> Regards,
> Benoit

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