On Wed, Aug 14, 2019 at 03:25:53PM +0800, Baolin Wang wrote: > Hi Uwe, > > On Wed, 14 Aug 2019 at 15:01, Uwe Kleine-König > <u.kleine-koenig@xxxxxxxxxxxxxx> wrote: > > > > Hello Baolin, > > > > On Wed, Aug 14, 2019 at 09:51:34AM +0800, Baolin Wang wrote: > > > On Tue, 13 Aug 2019 at 22:13, Uwe Kleine-König > > > <u.kleine-koenig@xxxxxxxxxxxxxx> wrote: > > > > On Tue, Aug 13, 2019 at 09:46:40PM +0800, Baolin Wang wrote: > > > > > +- assigned-clock-parents: The phandle of the parent clock of PWM clock. > > > > > > > > I'm not sure you need to point out assigned-clocks and > > > > assigned-clock-parents as this is general clk stuff. Also I wonder if > > > > these should be "required properties". > > > > > > I think I should describe any properties used by PWM node, like > > > 'clocks' and 'clock-names' properties, though they are common clock > > > properties. > > > > Then you might want to describe also "status", "assigned-clock-rates", > > "pinctrl-$n", "pinctrl-names", "power-domains", "power-domain-names" and > > probably another dozen I'm not aware of. > > We usually do not describe 'status', but if your device node used > "pinctrl-$n", "pinctrl-names" ... common properties, yes, you should > describe them to let users know what is the purpose of these > properties. That's also asked by DT maintainer Rob. Does this convince you that you should also describe "pinctrl-$n" and the others? If not, why not? We also usually don't describe assigned-clock-parents. For me these are all in the same catagory: Common properties supported for each devicetree node that represents a device. The only difference is that on your board you make use of some but not some others. > > > Yes, they are required. Thanks for your comments. > > > > required in which sense? Why can a Spreadtrum PWM not work when the > > clock parents are unspecified? > > On some Spreadtrum platforms, the default source clock of PWM may not > be enabled, so we should force users to select one available source > clock for PWM output clock. Sounds like a bug in the clk tree of your SoC that shouldn't affect how the PWM is described in the device tree. After all a parent of a clock is supposed to become enabled when the clock gets enabled. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |
