On Thu, Apr 11, 2024 at 5:07 PM Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx> wrote: > > On 11/04/2024 13:01, Binbin Zhou wrote: > > On Thu, Apr 11, 2024 at 4:26 PM Krzysztof Kozlowski > > <krzysztof.kozlowski@xxxxxxxxxx> wrote: > >> > >> On 11/04/2024 11:16, Binbin Zhou wrote: > >>> Add Loongson PWM controller binding with DT schema format using > >>> json-schema. > >>> > >>> Signed-off-by: Binbin Zhou <zhoubinbin@xxxxxxxxxxx> > >> > >> > >>> +properties: > >>> + compatible: > >>> + oneOf: > >>> + - const: loongson,ls7a-pwm > >>> + - items: > >>> + - enum: > >>> + - loongson,ls2k0500-pwm > >>> + - loongson,ls2k1000-pwm > >>> + - loongson,ls2k2000-pwm > >>> + - const: loongson,ls7a-pwm > >>> + > >>> + reg: > >>> + maxItems: 1 > >>> + > >>> + interrupts: > >>> + maxItems: 1 > >>> + > >>> + clocks: > >>> + maxItems: 1 > >>> + > >>> + '#pwm-cells': > >>> + description: > >>> + The first cell must have a value of 0, which specifies the PWM output signal; > >> > >> If you have always the same value in PWM phandle, why encoding it in the > >> phandle in the first place? What's the benefit of passing 0? > > > > Hi Krzysztof: > > > > My thoughts are: > > First of all, our pwm has only one output signal, so it can only be 0. > > Also, as you know from the pwm xlate function, the first cell is the > > pwm index, so I fixed it to be 0 here. > > > > The xlate function: > > https://elixir.bootlin.com/linux/v6.8/source/drivers/pwm/core.c#L106 > > You refer for xlate for PWM with three cells. You do not have three > cells, as you have only on signal, so why insisting on using other > xlate? Do you do the same for clocks? Or resets? > > I don't think you use appropriate argument in this discussion. We talk > about hardware and your argument "I don't want to use my own xlate in > the driver" is about driver. > Hi Krzysztof: Thanks for your comments. Emm... Indeed, I used to think about it from the driver's perspective. >From the binding perspective, two cells really should be more appropriate. I try to make the following changes in the next version patchset: '#pwm-cells': description: The first cell is the period in nanoseconds; The second cell flag supported by this binding is PWM_POLARITY_INVERTED. const: 2 Accordingly, the custom xlate function will be used in the driver. Thanks. Binbin > > Best regards, > Krzysztof >
