Re: [PATCH v2 1/2] dt-bindings: pwm: Allow decimal format in addition to hex format

["Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>]

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On Tue, Nov 22, 2022 at 06:43:55AM +0200, Tony Lindgren wrote:
> * Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> [221121 16:05]:
> > On 21/11/2022 15:48, Tony Lindgren wrote:
> > > * Uwe Kleine-König <u.kleine-koenig@pengutronix.de> [221121 14:30]:
> > >> On Mon, Nov 21, 2022 at 01:55:24PM +0200, Tony Lindgren wrote:
> > >>> Let's allow node numbering in decimal format too.
> > >>>
> > >>> Simple human-readable increments/IDs are usually decimal, hex is only for
> > >>> addresses as noted by Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>.
> > >>>
> > >>> Cc: Thierry Reding <thierry.reding@gmail.com>
> > >>> Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> > >>> Suggested-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> > >>> Signed-off-by: Tony Lindgren <tony@atomide.com>
> > >>> ---
> > >>>  Documentation/devicetree/bindings/pwm/pwm.yaml | 2 +-
> > >>>  1 file changed, 1 insertion(+), 1 deletion(-)
> > >>>
> > >>> diff --git a/Documentation/devicetree/bindings/pwm/pwm.yaml b/Documentation/devicetree/bindings/pwm/pwm.yaml
> > >>> --- a/Documentation/devicetree/bindings/pwm/pwm.yaml
> > >>> +++ b/Documentation/devicetree/bindings/pwm/pwm.yaml
> > >>> @@ -13,7 +13,7 @@ select: false
> > >>>  
> > >>>  properties:
> > >>>    $nodename:
> > >>> -    pattern: "^pwm(@.*|-[0-9a-f])*$"
> > >>> +    pattern: "^pwm(@.*|-([0-9a-f]|1[0-5]))*$"
> > >>
> > >> I wonder why you don't make this:
> > >>
> > >> +    pattern: "^pwm(@.*|-[0-9a-f]*)$"
> > 
> > Yes, the '*' should be within ().
> 
> Sorry I guess I don't follow. So for what type of naming is the second '*'
> actually needed here, or is it needed at all?
> 
> We only want to match the following:
> 
> pwm@1234
> 
> pwm-0
> ...
> pwm-f
> 
> And now also:
> 
> pwm-0
> ...
> pwm-15
> 
> Is there yet another format I'm missing?

I think there is a misunderstanding about the type of pattern here. Do
we talk about a shell pattern where "[0-9a-f]*" matches a name starting
with a hex digit followed by any number of any caracter, or is it a
regexp where the * means "any number of the preceding pattern", so
effectively a word consisting of only hex digits.

The .* part makes me think we're talking about a regexp, so the old
pattern ("^pwm(@.*|-[0-9a-f])*$") means that

	pwm-1-2-3-4

is allowed but

	pwm-10

isn't. And I think what we want is:

	"^pwm(@.*|-[0-9a-f]*)$"

(or maybe better "^pwm(@.+|-[0-9a-f]+)$" ?)

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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