Re: [PATCH] dt-bindings: serial: 8250: allow "main" and "uart" as clock names

[Conor Dooley <conor@kernel.org>]

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On Tue, Jul 29, 2025 at 06:53:19AM +0800, Yixun Lan wrote:
> Hi Alex,
> 
> On 17:00 Mon 28 Jul     , Alex Elder wrote:
> > There are two compatible strings defined in "8250.yaml" that require
> > two clocks to be specified, along with their names:
> >   - "spacemit,k1-uart", used in "spacemit/k1.dtsi"
> >   - "nxp,lpc1850-uart", used in "lpc/lpc18xx.dtsi"
> > 
> > When only one clock is used, the name is not required.  However there
> > are two places that do specify a name:
> >   - In "mediatek/mt7623.dtsi", the clock for the "mediatek,mtk-btif"
> >     compatible serial device is named "main"
> >   - In "qca/ar9132.dtsi", the clock for the "ns8250" compatible
> >     serial device is named "uart"
> > 
> > In commit d2db0d7815444 ("dt-bindings: serial: 8250: allow clock 'uartclk'
> > and 'reg' for nxp,lpc1850-uart"), Frank Li added the restriction that two
> > named clocks be used for the NXP platform mentioned above.  Extend that
> > so that the two named clocks used by the SpacemiT platform are similarly
> > restricted.
> > 
> > Add "main" and "uart" as allowed names when a single clock is specified.
> > 
> > Fixes: 2c0594f9f0629 ("dt-bindings: serial: 8250: support an optional second clock")
> > Reported-by: kernel test robot <lkp@intel.com>
> > Closes: https://lore.kernel.org/oe-kbuild-all/202507160314.wrC51lXX-lkp@intel.com/
> > Signed-off-by: Alex Elder <elder@riscstar.com>
> > ---
> >  .../devicetree/bindings/serial/8250.yaml      | 19 ++++++++++++++-----
> >  1 file changed, 14 insertions(+), 5 deletions(-)
> > 
> > diff --git a/Documentation/devicetree/bindings/serial/8250.yaml b/Documentation/devicetree/bindings/serial/8250.yaml
> > index e46bee8d25bf0..cef52ebd8f7da 100644
> > --- a/Documentation/devicetree/bindings/serial/8250.yaml
> > +++ b/Documentation/devicetree/bindings/serial/8250.yaml
> > @@ -61,11 +61,17 @@ allOf:
> >              - const: uartclk
> >              - const: reg
> ..
> >      else:
> would it be better to drop this 'else', and moving following 'if' block
> to the same level with "nxp,lpc1850-uart"?
> 
> the reason here would avoid too many indentions if add more constraint in
> the future if other SoC uart need different clock-names..

I agree, it's more typical to do it that way I think to boot.

Also, why is there a k1/lpc conditional bit that is not part of the
allOf in addition to the bits in the allOf? Can that get merged with the
allOf please?

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