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

[Alex Elder]

On 7/29/25 4:08 PM, Conor Dooley wrote:
> On Tue, Jul 29, 2025 at 04:04:05PM -0500, Alex Elder wrote:
> > On 7/29/25 12:54 PM, Conor Dooley wrote:
> > > 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@xxxxxxxxx>
> > > > > Closes: https://lore.kernel.org/oe-kbuild-all/202507160314.wrC51lXX-lkp@xxxxxxxxx/
> > > > > Signed-off-by: Alex Elder <elder@xxxxxxxxxxxx>
> > > > > ---
> > > > >    .../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?
> >
> > Are you talking about the blank line here?
>
> No, I'm talking about what's down around line 270 in the binding.

Oh wow that's in a weird spot, and it might be redundant?

Anyway I'll work on getting that fixed too before I send
my next version.

					-Alex

> >      then:
> >        oneOf:
> >          - required: [ clock-frequency ]
> >          - required: [ clocks ]
> >                             <------ this blank line
> >    - if:
> >        properties:
> >          compatible:
> >            contains:
> >              const: nxp,lpc1850-uart
> >      then:
> >
> > I didn't notice that before.  It got inserted with commit
> > d2db0d7815444 ("dt-bindings: serial: 8250: allow clock
> > 'uartclk' and 'reg' for nxp,lpc1850-uart").
> >
> > If so, yes I'll remove that as well when I update the patch to
> > get rid of the else as Yixun suggests.
> >
> > Greg won't take this for a couple weeks so I'll hold off sending
> > v2 for a while.
> >
> > 					-Alex