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From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: Mon, 15 Jan 2024 10:52:36 +0100
Message-ID: <CAMuHMdWSR3ikL7VZYkNOb1Y8mPU5LaUnc8+WLj-Ec99EOWxs_w@mail.gmail.com>
Subject: Re: [DO NOT MERGE v6 22/37] dt-bindings: display: smi,sm501: SMI
 SM501 binding json-schema
To: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: linux-sh@vger.kernel.org, Damien Le Moal <dlemoal@kernel.org>, 
	Rob Herring <robh+dt@kernel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Conor Dooley <conor+dt@kernel.org>, 
	Michael Turquette <mturquette@baylibre.com>, Stephen Boyd <sboyd@kernel.org>, 
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>, Maxime Ripard <mripard@kernel.org>, 
	Thomas Zimmermann <tzimmermann@suse.de>, David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>, 
	Thomas Gleixner <tglx@linutronix.de>, Lorenzo Pieralisi <lpieralisi@kernel.org>, 
	=?UTF-8?Q?Krzysztof_Wilczy=C5=84ski?= <kw@linux.com>, 
	Bjorn Helgaas <bhelgaas@google.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, 
	Jiri Slaby <jirislaby@kernel.org>, Magnus Damm <magnus.damm@gmail.com>, 
	Daniel Lezcano <daniel.lezcano@linaro.org>, Rich Felker <dalias@libc.org>, 
	John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>, Lee Jones <lee@kernel.org>, 
	Helge Deller <deller@gmx.de>, Heiko Stuebner <heiko@sntech.de>, 
	Jernej Skrabec <jernej.skrabec@gmail.com>, Chris Morgan <macromorgan@hotmail.com>, 
	Yang Xiwen <forbidden405@foxmail.com>, Sebastian Reichel <sre@kernel.org>, 
	Linus Walleij <linus.walleij@linaro.org>, Randy Dunlap <rdunlap@infradead.org>, 
	Arnd Bergmann <arnd@arndb.de>, Vlastimil Babka <vbabka@suse.cz>, Hyeonggon Yoo <42.hyeyoo@gmail.com>, 
	David Rientjes <rientjes@google.com>, Baoquan He <bhe@redhat.com>, 
	Andrew Morton <akpm@linux-foundation.org>, Guenter Roeck <linux@roeck-us.net>, 
	Stephen Rothwell <sfr@canb.auug.org.au>, Azeem Shaikh <azeemshaikh38@gmail.com>, 
	Javier Martinez Canillas <javierm@redhat.com>, Max Filippov <jcmvbkbc@gmail.com>, 
	Palmer Dabbelt <palmer@rivosinc.com>, Bin Meng <bmeng@tinylab.org>, 
	Jonathan Corbet <corbet@lwn.net>, Jacky Huang <ychuang3@nuvoton.com>, 
	Lukas Bulwahn <lukas.bulwahn@gmail.com>, Biju Das <biju.das.jz@bp.renesas.com>, 
	=?UTF-8?Q?Uwe_Kleine=2DK=C3=B6nig?= <u.kleine-koenig@pengutronix.de>, 
	Sam Ravnborg <sam@ravnborg.org>, Sergey Shtylyov <s.shtylyov@omp.ru>, 
	Michael Karcher <kernel@mkarcher.dialup.fu-berlin.de>, 
	Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>, linux-ide@vger.kernel.org, 
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, 
	linux-renesas-soc@vger.kernel.org, linux-clk@vger.kernel.org, 
	dri-devel@lists.freedesktop.org, linux-pci@vger.kernel.org, 
	linux-serial@vger.kernel.org, linux-fbdev@vger.kernel.org
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Hi Sato-san,

On Tue, Jan 9, 2024 at 9:24=E2=80=AFAM Yoshinori Sato
<ysato@users.sourceforge.jp> wrote:
> Signed-off-by: Yoshinori Sato <ysato@users.sourceforge.jp>

Thanks for your patch!

> ---
>  .../bindings/display/smi,sm501.yaml           | 417 ++++++++++++++++++
>  1 file changed, 417 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/display/smi,sm501.y=
aml

Surely Documentation/devicetree/bindings/display/sm501fb.txt should
be removed, too?

> --- /dev/null
> +++ b/Documentation/devicetree/bindings/display/smi,sm501.yaml

> +  crt:
> +    type: object
> +    description: CRT output control
> +    properties:
> +      edid:
> +        $ref: /schemas/types.yaml#/definitions/uint8-array
> +        description: |
> +          verbatim EDID data block describing attached display.
> +          Data from the detailed timing descriptor will be used to
> +          program the display controller.
> +
> +      smi,flags:
> +        $ref: /schemas/types.yaml#/definitions/string-array
> +        description: Display control flags.
> +        items:
> +          anyOf:
> +            - const: use-init-done
> +            - const: disable-at-exit
> +            - const: use-hwcursor
> +            - const: use-hwaccel

The "use-*" flags look like software policy, not hardware description,
and thus do not belong in DT?

> +            - const: panel-no-fpen
> +            - const: panel-no-vbiasen
> +            - const: panel-inv-fpen
> +            - const: panel-inv-vbiasen
> +        maxItems: 8
> +
> +      bpp:
> +        $ref: /schemas/types.yaml#/definitions/uint32
> +        description: Color depth
> +
> +  panel:
> +    type: object
> +    description: Panel output control
> +    properties:
> +      edid:
> +        $ref: /schemas/types.yaml#/definitions/uint8-array
> +        description: |
> +          verbatim EDID data block describing attached display.
> +          Data from the detailed timing descriptor will be used to
> +          program the display controller.
> +
> +      smi,flags:
> +        $ref: /schemas/types.yaml#/definitions/string-array
> +        description: Display control flags.
> +        items:
> +          anyOf:
> +            - const: use-init-done
> +            - const: disable-at-exit
> +            - const: use-hwcursor
> +            - const: use-hwaccel

The "use-*" flags look like software policy, not hardware description,
and thus do not belong in DT?

> +            - const: panel-no-fpen
> +            - const: panel-no-vbiasen
> +            - const: panel-inv-fpen
> +            - const: panel-inv-vbiasen
> +        maxItems: 8
> +
> +      bpp:
> +        $ref: /schemas/types.yaml#/definitions/uint32
> +        description: Color depth
> +
> +  smi,devices:
> +    $ref: /schemas/types.yaml#/definitions/string-array
> +    description: Select SM501 device functions.
> +    items:
> +      anyOf:
> +        - const: usb-host
> +        - const: usb-slave
> +        - const: ssp0
> +        - const: ssp1
> +        - const: uart0
> +        - const: uart1
> +        - const: fbaccel
> +        - const: ac97
> +        - const: i2s
> +        - const: gpio
> +    minItems: 1
> +    maxItems: 10

I think it would be better to have individual subnodes for the sub devices,
with status =3D "ok"/"disabled".

If you go that route, you do need some fallback code to handle the lack
of subnodes in the existing user in arch/powerpc/boot/dts/charon.dts.

BTW, why can sm501_pci_initdata get away with setting ".devices
=3D SM501_USE_ALL"?  Or, would it hurt to enable all subdevices
unconditionally?

> +
> +  smi,mclk:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    description: mclk frequency.
> +
> +  smi,m1xclk:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    description: m1xclk frequency.

These two should be clock specifiers (i.e. phandles pointing to clock
nodes + optional clock indices).

> +
> +  misc-timing:
> +    type: object
> +    description: Miscellaneous Timing register values.
> +    properties:
> +      ex:
> +        $ref: /schemas/types.yaml#/definitions/uint32
> +        description: Extend bus holding time.
> +        enum: [0, 16, 32, 48, 64, 80, 96, 112, 128, 144, 160, 176, 192, =
208, 224, 240]
> +
> +      xc:
> +        $ref: /schemas/types.yaml#/definitions/string
> +        description: Xscale clock input select.
> +        items:
> +          enum:
> +            - internal-pll
> +            - hclk
> +            - gpio33

Software policy instead of hardware description again?

I am not familiar with how the SM501 works, so I cannot comment on
the other properties, but several of them look like they need rework.

Gr{oetje,eeting}s,

                        Geert

--=20
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k=
org

In personal conversations with technical people, I call myself a hacker. Bu=
t
when I'm talking to journalists I just say "programmer" or something like t=
hat.
                                -- Linus Torvalds