linux-kernel - Re: [PATCH v4 1/2] dt-bindings: media: i2c: Add ov2735 sensor

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Message-ID:
 <PN3P287MB3519907E3C113D6CD9D564E3FF51A@PN3P287MB3519.INDP287.PROD.OUTLOOK.COM>
Date: Thu, 17 Jul 2025 11:55:49 +0000
From: Hardevsinh Palaniya <hardevsinh.palaniya@...iconsignals.io>
To: Krzysztof Kozlowski <krzk@...nel.org>
CC: "sakari.ailus@...ux.intel.com" <sakari.ailus@...ux.intel.com>,
	"andriy.shevchenko@...ux.intel.com" <andriy.shevchenko@...ux.intel.com>,
	"laurent.pinchart@...asonboard.com" <laurent.pinchart@...asonboard.com>,
	"krzk+dt@...nel.org" <krzk+dt@...nel.org>, Himanshu Bhavani
	<himanshu.bhavani@...iconsignals.io>, Mauro Carvalho Chehab
	<mchehab@...nel.org>, Rob Herring <robh@...nel.org>, Conor Dooley
	<conor+dt@...nel.org>, Hans Verkuil <hverkuil@...all.nl>, Bryan O'Donoghue
	<bryan.odonoghue@...aro.org>, André Apitzsch
	<git@...tzsch.eu>, Ricardo Ribalda <ribalda@...omium.org>, Heimir Thor
 Sverrisson <heimir.sverrisson@...il.com>, Matthias Fend
	<matthias.fend@...end.at>, Sylvain Petinot <sylvain.petinot@...s.st.com>,
	Jingjing Xiong <jingjing.xiong@...el.com>, Benjamin Mugnier
	<benjamin.mugnier@...s.st.com>, Dongcheng Yan <dongcheng.yan@...el.com>, Arnd
 Bergmann <arnd@...db.de>, Hans de Goede <hansg@...nel.org>,
	"linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 1/2] dt-bindings: media: i2c: Add ov2735 sensor

> On 17/07/2025 09:28, Hardevsinh Palaniya wrote:
> >  Hi Krzysztof,
> > 
> > > On Wed, Jul 16, 2025 at 07:14:16PM +0530, Hardevsinh Palaniya wrote:
> > > > +        properties:
> > > > +          data-lanes:
> > > > +            items:
> > > > +              - const: 1
> > > > +              - const: 2
> > > > +          link-frequencies: true
> > >
> > > Drop
> > >
> > > I don't understand why this appeared. I don't think anyone asked for it?
> >
> > Laurent suggested validating the link frequency in the Device Tree.
> >
> > Link[1]: https://lore.kernel.org/linux-media/20250710212131.GG22436@pendragon.ideasonboard.com/
> 
> ... and I do not see here validation "that the link frequencies
> specified in DT match".
> 
> How do you validate that 1111 Hz is not / is a valid link frequency? How
> did you exactly resolve the comment about validating?

In the ov2735_parse_endpoint() function, the driver validates the link frequency
from DT using `v4l2_link_freq_to_bitmap()`. If an unsupported value like 1111 Hz is
provided, it returns an error: 

ret = v4l2_link_freq_to_bitmap(ov2735->dev, bus_cfg.link_frequencies,
                               bus_cfg.nr_of_link_frequencies,
                               link_freq_menu_items,
                               ARRAY_SIZE(link_freq_menu_items),
                               &link_freq_bitmap);
if (ret) {
        ret = dev_err_probe(ov2735->dev,
                            -EINVAL, "only 420MHz frequency is available\n");
        goto error_out;
}

So, validation is already done in the driver.

I understand that `link-frequencies: true` in the schema only declares the property
without restricting values. Would you prefer the schema to explicitly allow only
420MHz like this?

link-frequencies:
  items:
  - const: 420000000

Best Regards,
Hardev