linux-kernel - Re: [PATCH v5 2/5] media: i2c: ov5645: Drop reading clock-frequency dt-property

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Date:   Tue, 7 Apr 2020 08:40:06 +0100
From:   "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v5 2/5] media: i2c: ov5645: Drop reading clock-frequency dt-property

Hi Geert,

Thank you for the review.

On Tue, Apr 7, 2020 at 8:17 AM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>
> Hi Prabhakar,
>
> On Mon, Apr 6, 2020 at 6:43 PM Lad Prabhakar
> <prabhakar.mahadev-lad.rj@...renesas.com> wrote:
> > Modes in the driver are based on xvclk frequency fixed to 24MHz, but where
> > as the OV5645 sensor can support the xvclk frequency ranging from 6MHz to
> > 24MHz. So instead making clock-frequency as dt-property just let the
> > driver enforce the required clock frequency.
> >
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
>
> Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>
>
> However, still wondering about the "xvclk" name above and in the definition
> below.  Is this the naming from the datasheet?
> The DT bindings nor the driver use the "xvclk" naming.
>
xvclk naming is from the datasheet, although the 0v5645 datasheet on
publicly available I have referred [1]/[2].
If I am not wrong all the ov sensors have the same naming convention as xvclk.

[1] https://cdn.sparkfun.com/datasheets/Sensors/LightImaging/OV5640_datasheet.pdf
[2] https://www.ovt.com/download/sensorpdf/126/OmniVision_OV5645.pdf

Cheers,
--Prabhakar

> > --- a/drivers/media/i2c/ov5645.c
> > +++ b/drivers/media/i2c/ov5645.c
> > @@ -61,6 +61,8 @@
> >  #define OV5645_SDE_SAT_U               0x5583
> >  #define OV5645_SDE_SAT_V               0x5584
> >
> > +#define OV5645_XVCLK_FREQ              24000000
> > +
>
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds