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 08:36:19 +0100
From:   "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.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 <linux-media@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>,
        LAK <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v5 2/5] media: i2c: ov5645: Drop reading clock-frequency dt-property

Hi Laurent,

Thank you for the review.

On Mon, Apr 6, 2020 at 6:34 PM Laurent Pinchart
<laurent.pinchart@...asonboard.com> wrote:
>
> Hi Prabhakar,
>
> Thank you for the patch.
>
> On Mon, Apr 06, 2020 at 05:42:38PM +0100, Lad Prabhakar 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>
> > ---
> >  drivers/media/i2c/ov5645.c | 14 +++++---------
> >  1 file changed, 5 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/media/i2c/ov5645.c b/drivers/media/i2c/ov5645.c
> > index a6c17d15d754..52848fff8a08 100644
> > --- 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
> > +
> >  /* regulator supplies */
> >  static const char * const ov5645_supply_name[] = {
> >       "vdddo", /* Digital I/O (1.8V) supply */
> > @@ -1094,25 +1096,19 @@ static int ov5645_probe(struct i2c_client *client)
> >               return PTR_ERR(ov5645->xclk);
> >       }
> >
> > -     ret = of_property_read_u32(dev->of_node, "clock-frequency", &xclk_freq);
> > +     ret = clk_set_rate(ov5645->xclk, OV5645_XVCLK_FREQ);
> >       if (ret) {
> > -             dev_err(dev, "could not get xclk frequency\n");
> > +             dev_err(dev, "could not set xclk frequency\n");
> >               return ret;
> >       }
> > -
>
> I think you can keep the blank line here.
>
Oops my bad will drop that in next version.

Cheers,
--Prabhakar

> Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
>
> >       /* external clock must be 24MHz, allow 1% tolerance */
> > +     xclk_freq = clk_get_rate(ov5645->xclk);
> >       if (xclk_freq < 23760000 || xclk_freq > 24240000) {
> >               dev_err(dev, "external clock frequency %u is not supported\n",
> >                       xclk_freq);
> >               return -EINVAL;
> >       }
> >
> > -     ret = clk_set_rate(ov5645->xclk, xclk_freq);
> > -     if (ret) {
> > -             dev_err(dev, "could not set xclk frequency\n");
> > -             return ret;
> > -     }
> > -
> >       for (i = 0; i < OV5645_NUM_SUPPLIES; i++)
> >               ov5645->supplies[i].supply = ov5645_supply_name[i];
> >
>
> --
> Regards,
>
> Laurent Pinchart