linux-kernel - RE: [PATCH 2/2] media: i2c: ov5645: Switch to assigned-clock-rates

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Date:   Tue, 10 Mar 2020 08:57:42 +0000
From:   Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>
To:     Sakari Ailus <sakari.ailus@...ux.intel.com>
CC:     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>,
        "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>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Lad Prabhakar <prabhakar.csengg@...il.com>
Subject: RE: [PATCH 2/2] media: i2c: ov5645: Switch to assigned-clock-rates

Hi Sakari,

Thank you for the review.

> -----Original Message-----
> From: Sakari Ailus <sakari.ailus@...ux.intel.com>
> Sent: 10 March 2020 08:50
> To: Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>
> Cc: 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>; linux-
> media@...r.kernel.org; devicetree@...r.kernel.org; linux-
> kernel@...r.kernel.org; linux-arm-kernel@...ts.infradead.org; Lad
> Prabhakar <prabhakar.csengg@...il.com>
> Subject: Re: [PATCH 2/2] media: i2c: ov5645: Switch to assigned-clock-rates
>
> Hi Prabhakar,
>
> On Mon, Mar 09, 2020 at 11:46:13AM +0000, Lad Prabhakar wrote:
> > This patch switches to assigned-clock-rates for specifying the clock rate.
> > The clk-conf.c internally handles setting the clock rate, as a result
> > setting the clk rate from the driver is dropped.
> >
> > Correspondingly imx6qdl-wandboard.dtsi which references to ov5645 has
> > been updated to use assigned-clock-rates in the same patch to avoid
> > bisect failures.
> >
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-
> lad.rj@...renesas.com>
> > ---
> >  arch/arm/boot/dts/imx6qdl-wandboard.dtsi | 3 ++-
> >  drivers/media/i2c/ov5645.c               | 9 ++-------
> >  2 files changed, 4 insertions(+), 8 deletions(-)
> >
> > diff --git a/arch/arm/boot/dts/imx6qdl-wandboard.dtsi
> > b/arch/arm/boot/dts/imx6qdl-wandboard.dtsi
> > index c070893..71f5f75 100644
> > --- a/arch/arm/boot/dts/imx6qdl-wandboard.dtsi
> > +++ b/arch/arm/boot/dts/imx6qdl-wandboard.dtsi
> > @@ -126,7 +126,8 @@
> >  reg = <0x3c>;
> >  clocks = <&clks IMX6QDL_CLK_CKO2>;
> >  clock-names = "xclk";
> > -clock-frequency = <24000000>;
> > +assigned-clocks = <&clks IMX6QDL_CLK_CKO2>;
> > +assigned-clock-rates = <24000000>;
> >  vdddo-supply = <&reg_1p8v>;
> >  vdda-supply = <&reg_2p8v>;
> >  vddd-supply = <&reg_1p5v>;
>
> Shouldn't this be a separate patch?
>
I did think about it, but realized it might break bisect, but with below changes this can
be a separate patch now.

> > diff --git a/drivers/media/i2c/ov5645.c b/drivers/media/i2c/ov5645.c
> > index a6c17d1..2aa2677 100644
> > --- a/drivers/media/i2c/ov5645.c
> > +++ b/drivers/media/i2c/ov5645.c
> > @@ -1094,7 +1094,8 @@ 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 = of_property_read_u32(dev->of_node, "assigned-clock-rates",
> > +   &xclk_freq);
>
> I think you'd still need to check for clock-frequency to be compatible with
> existing DT binaries.
>
Makes sense, I will add the check for it and if clock-frequency is specified Ill let the driver
set the clock.

Cheers,
--Prabhakar

> >  if (ret) {
> >  dev_err(dev, "could not get xclk frequency\n");
> >  return ret;
> > @@ -1107,12 +1108,6 @@ static int ov5645_probe(struct i2c_client *client)
> >  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,
>
> Sakari Ailus


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