[PATCH v2 0/3] ov5645: Switch to assigned-clock-rates

[PATCH v2 0/3] ov5645: Switch to assigned-clock-rates

[Lad Prabhakar]

Hi All,

This patch series adds support for using assigned-clock-rates for
specifying clock rates for ov5645 driver

Thanks,
Prabhakar

Changes for V2:
* Instead of completely dropping clock-frequency property marked it as
  deprecated.
* Split up imx6qdl-wandboard.dtsi changes as separate patch.


Lad Prabhakar (3):
  media: dt-bindings: media: i2c: Switch to assigned-clock-rates
  media: i2c: ov5645: Switch to assigned-clock-rates
  ARM: dts: imx6qdl-wandboard: Switch to assigned-clock-rates for ov5645
    node

 .../devicetree/bindings/media/i2c/ov5645.txt       |  5 +++--
 arch/arm/boot/dts/imx6qdl-wandboard.dtsi           |  3 ++-
 drivers/media/i2c/ov5645.c                         | 24 +++++++++++++++-------
 3 files changed, 22 insertions(+), 10 deletions(-)

-- 
2.7.4

[PATCH v2 1/3] media: dt-bindings: media: i2c: Switch to assigned-clock-rates

[Lad Prabhakar]

Use assigned-clock-rates to specify the clock rate. Also mark
clock-frequency property as deprecated.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
---
 Documentation/devicetree/bindings/media/i2c/ov5645.txt | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/media/i2c/ov5645.txt b/Documentation/devicetree/bindings/media/i2c/ov5645.txt
index 72ad992..e62fe82 100644
--- a/Documentation/devicetree/bindings/media/i2c/ov5645.txt
+++ b/Documentation/devicetree/bindings/media/i2c/ov5645.txt
@@ -8,7 +8,7 @@ Required Properties:
 - compatible: Value should be "ovti,ov5645".
 - clocks: Reference to the xclk clock.
 - clock-names: Should be "xclk".
-- clock-frequency: Frequency of the xclk clock.
+- clock-frequency (deprecated): Frequency of the xclk clock.
 - enable-gpios: Chip enable GPIO. Polarity is GPIO_ACTIVE_HIGH. This corresponds
   to the hardware pin PWDNB which is physically active low.
 - reset-gpios: Chip reset GPIO. Polarity is GPIO_ACTIVE_LOW. This corresponds to
@@ -37,7 +37,8 @@ Example:
 
 			clocks = <&clks 200>;
 			clock-names = "xclk";
-			clock-frequency = <24000000>;
+			assigned-clocks = <&clks 200>;
+			assigned-clock-rates = <24000000>;
 
 			vdddo-supply = <&camera_dovdd_1v8>;
 			vdda-supply = <&camera_avdd_2v8>;
-- 
2.7.4

[PATCH v2 2/3] media: i2c: ov5645: Switch to assigned-clock-rates

[Lad Prabhakar]

This patch switches to assigned-clock-rates for specifying the clock rate.
The clk-conf.c internally handles setting the clock rate when
assigned-clock-rates is passed.

The driver now sets the clock frequency only if the deprecated property
clock-frequency is defined instead assigned-clock-rates, this is to avoid
breakage with existing DT binaries.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
---
 drivers/media/i2c/ov5645.c | 24 +++++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/drivers/media/i2c/ov5645.c b/drivers/media/i2c/ov5645.c
index a6c17d1..6cd16c5 100644
--- a/drivers/media/i2c/ov5645.c
+++ b/drivers/media/i2c/ov5645.c
@@ -1055,6 +1055,7 @@ static int ov5645_probe(struct i2c_client *client)
 	struct device_node *endpoint;
 	struct ov5645 *ov5645;
 	u8 chip_id_high, chip_id_low;
+	bool set_clk = false;
 	unsigned int i;
 	u32 xclk_freq;
 	int ret;
@@ -1094,10 +1095,17 @@ 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);
 	if (ret) {
-		dev_err(dev, "could not get xclk frequency\n");
-		return ret;
+		/* check if deprecated property clock-frequency is defined */
+		ret = of_property_read_u32(dev->of_node, "clock-frequency",
+					   &xclk_freq);
+		if (ret) {
+			dev_err(dev, "could not get xclk frequency\n");
+			return ret;
+		}
+		set_clk = true;
 	}
 
 	/* external clock must be 24MHz, allow 1% tolerance */
@@ -1107,10 +1115,12 @@ 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;
+	if (set_clk) {
+		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++)
-- 
2.7.4

[PATCH v2 3/3] ARM: dts: imx6qdl-wandboard: Switch to assigned-clock-rates for ov5645 node

[Lad Prabhakar]

clock-frequency property is now marked as deprecated in ov5645 binding,
so switch to assigned-clock-rates for specifying xclk clock frequency.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
---
 arch/arm/boot/dts/imx6qdl-wandboard.dtsi | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

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>;
-- 
2.7.4

Re: [PATCH v2 2/3] media: i2c: ov5645: Switch to assigned-clock-rates

[Geert Uytterhoeven]

Hi Prabhakar,

On Thu, Mar 12, 2020 at 10:13 PM Lad Prabhakar
<prabhakar.mahadev-lad.rj@bp.renesas.com> wrote:
> This patch switches to assigned-clock-rates for specifying the clock rate.
> The clk-conf.c internally handles setting the clock rate when
> assigned-clock-rates is passed.
>
> The driver now sets the clock frequency only if the deprecated property
> clock-frequency is defined instead assigned-clock-rates, this is to avoid
> breakage with existing DT binaries.
>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>

Thanks for your patch!

> --- a/drivers/media/i2c/ov5645.c
> +++ b/drivers/media/i2c/ov5645.c
> @@ -1055,6 +1055,7 @@ static int ov5645_probe(struct i2c_client *client)
>         struct device_node *endpoint;
>         struct ov5645 *ov5645;
>         u8 chip_id_high, chip_id_low;
> +       bool set_clk = false;
>         unsigned int i;
>         u32 xclk_freq;
>         int ret;
> @@ -1094,10 +1095,17 @@ 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);
>         if (ret) {

I think you can just leave out the above check...

> -               dev_err(dev, "could not get xclk frequency\n");
> -               return ret;
> +               /* check if deprecated property clock-frequency is defined */
> +               ret = of_property_read_u32(dev->of_node, "clock-frequency",
> +                                          &xclk_freq);
> +               if (ret) {

... and ignore the absence of the deprecated property.

> +                       dev_err(dev, "could not get xclk frequency\n");
> +                       return ret;
> +               }
> +               set_clk = true;

I.e. just

        /* check if deprecated property clock-frequency is defined */
        xclk_freq = 0;
        of_property_read_u32(dev->of_node, "clock-frequency", &xclk_freq);
        if (xclk_freq) {
                ret = clk_set_rate(ov5645->xclk, xclk_freq);
                if (ret) {
                        dev_err(dev, "could not set xclk frequency\n");
                        return ret;
                }
        } else {
                xclk_freq = clk_get_rate(ov5645->xclk, xclk_freq);
        }

>         }
>
>         /* external clock must be 24MHz, allow 1% tolerance */
> @@ -1107,10 +1115,12 @@ 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;
> +       if (set_clk) {
> +               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++)
> --
> 2.7.4
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel



-- 
Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-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

RE: [PATCH v2 2/3] media: i2c: ov5645: Switch to assigned-clock-rates

[Prabhakar Mahadev Lad]

Hi Geert,

Thank you for the quick review.

> -----Original Message-----
> From: Geert Uytterhoeven <geert@linux-m68k.org>
> Sent: 12 March 2020 21:42
> To: Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@bp.renesas.com>
> Cc: Mauro Carvalho Chehab <mchehab@kernel.org>; Shawn Guo
> <shawnguo@kernel.org>; Sascha Hauer <s.hauer@pengutronix.de>;
> Pengutronix Kernel Team <kernel@pengutronix.de>; Rob Herring
> <robh+dt@kernel.org>; Mark Rutland <mark.rutland@arm.com>; Sakari
> Ailus <sakari.ailus@linux.intel.com>; NXP Linux Team <linux-imx@nxp.com>;
> Magnus Damm <magnus.damm@gmail.com>; Ezequiel Garcia
> <ezequiel@collabora.com>; open list:OPEN FIRMWARE AND FLATTENED
> DEVICE TREE BINDINGS <devicetree@vger.kernel.org>; Linux Kernel Mailing
> List <linux-kernel@vger.kernel.org>; Linux-Renesas <linux-renesas-
> soc@vger.kernel.org>; Fabio Estevam <festevam@gmail.com>; Linux ARM
> <linux-arm-kernel@lists.infradead.org>; Linux Media Mailing List <linux-
> media@vger.kernel.org>
> Subject: Re: [PATCH v2 2/3] media: i2c: ov5645: Switch to assigned-clock-
> rates
>
> Hi Prabhakar,
>
> On Thu, Mar 12, 2020 at 10:13 PM Lad Prabhakar <prabhakar.mahadev-
> lad.rj@bp.renesas.com> wrote:
> > This patch switches to assigned-clock-rates for specifying the clock rate.
> > The clk-conf.c internally handles setting the clock rate when
> > assigned-clock-rates is passed.
> >
> > The driver now sets the clock frequency only if the deprecated
> > property clock-frequency is defined instead assigned-clock-rates, this
> > is to avoid breakage with existing DT binaries.
> >
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-
> lad.rj@bp.renesas.com>
>
> Thanks for your patch!
>
> > --- a/drivers/media/i2c/ov5645.c
> > +++ b/drivers/media/i2c/ov5645.c
> > @@ -1055,6 +1055,7 @@ static int ov5645_probe(struct i2c_client *client)
> >         struct device_node *endpoint;
> >         struct ov5645 *ov5645;
> >         u8 chip_id_high, chip_id_low;
> > +       bool set_clk = false;
> >         unsigned int i;
> >         u32 xclk_freq;
> >         int ret;
> > @@ -1094,10 +1095,17 @@ 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);
> >         if (ret) {
>
> I think you can just leave out the above check...
>
> > -               dev_err(dev, "could not get xclk frequency\n");
> > -               return ret;
> > +               /* check if deprecated property clock-frequency is defined */
> > +               ret = of_property_read_u32(dev->of_node, "clock-frequency",
> > +                                          &xclk_freq);
> > +               if (ret) {
>
> ... and ignore the absence of the deprecated property.
>
> > +                       dev_err(dev, "could not get xclk frequency\n");
> > +                       return ret;
> > +               }
> > +               set_clk = true;
>
> I.e. just
>
>         /* check if deprecated property clock-frequency is defined */
>         xclk_freq = 0;
>         of_property_read_u32(dev->of_node, "clock-frequency", &xclk_freq);
>         if (xclk_freq) {
>                 ret = clk_set_rate(ov5645->xclk, xclk_freq);
>                 if (ret) {
>                         dev_err(dev, "could not set xclk frequency\n");
>                         return ret;
>                 }
>         } else {
>                 xclk_freq = clk_get_rate(ov5645->xclk, xclk_freq);
>         }
>
I did think about it initially, but realized the clk_get_rate may vary platform to platform
for example in G2E clk_get_rate() returns a frequency of 24242424 with
assigned-clock-rates set to  24000000 and probe would fail due to a check for
external clock must be 24MHz, with 1% tolerance.

Cheers,
--Prabhakar

> >         }
> >
> >         /* external clock must be 24MHz, allow 1% tolerance */ @@
> > -1107,10 +1115,12 @@ 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;
> > +       if (set_clk) {
> > +               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++)
> > --
> > 2.7.4
> >
> >
> > _______________________________________________
> > linux-arm-kernel mailing list
> > linux-arm-kernel@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
>
>
> --
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-
> 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


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Re: [PATCH v2 2/3] media: i2c: ov5645: Switch to assigned-clock-rates

[Laurent Pinchart]

Hi Prabakhar,

Thank you for the patch.

On Thu, Mar 12, 2020 at 09:12:31PM +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 when
> assigned-clock-rates is passed.
> 
> The driver now sets the clock frequency only if the deprecated property
> clock-frequency is defined instead assigned-clock-rates, this is to avoid
> breakage with existing DT binaries.
> 
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> ---
>  drivers/media/i2c/ov5645.c | 24 +++++++++++++++++-------
>  1 file changed, 17 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/media/i2c/ov5645.c b/drivers/media/i2c/ov5645.c
> index a6c17d1..6cd16c5 100644
> --- a/drivers/media/i2c/ov5645.c
> +++ b/drivers/media/i2c/ov5645.c
> @@ -1055,6 +1055,7 @@ static int ov5645_probe(struct i2c_client *client)
>  	struct device_node *endpoint;
>  	struct ov5645 *ov5645;
>  	u8 chip_id_high, chip_id_low;
> +	bool set_clk = false;
>  	unsigned int i;
>  	u32 xclk_freq;
>  	int ret;
> @@ -1094,10 +1095,17 @@ 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);

You shouldn't read the assigned-clock-rates property, you should instead
get the rate from the clock with clk_get_rate().

>  	if (ret) {
> -		dev_err(dev, "could not get xclk frequency\n");
> -		return ret;
> +		/* check if deprecated property clock-frequency is defined */
> +		ret = of_property_read_u32(dev->of_node, "clock-frequency",
> +					   &xclk_freq);
> +		if (ret) {
> +			dev_err(dev, "could not get xclk frequency\n");
> +			return ret;
> +		}
> +		set_clk = true;
>  	}
>  
>  	/* external clock must be 24MHz, allow 1% tolerance */
> @@ -1107,10 +1115,12 @@ 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;
> +	if (set_clk) {
> +		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++)

-- 
Regards,

Laurent Pinchart

Re: [PATCH v2 2/3] media: i2c: ov5645: Switch to assigned-clock-rates

[Laurent Pinchart]

Hi Prabhakar,

On Thu, Mar 12, 2020 at 09:52:38PM +0000, Prabhakar Mahadev Lad wrote:
> On 12 March 2020 21:42, Geert Uytterhoeven wrote:
> > On Thu, Mar 12, 2020 at 10:13 PM 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 when
> > > assigned-clock-rates is passed.
> > >
> > > The driver now sets the clock frequency only if the deprecated
> > > property clock-frequency is defined instead assigned-clock-rates, this
> > > is to avoid breakage with existing DT binaries.
> > >
> > > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> >
> > Thanks for your patch!
> >
> > > --- a/drivers/media/i2c/ov5645.c
> > > +++ b/drivers/media/i2c/ov5645.c
> > > @@ -1055,6 +1055,7 @@ static int ov5645_probe(struct i2c_client *client)
> > >         struct device_node *endpoint;
> > >         struct ov5645 *ov5645;
> > >         u8 chip_id_high, chip_id_low;
> > > +       bool set_clk = false;
> > >         unsigned int i;
> > >         u32 xclk_freq;
> > >         int ret;
> > > @@ -1094,10 +1095,17 @@ 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);
> > >         if (ret) {
> >
> > I think you can just leave out the above check...
> >
> > > -               dev_err(dev, "could not get xclk frequency\n");
> > > -               return ret;
> > > +               /* check if deprecated property clock-frequency is defined */
> > > +               ret = of_property_read_u32(dev->of_node, "clock-frequency",
> > > +                                          &xclk_freq);
> > > +               if (ret) {
> >
> > ... and ignore the absence of the deprecated property.
> >
> > > +                       dev_err(dev, "could not get xclk frequency\n");
> > > +                       return ret;
> > > +               }
> > > +               set_clk = true;
> >
> > I.e. just
> >
> >         /* check if deprecated property clock-frequency is defined */
> >         xclk_freq = 0;
> >         of_property_read_u32(dev->of_node, "clock-frequency", &xclk_freq);
> >         if (xclk_freq) {
> >                 ret = clk_set_rate(ov5645->xclk, xclk_freq);
> >                 if (ret) {
> >                         dev_err(dev, "could not set xclk frequency\n");
> >                         return ret;
> >                 }
> >         } else {
> >                 xclk_freq = clk_get_rate(ov5645->xclk, xclk_freq);
> >         }
> >
> I did think about it initially, but realized the clk_get_rate may vary platform to platform
> for example in G2E clk_get_rate() returns a frequency of 24242424 with
> assigned-clock-rates set to  24000000 and probe would fail due to a check for
> external clock must be 24MHz, with 1% tolerance.

Then you need to handle the tolerance in this driver :-)

> > >         }
> > >
> > >         /* external clock must be 24MHz, allow 1% tolerance */ @@
> > > -1107,10 +1115,12 @@ 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;
> > > +       if (set_clk) {
> > > +               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++)

-- 
Regards,

Laurent Pinchart

RE: [PATCH v2 2/3] media: i2c: ov5645: Switch to assigned-clock-rates

[Prabhakar Mahadev Lad]

Hi Laurent,

Thank you for the review.

> -----Original Message-----
> From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Sent: 12 March 2020 23:03
> To: Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@bp.renesas.com>
> Cc: Geert Uytterhoeven <geert@linux-m68k.org>; Mauro Carvalho Chehab
> <mchehab@kernel.org>; Shawn Guo <shawnguo@kernel.org>; Sascha
> Hauer <s.hauer@pengutronix.de>; Pengutronix Kernel Team
> <kernel@pengutronix.de>; Rob Herring <robh+dt@kernel.org>; Mark
> Rutland <mark.rutland@arm.com>; Sakari Ailus
> <sakari.ailus@linux.intel.com>; NXP Linux Team <linux-imx@nxp.com>;
> Magnus Damm <magnus.damm@gmail.com>; Ezequiel Garcia
> <ezequiel@collabora.com>; open list:OPEN FIRMWARE AND FLATTENED
> DEVICE TREE BINDINGS <devicetree@vger.kernel.org>; Linux Kernel Mailing
> List <linux-kernel@vger.kernel.org>; Linux-Renesas <linux-renesas-
> soc@vger.kernel.org>; Fabio Estevam <festevam@gmail.com>; Linux ARM
> <linux-arm-kernel@lists.infradead.org>; Linux Media Mailing List <linux-
> media@vger.kernel.org>
> Subject: Re: [PATCH v2 2/3] media: i2c: ov5645: Switch to assigned-clock-
> rates
>
> Hi Prabhakar,
>
> On Thu, Mar 12, 2020 at 09:52:38PM +0000, Prabhakar Mahadev Lad wrote:
> > On 12 March 2020 21:42, Geert Uytterhoeven wrote:
> > > On Thu, Mar 12, 2020 at 10:13 PM 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 when
> > > > assigned-clock-rates is passed.
> > > >
> > > > The driver now sets the clock frequency only if the deprecated
> > > > property clock-frequency is defined instead assigned-clock-rates,
> > > > this is to avoid breakage with existing DT binaries.
> > > >
> > > > Signed-off-by: Lad Prabhakar
> > > > <prabhakar.mahadev-lad.rj@bp.renesas.com>
> > >
> > > Thanks for your patch!
> > >
> > > > --- a/drivers/media/i2c/ov5645.c
> > > > +++ b/drivers/media/i2c/ov5645.c
> > > > @@ -1055,6 +1055,7 @@ static int ov5645_probe(struct i2c_client
> *client)
> > > >         struct device_node *endpoint;
> > > >         struct ov5645 *ov5645;
> > > >         u8 chip_id_high, chip_id_low;
> > > > +       bool set_clk = false;
> > > >         unsigned int i;
> > > >         u32 xclk_freq;
> > > >         int ret;
> > > > @@ -1094,10 +1095,17 @@ 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);
> > > >         if (ret) {
> > >
> > > I think you can just leave out the above check...
> > >
> > > > -               dev_err(dev, "could not get xclk frequency\n");
> > > > -               return ret;
> > > > +               /* check if deprecated property clock-frequency is defined */
> > > > +               ret = of_property_read_u32(dev->of_node, "clock-
> frequency",
> > > > +                                          &xclk_freq);
> > > > +               if (ret) {
> > >
> > > ... and ignore the absence of the deprecated property.
> > >
> > > > +                       dev_err(dev, "could not get xclk frequency\n");
> > > > +                       return ret;
> > > > +               }
> > > > +               set_clk = true;
> > >
> > > I.e. just
> > >
> > >         /* check if deprecated property clock-frequency is defined */
> > >         xclk_freq = 0;
> > >         of_property_read_u32(dev->of_node, "clock-frequency",
> &xclk_freq);
> > >         if (xclk_freq) {
> > >                 ret = clk_set_rate(ov5645->xclk, xclk_freq);
> > >                 if (ret) {
> > >                         dev_err(dev, "could not set xclk frequency\n");
> > >                         return ret;
> > >                 }
> > >         } else {
> > >                 xclk_freq = clk_get_rate(ov5645->xclk, xclk_freq);
> > >         }
> > >
> > I did think about it initially, but realized the clk_get_rate may vary
> > platform to platform for example in G2E clk_get_rate() returns a
> > frequency of 24242424 with assigned-clock-rates set to  24000000 and
> > probe would fail due to a check for external clock must be 24MHz, with 1%
> tolerance.
>
> Then you need to handle the tolerance in this driver :-)
>
Sure I will increase the tolerance here.

Cheers,
--Prabhakar

> > > >         }
> > > >
> > > >         /* external clock must be 24MHz, allow 1% tolerance */ @@
> > > > -1107,10 +1115,12 @@ 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;
> > > > +       if (set_clk) {
> > > > +               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++)
>
> --
> Regards,
>
> Laurent Pinchart


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