[PATCH v3 0/4] ov5645: Switch to assigned-clock-rates

[PATCH v3 0/4] 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

Changed for v3:
* Dropped reading assigned-clock-rates
* Increased the maximum clock frequency to 24480000

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 (4):
  media: dt-bindings: media: i2c: Switch to assigned-clock-rates
  media: i2c: ov5645: Switch to assigned-clock-rates
  media: i2c: ov5645: Set maximum leverage of external clock frequency
    to 24480000
  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                         | 27 ++++++++++++----------
 3 files changed, 20 insertions(+), 15 deletions(-)

-- 
2.7.4


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[PATCH v3 1/4] 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


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[PATCH v3 2/4] 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 | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/drivers/media/i2c/ov5645.c b/drivers/media/i2c/ov5645.c
index a6c17d1..4fbabf3 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;
@@ -1094,12 +1095,18 @@ 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);
-	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) {
+		ret = clk_set_rate(ov5645->xclk, xclk_freq);
+		if (ret) {
+			dev_err(dev, "could not set xclk frequency\n");
+			return ret;
+		}
 	}
 
+	xclk_freq = clk_get_rate(ov5645->xclk);
 	/* external clock must be 24MHz, allow 1% tolerance */
 	if (xclk_freq < 23760000 || xclk_freq > 24240000) {
 		dev_err(dev, "external clock frequency %u is not supported\n",
@@ -1107,12 +1114,6 @@ 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];
 
-- 
2.7.4


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[PATCH v3 3/4] media: i2c: ov5645: Set maximum leverage of external clock frequency to 24480000

[Lad Prabhakar]

While testing on Renesas RZ/G2E platform, noticed the clock frequency to
be 24242424 as a result the probe failed. However increasing the maximum
leverage of external clock frequency to 24480000 fixes this issue. Since
this difference is small enough and is insignificant set the same in the
driver.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
---
 drivers/media/i2c/ov5645.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/media/i2c/ov5645.c b/drivers/media/i2c/ov5645.c
index 4fbabf3..b49359b 100644
--- a/drivers/media/i2c/ov5645.c
+++ b/drivers/media/i2c/ov5645.c
@@ -1107,8 +1107,10 @@ static int ov5645_probe(struct i2c_client *client)
 	}
 
 	xclk_freq = clk_get_rate(ov5645->xclk);
-	/* external clock must be 24MHz, allow 1% tolerance */
-	if (xclk_freq < 23760000 || xclk_freq > 24240000) {
+	/* external clock must be 24MHz, allow a minimum 1% and a maximum of 2%
+	 * tolerance
+	 */
+	if (xclk_freq < 23760000 || xclk_freq > 24480000) {
 		dev_err(dev, "external clock frequency %u is not supported\n",
 			xclk_freq);
 		return -EINVAL;
-- 
2.7.4


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[PATCH v3 4/4] 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


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Re: [PATCH v3 2/4] media: i2c: ov5645: Switch to assigned-clock-rates

[Laurent Pinchart]

Hi Prabakhar,

Thank you for the patch.

On Fri, Mar 13, 2020 at 09:12:32PM +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 | 21 +++++++++++----------
>  1 file changed, 11 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/media/i2c/ov5645.c b/drivers/media/i2c/ov5645.c
> index a6c17d1..4fbabf3 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;

This isn't used.

>  	unsigned int i;
>  	u32 xclk_freq;
>  	int ret;
> @@ -1094,12 +1095,18 @@ 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);
> -	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) {
> +		ret = clk_set_rate(ov5645->xclk, xclk_freq);
> +		if (ret) {
> +			dev_err(dev, "could not set xclk frequency\n");
> +			return ret;
> +		}
>  	}
>  
> +	xclk_freq = clk_get_rate(ov5645->xclk);

I would move this line below the comment.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

>  	/* external clock must be 24MHz, allow 1% tolerance */
>  	if (xclk_freq < 23760000 || xclk_freq > 24240000) {
>  		dev_err(dev, "external clock frequency %u is not supported\n",
> @@ -1107,12 +1114,6 @@ 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,

Laurent Pinchart

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RE: [PATCH v3 2/4] media: i2c: ov5645: Switch to assigned-clock-rates

[Prabhakar Mahadev Lad]

Hi Laurent,

Thank you for the quick review.

> -----Original Message-----
> From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Sent: 13 March 2020 21:17
> 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>; Geert Uytterhoeven <geert@linux-m68k.org>;
> devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; linux-renesas-
> soc@vger.kernel.org; Fabio Estevam <festevam@gmail.com>; linux-
> media@vger.kernel.org; linux-arm-kernel@lists.infradead.org
> Subject: Re: [PATCH v3 2/4] media: i2c: ov5645: Switch to assigned-clock-
> rates
>
> Hi Prabakhar,
>
> Thank you for the patch.
>
> On Fri, Mar 13, 2020 at 09:12:32PM +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 | 21 +++++++++++----------
> >  1 file changed, 11 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/media/i2c/ov5645.c b/drivers/media/i2c/ov5645.c
> > index a6c17d1..4fbabf3 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;
>
> This isn't used.
>
Argh! missed it.

> >  unsigned int i;
> >  u32 xclk_freq;
> >  int ret;
> > @@ -1094,12 +1095,18 @@ 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);
> > -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) {
> > +ret = clk_set_rate(ov5645->xclk, xclk_freq);
> > +if (ret) {
> > +dev_err(dev, "could not set xclk frequency\n");
> > +return ret;
> > +}
> >  }
> >
> > +xclk_freq = clk_get_rate(ov5645->xclk);
>
> I would move this line below the comment.
>
Sure will do that.

Cheers,
--Prabhakar

> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
>
> >  /* external clock must be 24MHz, allow 1% tolerance */
> >  if (xclk_freq < 23760000 || xclk_freq > 24240000) {
> >  dev_err(dev, "external clock frequency %u is not
> supported\n", @@
> > -1107,12 +1114,6 @@ 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,
>
> Laurent Pinchart


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Re: [PATCH v3 1/4] media: dt-bindings: media: i2c: Switch to assigned-clock-rates

[Laurent Pinchart]

Hi Prabhakar,

Thank you for the patch.

On Fri, Mar 13, 2020 at 09:12:31PM +0000, Lad Prabhakar wrote:
> Use assigned-clock-rates to specify the clock rate. Also mark
> clock-frequency property as deprecated.

I would phrase it the other way around, this patch mainly deprecates
clock-frequency, and as a side effect recommends usage of
assigned-clock-rates.

"Deprecate usage of the clock-frequency propertly. The preferred method
to set clock rates is to use assigned-clock-rates."

> 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.

I would drop this completely. Drivers need to ensure backward
compatibility, but DT bindings should only document the latest version,
the history is available in git.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

While at it, can I enlist you to convert these bindings to yaml ? :-)

>  - 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>;

-- 
Regards,

Laurent Pinchart

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Re: [PATCH v3 3/4] media: i2c: ov5645: Set maximum leverage of external clock frequency to 24480000

[Laurent Pinchart]

Hi Prabhakar,

Thank you for the patch.

On Fri, Mar 13, 2020 at 09:12:33PM +0000, Lad Prabhakar wrote:
> While testing on Renesas RZ/G2E platform, noticed the clock frequency to
> be 24242424 as a result the probe failed. However increasing the maximum
> leverage of external clock frequency to 24480000 fixes this issue. Since
> this difference is small enough and is insignificant set the same in the
> driver.
> 
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> ---
>  drivers/media/i2c/ov5645.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/i2c/ov5645.c b/drivers/media/i2c/ov5645.c
> index 4fbabf3..b49359b 100644
> --- a/drivers/media/i2c/ov5645.c
> +++ b/drivers/media/i2c/ov5645.c
> @@ -1107,8 +1107,10 @@ static int ov5645_probe(struct i2c_client *client)
>  	}
>  
>  	xclk_freq = clk_get_rate(ov5645->xclk);
> -	/* external clock must be 24MHz, allow 1% tolerance */
> -	if (xclk_freq < 23760000 || xclk_freq > 24240000) {
> +	/* external clock must be 24MHz, allow a minimum 1% and a maximum of 2%
> +	 * tolerance

So where do these numbers come from ? I understand that 2% is what you
need to make your clock fit in the range, but why -1%/+2% instead of
-2%/+2% ? And why not 2.5 or 3% ? The sensor datasheet documents the
range of supported xvclk frequencies to be 6MHz to 54MHz. I understand
that PLL parameters depend on the clock frequency, but could they be
calculated instead of hardcoded, to avoid requiring an exact 24MHz input
frequency ?

> +	 */
> +	if (xclk_freq < 23760000 || xclk_freq > 24480000) {
>  		dev_err(dev, "external clock frequency %u is not supported\n",
>  			xclk_freq);
>  		return -EINVAL;

-- 
Regards,

Laurent Pinchart

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RE: [PATCH v3 1/4] media: dt-bindings: media: i2c: Switch to assigned-clock-rates

[Prabhakar Mahadev Lad]

Hi Laurent,

Thank you for the quick review.

> -----Original Message-----
> From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Sent: 13 March 2020 21:20
> 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>; Geert Uytterhoeven <geert@linux-m68k.org>;
> devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; linux-renesas-
> soc@vger.kernel.org; Fabio Estevam <festevam@gmail.com>; linux-
> media@vger.kernel.org; linux-arm-kernel@lists.infradead.org
> Subject: Re: [PATCH v3 1/4] media: dt-bindings: media: i2c: Switch to
> assigned-clock-rates
>
> Hi Prabhakar,
>
> Thank you for the patch.
>
> On Fri, Mar 13, 2020 at 09:12:31PM +0000, Lad Prabhakar wrote:
> > Use assigned-clock-rates to specify the clock rate. Also mark
> > clock-frequency property as deprecated.
>
> I would phrase it the other way around, this patch mainly deprecates clock-
> frequency, and as a side effect recommends usage of assigned-clock-rates.
>
> "Deprecate usage of the clock-frequency propertly. The preferred method
> to set clock rates is to use assigned-clock-rates."
>
Agreed will do that.

> > 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.
>
> I would drop this completely. Drivers need to ensure backward compatibility,
> but DT bindings should only document the latest version, the history is
> available in git.
>
Sure will drop it.

> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
>
> While at it, can I enlist you to convert these bindings to yaml ? :-)
>
Sure will do the honours 😊, will make sure yaml patch is ontop of this patch too.

Cheers,
--Prabhakar

> >  - 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>;
>
> --
> Regards,
>
> Laurent Pinchart


Renesas Electronics Europe GmbH, Geschaeftsfuehrer/President: Carsten Jauch, Sitz der Gesellschaft/Registered office: Duesseldorf, Arcadiastrasse 10, 40472 Duesseldorf, Germany, Handelsregister/Commercial Register: Duesseldorf, HRB 3708 USt-IDNr./Tax identification no.: DE 119353406 WEEE-Reg.-Nr./WEEE reg. no.: DE 14978647
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Re: [PATCH v3 4/4] ARM: dts: imx6qdl-wandboard: Switch to assigned-clock-rates for ov5645 node

[Laurent Pinchart]

Hi Prabhakar,

Thank you for the patch.

On Fri, Mar 13, 2020 at 09:12:34PM +0000, Lad Prabhakar wrote:
> clock-frequency property is now marked as deprecated in ov5645 binding,

Maybe /is now marked as/has been/ to match the recommended change to the
bindings in my reply to 1/4 ?

> so switch to assigned-clock-rates for specifying xclk clock frequency.
> 
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.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>;

-- 
Regards,

Laurent Pinchart

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Re: [PATCH v3 1/4] media: dt-bindings: media: i2c: Switch to assigned-clock-rates

[Laurent Pinchart]

Hi Prabhakar,

On Fri, Mar 13, 2020 at 09:25:01PM +0000, Prabhakar Mahadev Lad wrote:
> On Sent: 13 March 2020 21:20, Laurent Pinchart wrote:
> > On Fri, Mar 13, 2020 at 09:12:31PM +0000, Lad Prabhakar wrote:
> > > Use assigned-clock-rates to specify the clock rate. Also mark
> > > clock-frequency property as deprecated.
> >
> > I would phrase it the other way around, this patch mainly deprecates clock-
> > frequency, and as a side effect recommends usage of assigned-clock-rates.
> >
> > "Deprecate usage of the clock-frequency propertly. The preferred method
> > to set clock rates is to use assigned-clock-rates."
>
> Agreed will do that.
> 
> > > 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.
> >
> > I would drop this completely. Drivers need to ensure backward compatibility,
> > but DT bindings should only document the latest version, the history is
> > available in git.
> >
> Sure will drop it.
> 
> > Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> >
> > While at it, can I enlist you to convert these bindings to yaml ? :-)
> >
> Sure will do the honours 😊, will make sure yaml patch is ontop of this patch too.

Thank you :-)

> > >  - 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>;

-- 
Regards,

Laurent Pinchart

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RE: [PATCH v3 3/4] media: i2c: ov5645: Set maximum leverage of external clock frequency to 24480000

[Prabhakar Mahadev Lad]

Hi Laurent,

Thank you for the review.

> -----Original Message-----
> From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Sent: 13 March 2020 21:24
> 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>; Geert Uytterhoeven <geert@linux-m68k.org>;
> devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; linux-renesas-
> soc@vger.kernel.org; Fabio Estevam <festevam@gmail.com>; linux-
> media@vger.kernel.org; linux-arm-kernel@lists.infradead.org
> Subject: Re: [PATCH v3 3/4] media: i2c: ov5645: Set maximum leverage of
> external clock frequency to 24480000
>
> Hi Prabhakar,
>
> Thank you for the patch.
>
> On Fri, Mar 13, 2020 at 09:12:33PM +0000, Lad Prabhakar wrote:
> > While testing on Renesas RZ/G2E platform, noticed the clock frequency
> > to be 24242424 as a result the probe failed. However increasing the
> > maximum leverage of external clock frequency to 24480000 fixes this
> > issue. Since this difference is small enough and is insignificant set
> > the same in the driver.
> >
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-
> lad.rj@bp.renesas.com>
> > ---
> >  drivers/media/i2c/ov5645.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/media/i2c/ov5645.c b/drivers/media/i2c/ov5645.c
> > index 4fbabf3..b49359b 100644
> > --- a/drivers/media/i2c/ov5645.c
> > +++ b/drivers/media/i2c/ov5645.c
> > @@ -1107,8 +1107,10 @@ static int ov5645_probe(struct i2c_client *client)
> >  }
> >
> >  xclk_freq = clk_get_rate(ov5645->xclk);
> > -/* external clock must be 24MHz, allow 1% tolerance */
> > -if (xclk_freq < 23760000 || xclk_freq > 24240000) {
> > +/* external clock must be 24MHz, allow a minimum 1% and a
> maximum of 2%
> > + * tolerance
>
> So where do these numbers come from ? I understand that 2% is what you
> need to make your clock fit in the range, but why -1%/+2% instead of -
> 2%/+2% ? And why not 2.5 or 3% ? The sensor datasheet documents the
> range of supported xvclk frequencies to be 6MHz to 54MHz. I understand
> that PLL parameters depend on the clock frequency, but could they be
> calculated instead of hardcoded, to avoid requiring an exact 24MHz input
> frequency ?
>
To be honest I don't have the datasheet for ov5645, the flyer says 6-54Mhz but the
logs/comment says 24Mhz.

Cheers,
--Prabhakar

> > + */
> > +if (xclk_freq < 23760000 || xclk_freq > 24480000) {
> >  dev_err(dev, "external clock frequency %u is not
> supported\n",
> >  xclk_freq);
> >  return -EINVAL;
>
> --
> Regards,
>
> Laurent Pinchart


Renesas Electronics Europe GmbH, Geschaeftsfuehrer/President: Carsten Jauch, Sitz der Gesellschaft/Registered office: Duesseldorf, Arcadiastrasse 10, 40472 Duesseldorf, Germany, Handelsregister/Commercial Register: Duesseldorf, HRB 3708 USt-IDNr./Tax identification no.: DE 119353406 WEEE-Reg.-Nr./WEEE reg. no.: DE 14978647
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Re: [PATCH v3 1/4] media: dt-bindings: media: i2c: Switch to assigned-clock-rates

[Lad, Prabhakar]

Hi Laurent,

On Fri, Mar 13, 2020 at 9:27 PM Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
> Hi Prabhakar,
>
> On Fri, Mar 13, 2020 at 09:25:01PM +0000, Prabhakar Mahadev Lad wrote:
> > On Sent: 13 March 2020 21:20, Laurent Pinchart wrote:
> > > On Fri, Mar 13, 2020 at 09:12:31PM +0000, Lad Prabhakar wrote:
> > > > Use assigned-clock-rates to specify the clock rate. Also mark
> > > > clock-frequency property as deprecated.
> > >
> > > I would phrase it the other way around, this patch mainly deprecates clock-
> > > frequency, and as a side effect recommends usage of assigned-clock-rates.
> > >
> > > "Deprecate usage of the clock-frequency propertly. The preferred method
> > > to set clock rates is to use assigned-clock-rates."
> >
> > Agreed will do that.
> >
> > > > 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.
> > >
> > > I would drop this completely. Drivers need to ensure backward compatibility,
> > > but DT bindings should only document the latest version, the history is
> > > available in git.
> > >
> > Sure will drop it.
> >
> > > Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > >
> > > While at it, can I enlist you to convert these bindings to yaml ? :-)
> > >
> > Sure will do the honours , will make sure yaml patch is ontop of this patch too.
>
Shall I enlist you as the maintainer  in the json-schema ?
dt_binding_check says  'maintainers' is a required property.

Cheers,
--Prabhakar Lad

> Thank you :-)
>
> > > >  - 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>;
>
> --
> Regards,
>
> Laurent Pinchart
>
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Re: [PATCH v3 1/4] media: dt-bindings: media: i2c: Switch to assigned-clock-rates

[Laurent Pinchart]

Hi Prabhakar,

On Wed, Mar 18, 2020 at 08:13:00PM +0000, Lad, Prabhakar wrote:
> On Fri, Mar 13, 2020 at 9:27 PM Laurent Pinchart wrote:
> > On Fri, Mar 13, 2020 at 09:25:01PM +0000, Prabhakar Mahadev Lad wrote:
> >> On Sent: 13 March 2020 21:20, Laurent Pinchart wrote:
> >>> On Fri, Mar 13, 2020 at 09:12:31PM +0000, Lad Prabhakar wrote:
> >>>> Use assigned-clock-rates to specify the clock rate. Also mark
> >>>> clock-frequency property as deprecated.
> >>>
> >>> I would phrase it the other way around, this patch mainly deprecates clock-
> >>> frequency, and as a side effect recommends usage of assigned-clock-rates.
> >>>
> >>> "Deprecate usage of the clock-frequency propertly. The preferred method
> >>> to set clock rates is to use assigned-clock-rates."
> >>
> >> Agreed will do that.
> >>
> >>>> 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.
> >>>
> >>> I would drop this completely. Drivers need to ensure backward compatibility,
> >>> but DT bindings should only document the latest version, the history is
> >>> available in git.
> >>
> >> Sure will drop it.
> >>
> >>> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> >>>
> >>> While at it, can I enlist you to convert these bindings to yaml ? :-)
> >>>
> >> Sure will do the honours , will make sure yaml patch is ontop of this patch too.
>
> Shall I enlist you as the maintainer  in the json-schema ?
> dt_binding_check says  'maintainers' is a required property.

Do you want to be the new maintainer ? :-) Sakari is maintaining sensor
drivers (in his spare time though) so maybe he could be listed in the DT
bindings too if he wants. Otherwise, I could do it.

> > Thank you :-)
> >
> >>>>  - 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>;

-- 
Regards,

Laurent Pinchart

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Re: [PATCH v3 1/4] media: dt-bindings: media: i2c: Switch to assigned-clock-rates

[Lad, Prabhakar]

Hi Laurent,

On Wed, Mar 18, 2020 at 10:33 PM Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
> Hi Prabhakar,
>
> On Wed, Mar 18, 2020 at 08:13:00PM +0000, Lad, Prabhakar wrote:
> > On Fri, Mar 13, 2020 at 9:27 PM Laurent Pinchart wrote:
> > > On Fri, Mar 13, 2020 at 09:25:01PM +0000, Prabhakar Mahadev Lad wrote:
> > >> On Sent: 13 March 2020 21:20, Laurent Pinchart wrote:
> > >>> On Fri, Mar 13, 2020 at 09:12:31PM +0000, Lad Prabhakar wrote:
> > >>>> Use assigned-clock-rates to specify the clock rate. Also mark
> > >>>> clock-frequency property as deprecated.
> > >>>
> > >>> I would phrase it the other way around, this patch mainly deprecates clock-
> > >>> frequency, and as a side effect recommends usage of assigned-clock-rates.
> > >>>
> > >>> "Deprecate usage of the clock-frequency propertly. The preferred method
> > >>> to set clock rates is to use assigned-clock-rates."
> > >>
> > >> Agreed will do that.
> > >>
> > >>>> 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.
> > >>>
> > >>> I would drop this completely. Drivers need to ensure backward compatibility,
> > >>> but DT bindings should only document the latest version, the history is
> > >>> available in git.
> > >>
> > >> Sure will drop it.
> > >>
> > >>> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > >>>
> > >>> While at it, can I enlist you to convert these bindings to yaml ? :-)
> > >>>
> > >> Sure will do the honours , will make sure yaml patch is ontop of this patch too.
> >
> > Shall I enlist you as the maintainer  in the json-schema ?
> > dt_binding_check says  'maintainers' is a required property.
>
> Do you want to be the new maintainer ? :-) Sakari is maintaining sensor
> drivers (in his spare time though) so maybe he could be listed in the DT
> bindings too if he wants. Otherwise, I could do it.
>
OK I will add myself and Sakari for now and post a v4.

Cheers,
--Prabhakar

> > > Thank you :-)
> > >
> > >>>>  - 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>;
>
> --
> Regards,
>
> Laurent Pinchart

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Re: [PATCH v3 3/4] media: i2c: ov5645: Set maximum leverage of external clock frequency to 24480000

[Lad, Prabhakar]

Hi Laurent,

On Fri, Mar 13, 2020 at 9:31 PM Prabhakar Mahadev Lad
<prabhakar.mahadev-lad.rj@bp.renesas.com> wrote:
>
> Hi Laurent,
>
> Thank you for the review.
>
> > -----Original Message-----
> > From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > Sent: 13 March 2020 21:24
> > 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>; Geert Uytterhoeven <geert@linux-m68k.org>;
> > devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; linux-renesas-
> > soc@vger.kernel.org; Fabio Estevam <festevam@gmail.com>; linux-
> > media@vger.kernel.org; linux-arm-kernel@lists.infradead.org
> > Subject: Re: [PATCH v3 3/4] media: i2c: ov5645: Set maximum leverage of
> > external clock frequency to 24480000
> >
> > Hi Prabhakar,
> >
> > Thank you for the patch.
> >
> > On Fri, Mar 13, 2020 at 09:12:33PM +0000, Lad Prabhakar wrote:
> > > While testing on Renesas RZ/G2E platform, noticed the clock frequency
> > > to be 24242424 as a result the probe failed. However increasing the
> > > maximum leverage of external clock frequency to 24480000 fixes this
> > > issue. Since this difference is small enough and is insignificant set
> > > the same in the driver.
> > >
> > > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-
> > lad.rj@bp.renesas.com>
> > > ---
> > >  drivers/media/i2c/ov5645.c | 6 ++++--
> > >  1 file changed, 4 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/media/i2c/ov5645.c b/drivers/media/i2c/ov5645.c
> > > index 4fbabf3..b49359b 100644
> > > --- a/drivers/media/i2c/ov5645.c
> > > +++ b/drivers/media/i2c/ov5645.c
> > > @@ -1107,8 +1107,10 @@ static int ov5645_probe(struct i2c_client *client)
> > >  }
> > >
> > >  xclk_freq = clk_get_rate(ov5645->xclk);
> > > -/* external clock must be 24MHz, allow 1% tolerance */
> > > -if (xclk_freq < 23760000 || xclk_freq > 24240000) {
> > > +/* external clock must be 24MHz, allow a minimum 1% and a
> > maximum of 2%
> > > + * tolerance
> >
> > So where do these numbers come from ? I understand that 2% is what you
> > need to make your clock fit in the range, but why -1%/+2% instead of -
> > 2%/+2% ? And why not 2.5 or 3% ? The sensor datasheet documents the
> > range of supported xvclk frequencies to be 6MHz to 54MHz. I understand
> > that PLL parameters depend on the clock frequency, but could they be
> > calculated instead of hardcoded, to avoid requiring an exact 24MHz input
> > frequency ?
> >
> To be honest I don't have the datasheet for ov5645, the flyer says 6-54Mhz but the
> logs/comment says 24Mhz.
>
Comparing to ov5640 datasheet [1] (which I am assuming might be
similar to ov5645), this change should affect the driver.

[1] https://cdn.sparkfun.com/datasheets/Sensors/LightImaging/OV5640_datasheet.pdf

Cheers,
--Prabhakar

> Cheers,
> --Prabhakar
>
> > > + */
> > > +if (xclk_freq < 23760000 || xclk_freq > 24480000) {
> > >  dev_err(dev, "external clock frequency %u is not
> > supported\n",
> > >  xclk_freq);
> > >  return -EINVAL;
> >
> > --
> > Regards,
> >
> > Laurent Pinchart
>
>
> Renesas Electronics Europe GmbH, Geschaeftsfuehrer/President: Carsten Jauch, Sitz der Gesellschaft/Registered office: Duesseldorf, Arcadiastrasse 10, 40472 Duesseldorf, Germany, Handelsregister/Commercial Register: Duesseldorf, HRB 3708 USt-IDNr./Tax identification no.: DE 119353406 WEEE-Reg.-Nr./WEEE reg. no.: DE 14978647
> _______________________________________________
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> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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Re: [PATCH v3 3/4] media: i2c: ov5645: Set maximum leverage of external clock frequency to 24480000

[Laurent Pinchart]

Hi Prabhakar,

On Fri, Mar 13, 2020 at 09:31:25PM +0000, Prabhakar Mahadev Lad wrote:
> On 13 March 2020 21:24, Laurent Pinchart wrote:
> > On Fri, Mar 13, 2020 at 09:12:33PM +0000, Lad Prabhakar wrote:
> > > While testing on Renesas RZ/G2E platform, noticed the clock frequency
> > > to be 24242424 as a result the probe failed. However increasing the
> > > maximum leverage of external clock frequency to 24480000 fixes this
> > > issue. Since this difference is small enough and is insignificant set
> > > the same in the driver.
> > >
> > > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> > > ---
> > >  drivers/media/i2c/ov5645.c | 6 ++++--
> > >  1 file changed, 4 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/media/i2c/ov5645.c b/drivers/media/i2c/ov5645.c
> > > index 4fbabf3..b49359b 100644
> > > --- a/drivers/media/i2c/ov5645.c
> > > +++ b/drivers/media/i2c/ov5645.c
> > > @@ -1107,8 +1107,10 @@ static int ov5645_probe(struct i2c_client *client)
> > >  }
> > >
> > >  xclk_freq = clk_get_rate(ov5645->xclk);
> > > -/* external clock must be 24MHz, allow 1% tolerance */
> > > -if (xclk_freq < 23760000 || xclk_freq > 24240000) {
> > > +/* external clock must be 24MHz, allow a minimum 1% and a maximum of 2%
> > > + * tolerance
> >
> > So where do these numbers come from ? I understand that 2% is what you
> > need to make your clock fit in the range, but why -1%/+2% instead of -
> > 2%/+2% ? And why not 2.5 or 3% ? The sensor datasheet documents the
> > range of supported xvclk frequencies to be 6MHz to 54MHz. I understand
> > that PLL parameters depend on the clock frequency, but could they be
> > calculated instead of hardcoded, to avoid requiring an exact 24MHz input
> > frequency ?
>
> To be honest I don't have the datasheet for ov5645, the flyer says 6-54Mhz but the
> logs/comment says 24Mhz.

The OV5645 clock topology is fairly complex, with two PLLs and different
set of output dividers. It however shouldn't be impossible to calculate
the PLL configuration in the driver, but would require some dedication,
and is probably not worth it.

I've discussed the matter with Sakari, and we concluded that this is
just a sanity check. We advise increasing the tolerance by a bigger
amount to avoid patching this for every new board (completely
arbitrarily, +/- 5%), and turning the fatal error into a dev_warn,
dropping the return -EINVAL statement.

> > > + */
> > > +if (xclk_freq < 23760000 || xclk_freq > 24480000) {
> > >  dev_err(dev, "external clock frequency %u is not supported\n",
> > >  xclk_freq);
> > >  return -EINVAL;

-- 
Regards,

Laurent Pinchart

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Re: [PATCH v3 3/4] media: i2c: ov5645: Set maximum leverage of external clock frequency to 24480000

[Laurent Pinchart]

Hi Prabhakar,

On Wed, Mar 18, 2020 at 10:41:57PM +0000, Lad, Prabhakar wrote:
> On Fri, Mar 13, 2020 at 9:31 PM Prabhakar Mahadev Lad wrote:
> > On 13 March 2020 21:24, Laurent Pinchart wrote:
> >> On Fri, Mar 13, 2020 at 09:12:33PM +0000, Lad Prabhakar wrote:
> >>> While testing on Renesas RZ/G2E platform, noticed the clock frequency
> >>> to be 24242424 as a result the probe failed. However increasing the
> >>> maximum leverage of external clock frequency to 24480000 fixes this
> >>> issue. Since this difference is small enough and is insignificant set
> >>> the same in the driver.
> >>>
> >>> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> >>> ---
> >>>  drivers/media/i2c/ov5645.c | 6 ++++--
> >>>  1 file changed, 4 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/drivers/media/i2c/ov5645.c b/drivers/media/i2c/ov5645.c
> >>> index 4fbabf3..b49359b 100644
> >>> --- a/drivers/media/i2c/ov5645.c
> >>> +++ b/drivers/media/i2c/ov5645.c
> >>> @@ -1107,8 +1107,10 @@ static int ov5645_probe(struct i2c_client *client)
> >>>  }
> >>>
> >>>  xclk_freq = clk_get_rate(ov5645->xclk);
> >>> -/* external clock must be 24MHz, allow 1% tolerance */
> >>> -if (xclk_freq < 23760000 || xclk_freq > 24240000) {
> >>> +/* external clock must be 24MHz, allow a minimum 1% and a
> >> maximum of 2%
> >>> + * tolerance
> >>
> >> So where do these numbers come from ? I understand that 2% is what you
> >> need to make your clock fit in the range, but why -1%/+2% instead of -
> >> 2%/+2% ? And why not 2.5 or 3% ? The sensor datasheet documents the
> >> range of supported xvclk frequencies to be 6MHz to 54MHz. I understand
> >> that PLL parameters depend on the clock frequency, but could they be
> >> calculated instead of hardcoded, to avoid requiring an exact 24MHz input
> >> frequency ?
> >>
> > To be honest I don't have the datasheet for ov5645, the flyer says 6-54Mhz but the
> > logs/comment says 24Mhz.
> >
> Comparing to ov5640 datasheet [1] (which I am assuming might be
> similar to ov5645),

Let's assume this to be the case, I see no reason not to :-)

> this change should affect the driver.

How do you mean ?

> [1] https://cdn.sparkfun.com/datasheets/Sensors/LightImaging/OV5640_datasheet.pdf
> 
> >>> + */
> >>> +if (xclk_freq < 23760000 || xclk_freq > 24480000) {
> >>>  dev_err(dev, "external clock frequency %u is not supported\n",
> >>>  xclk_freq);
> >>>  return -EINVAL;

-- 
Regards,

Laurent Pinchart

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Re: [PATCH v3 3/4] media: i2c: ov5645: Set maximum leverage of external clock frequency to 24480000

[Lad, Prabhakar]

Hi Laurent,

On Wed, Mar 18, 2020 at 11:19 PM Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
> Hi Prabhakar,
>
> On Fri, Mar 13, 2020 at 09:31:25PM +0000, Prabhakar Mahadev Lad wrote:
> > On 13 March 2020 21:24, Laurent Pinchart wrote:
> > > On Fri, Mar 13, 2020 at 09:12:33PM +0000, Lad Prabhakar wrote:
> > > > While testing on Renesas RZ/G2E platform, noticed the clock frequency
> > > > to be 24242424 as a result the probe failed. However increasing the
> > > > maximum leverage of external clock frequency to 24480000 fixes this
> > > > issue. Since this difference is small enough and is insignificant set
> > > > the same in the driver.
> > > >
> > > > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> > > > ---
> > > >  drivers/media/i2c/ov5645.c | 6 ++++--
> > > >  1 file changed, 4 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/drivers/media/i2c/ov5645.c b/drivers/media/i2c/ov5645.c
> > > > index 4fbabf3..b49359b 100644
> > > > --- a/drivers/media/i2c/ov5645.c
> > > > +++ b/drivers/media/i2c/ov5645.c
> > > > @@ -1107,8 +1107,10 @@ static int ov5645_probe(struct i2c_client *client)
> > > >  }
> > > >
> > > >  xclk_freq = clk_get_rate(ov5645->xclk);
> > > > -/* external clock must be 24MHz, allow 1% tolerance */
> > > > -if (xclk_freq < 23760000 || xclk_freq > 24240000) {
> > > > +/* external clock must be 24MHz, allow a minimum 1% and a maximum of 2%
> > > > + * tolerance
> > >
> > > So where do these numbers come from ? I understand that 2% is what you
> > > need to make your clock fit in the range, but why -1%/+2% instead of -
> > > 2%/+2% ? And why not 2.5 or 3% ? The sensor datasheet documents the
> > > range of supported xvclk frequencies to be 6MHz to 54MHz. I understand
> > > that PLL parameters depend on the clock frequency, but could they be
> > > calculated instead of hardcoded, to avoid requiring an exact 24MHz input
> > > frequency ?
> >
> > To be honest I don't have the datasheet for ov5645, the flyer says 6-54Mhz but the
> > logs/comment says 24Mhz.
>
> The OV5645 clock topology is fairly complex, with two PLLs and different
> set of output dividers. It however shouldn't be impossible to calculate
> the PLL configuration in the driver, but would require some dedication,
> and is probably not worth it.
>
> I've discussed the matter with Sakari, and we concluded that this is
> just a sanity check. We advise increasing the tolerance by a bigger
> amount to avoid patching this for every new board (completely
> arbitrarily, +/- 5%), and turning the fatal error into a dev_warn,
> dropping the return -EINVAL statement.
>
Thank you for looking into this. I'll update the patch accordingly.

Cheers,
--Prabhakar

> > > > + */
> > > > +if (xclk_freq < 23760000 || xclk_freq > 24480000) {
> > > >  dev_err(dev, "external clock frequency %u is not supported\n",
> > > >  xclk_freq);
> > > >  return -EINVAL;
>
> --
> Regards,
>
> Laurent Pinchart
>
> _______________________________________________
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> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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Re: [PATCH v3 3/4] media: i2c: ov5645: Set maximum leverage of external clock frequency to 24480000

[Lad, Prabhakar]

Hi Laurent,

On Wed, Mar 18, 2020 at 11:22 PM Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
> Hi Prabhakar,
>
> On Wed, Mar 18, 2020 at 10:41:57PM +0000, Lad, Prabhakar wrote:
> > On Fri, Mar 13, 2020 at 9:31 PM Prabhakar Mahadev Lad wrote:
> > > On 13 March 2020 21:24, Laurent Pinchart wrote:
> > >> On Fri, Mar 13, 2020 at 09:12:33PM +0000, Lad Prabhakar wrote:
> > >>> While testing on Renesas RZ/G2E platform, noticed the clock frequency
> > >>> to be 24242424 as a result the probe failed. However increasing the
> > >>> maximum leverage of external clock frequency to 24480000 fixes this
> > >>> issue. Since this difference is small enough and is insignificant set
> > >>> the same in the driver.
> > >>>
> > >>> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> > >>> ---
> > >>>  drivers/media/i2c/ov5645.c | 6 ++++--
> > >>>  1 file changed, 4 insertions(+), 2 deletions(-)
> > >>>
> > >>> diff --git a/drivers/media/i2c/ov5645.c b/drivers/media/i2c/ov5645.c
> > >>> index 4fbabf3..b49359b 100644
> > >>> --- a/drivers/media/i2c/ov5645.c
> > >>> +++ b/drivers/media/i2c/ov5645.c
> > >>> @@ -1107,8 +1107,10 @@ static int ov5645_probe(struct i2c_client *client)
> > >>>  }
> > >>>
> > >>>  xclk_freq = clk_get_rate(ov5645->xclk);
> > >>> -/* external clock must be 24MHz, allow 1% tolerance */
> > >>> -if (xclk_freq < 23760000 || xclk_freq > 24240000) {
> > >>> +/* external clock must be 24MHz, allow a minimum 1% and a
> > >> maximum of 2%
> > >>> + * tolerance
> > >>
> > >> So where do these numbers come from ? I understand that 2% is what you
> > >> need to make your clock fit in the range, but why -1%/+2% instead of -
> > >> 2%/+2% ? And why not 2.5 or 3% ? The sensor datasheet documents the
> > >> range of supported xvclk frequencies to be 6MHz to 54MHz. I understand
> > >> that PLL parameters depend on the clock frequency, but could they be
> > >> calculated instead of hardcoded, to avoid requiring an exact 24MHz input
> > >> frequency ?
> > >>
> > > To be honest I don't have the datasheet for ov5645, the flyer says 6-54Mhz but the
> > > logs/comment says 24Mhz.
> > >
> > Comparing to ov5640 datasheet [1] (which I am assuming might be
> > similar to ov5645),
>
> Let's assume this to be the case, I see no reason not to :-)
>
> > this change should affect the driver.
>
> How do you mean ?
>
Oops sorry for for the typo I meant shouldn't affect the driver :)

Cheers,
--Prabhakar

> > [1] https://cdn.sparkfun.com/datasheets/Sensors/LightImaging/OV5640_datasheet.pdf
> >
> > >>> + */
> > >>> +if (xclk_freq < 23760000 || xclk_freq > 24480000) {
> > >>>  dev_err(dev, "external clock frequency %u is not supported\n",
> > >>>  xclk_freq);
> > >>>  return -EINVAL;
>
> --
> Regards,
>
> Laurent Pinchart

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Re: [PATCH v3 1/4] media: dt-bindings: media: i2c: Switch to assigned-clock-rates

[Maxime Ripard]

[-- Attachment #1.1: Type: text/plain, Size: 1913 bytes --]

Hi,

On Fri, Mar 13, 2020 at 09:12:31PM +0000, Lad Prabhakar wrote:
> 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>;

clock-frequency is quite different from assigned-clock-rates though,
semantically speaking. clock-frequency is only about what the clock
frequency is, while assigned-clock-rates will change the rate as well,
and you have no idea how long it will last.

If you want to retrieve that through the clock framework, then just
making clock-frequency optional is enough and falling back to
clk_get_rate on the clocks property already provided is enough.

Maxime

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Re: [PATCH v3 1/4] media: dt-bindings: media: i2c: Switch to assigned-clock-rates

[Laurent Pinchart]

Hi Maxime,

On Thu, Mar 19, 2020 at 01:44:52PM +0100, Maxime Ripard wrote:
> On Fri, Mar 13, 2020 at 09:12:31PM +0000, Lad Prabhakar wrote:
> > 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>;
> 
> clock-frequency is quite different from assigned-clock-rates though,
> semantically speaking. clock-frequency is only about what the clock
> frequency is, while assigned-clock-rates will change the rate as well,
> and you have no idea how long it will last.

The driver currently reads the clock-frequency property and then calls
clk_set_rate(). I agree tht assigned-clock-rates isn't a panacea, but I
think it's less of a hack than what we currently have.

As discussed on IRC, maybe the best option in this specific case is to
drop clock-frequency and assigned-clok-rates, and call clk_set_rate()
with a hardcoded frequency of 24MHz in the driver, as that's the only
frequency the driver supports.

> If you want to retrieve that through the clock framework, then just
> making clock-frequency optional is enough and falling back to
> clk_get_rate on the clocks property already provided is enough.

-- 
Regards,

Laurent Pinchart

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Re: [PATCH v3 1/4] media: dt-bindings: media: i2c: Switch to assigned-clock-rates

[Lad, Prabhakar]

Hi Maxime,

Thank you for the review.

On Thu, Mar 19, 2020 at 12:45 PM Maxime Ripard <maxime@cerno.tech> wrote:
>
> Hi,
>
> On Fri, Mar 13, 2020 at 09:12:31PM +0000, Lad Prabhakar wrote:
> > 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>;
>
> clock-frequency is quite different from assigned-clock-rates though,
> semantically speaking. clock-frequency is only about what the clock
> frequency is, while assigned-clock-rates will change the rate as well,
> and you have no idea how long it will last.
>
Agreed clock-frequency tells whats the clock frequency, wrt ov5645 driver
this property was read and and the clock rate was changed accordingly as per
the value being passed. So switching  to assigned-clock-rates does bypass
of clock rate being set in the ov5645 driver [1] as the framework does it.

> If you want to retrieve that through the clock framework, then just
> making clock-frequency optional is enough and falling back to
> clk_get_rate on the clocks property already provided is enough.
>
As done in patch [1] ?

Fyi I have posted a v4 [2] to ML.

[1] https://patchwork.linuxtv.org/patch/62378/
[2] https://patchwork.linuxtv.org/project/linux-media/list/?series=1990

Cheers,
--Prabhakar

> Maxime
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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Re: [PATCH v3 1/4] media: dt-bindings: media: i2c: Switch to assigned-clock-rates

[Lad, Prabhakar]

Hi Laurent,

On Thu, Mar 19, 2020 at 1:04 PM Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
> Hi Maxime,
>
> On Thu, Mar 19, 2020 at 01:44:52PM +0100, Maxime Ripard wrote:
> > On Fri, Mar 13, 2020 at 09:12:31PM +0000, Lad Prabhakar wrote:
> > > 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>;
> >
> > clock-frequency is quite different from assigned-clock-rates though,
> > semantically speaking. clock-frequency is only about what the clock
> > frequency is, while assigned-clock-rates will change the rate as well,
> > and you have no idea how long it will last.
>
> The driver currently reads the clock-frequency property and then calls
> clk_set_rate(). I agree tht assigned-clock-rates isn't a panacea, but I
> think it's less of a hack than what we currently have.
>
> As discussed on IRC, maybe the best option in this specific case is to
> drop clock-frequency and assigned-clok-rates, and call clk_set_rate()
> with a hardcoded frequency of 24MHz in the driver, as that's the only
> frequency the driver supports.
>
Does this mean any driver which has a fixed clock requirement shouldn't be a
DT property and should be just handled by the drivers internally ?

Cheers,
--Prabhakar

> > If you want to retrieve that through the clock framework, then just
> > making clock-frequency optional is enough and falling back to
> > clk_get_rate on the clocks property already provided is enough.
>
> --
> Regards,
>
> Laurent Pinchart
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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Re: [PATCH v3 1/4] media: dt-bindings: media: i2c: Switch to assigned-clock-rates

[Maxime Ripard]

[-- Attachment #1.1: Type: text/plain, Size: 3288 bytes --]

On Thu, Mar 19, 2020 at 01:17:51PM +0000, Lad, Prabhakar wrote:
> Hi Laurent,
>
> On Thu, Mar 19, 2020 at 1:04 PM Laurent Pinchart
> <laurent.pinchart@ideasonboard.com> wrote:
> >
> > Hi Maxime,
> >
> > On Thu, Mar 19, 2020 at 01:44:52PM +0100, Maxime Ripard wrote:
> > > On Fri, Mar 13, 2020 at 09:12:31PM +0000, Lad Prabhakar wrote:
> > > > 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>;
> > >
> > > clock-frequency is quite different from assigned-clock-rates though,
> > > semantically speaking. clock-frequency is only about what the clock
> > > frequency is, while assigned-clock-rates will change the rate as well,
> > > and you have no idea how long it will last.
> >
> > The driver currently reads the clock-frequency property and then calls
> > clk_set_rate(). I agree tht assigned-clock-rates isn't a panacea, but I
> > think it's less of a hack than what we currently have.
> >
> > As discussed on IRC, maybe the best option in this specific case is to
> > drop clock-frequency and assigned-clok-rates, and call clk_set_rate()
> > with a hardcoded frequency of 24MHz in the driver, as that's the only
> > frequency the driver supports.
> >
> Does this mean any driver which has a fixed clock requirement shouldn't be a
> DT property and should be just handled by the drivers internally ?

It's hard to give a generic policy, but here, the hardware is pretty
flexible since it can deal with anything between 6MHz to 50-something
MHz, it's the driver that chooses to enforce a 24MHz and be pedantic
about it, so it's up to the driver to enforce that policy, not to the
DT since it's essentially a software limitation, not a hardware one.

Maxime

[-- Attachment #1.2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]

[-- Attachment #2: Type: text/plain, Size: 176 bytes --]

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Re: [PATCH v3 1/4] media: dt-bindings: media: i2c: Switch to assigned-clock-rates

[Lad, Prabhakar]

Hi Maxime,

On Tue, Mar 24, 2020 at 3:40 PM Maxime Ripard <maxime@cerno.tech> wrote:
>
> On Thu, Mar 19, 2020 at 01:17:51PM +0000, Lad, Prabhakar wrote:
> > Hi Laurent,
> >
> > On Thu, Mar 19, 2020 at 1:04 PM Laurent Pinchart
> > <laurent.pinchart@ideasonboard.com> wrote:
> > >
> > > Hi Maxime,
> > >
> > > On Thu, Mar 19, 2020 at 01:44:52PM +0100, Maxime Ripard wrote:
> > > > On Fri, Mar 13, 2020 at 09:12:31PM +0000, Lad Prabhakar wrote:
> > > > > 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>;
> > > >
> > > > clock-frequency is quite different from assigned-clock-rates though,
> > > > semantically speaking. clock-frequency is only about what the clock
> > > > frequency is, while assigned-clock-rates will change the rate as well,
> > > > and you have no idea how long it will last.
> > >
> > > The driver currently reads the clock-frequency property and then calls
> > > clk_set_rate(). I agree tht assigned-clock-rates isn't a panacea, but I
> > > think it's less of a hack than what we currently have.
> > >
> > > As discussed on IRC, maybe the best option in this specific case is to
> > > drop clock-frequency and assigned-clok-rates, and call clk_set_rate()
> > > with a hardcoded frequency of 24MHz in the driver, as that's the only
> > > frequency the driver supports.
> > >
> > Does this mean any driver which has a fixed clock requirement shouldn't be a
> > DT property and should be just handled by the drivers internally ?
>
> It's hard to give a generic policy, but here, the hardware is pretty
> flexible since it can deal with anything between 6MHz to 50-something
> MHz, it's the driver that chooses to enforce a 24MHz and be pedantic
> about it, so it's up to the driver to enforce that policy, not to the
> DT since it's essentially a software limitation, not a hardware one.
>
Thank you for the clarification, Ill drop patches 1-4 from this series.

Cheers,
--Prabhakar

> Maxime
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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Re: [PATCH v3 1/4] media: dt-bindings: media: i2c: Switch to assigned-clock-rates

[Laurent Pinchart]

Hi Prabhakar,

On Tue, Mar 24, 2020 at 04:04:43PM +0000, Lad, Prabhakar wrote:
> On Tue, Mar 24, 2020 at 3:40 PM Maxime Ripard <maxime@cerno.tech> wrote:
> > On Thu, Mar 19, 2020 at 01:17:51PM +0000, Lad, Prabhakar wrote:
> > > On Thu, Mar 19, 2020 at 1:04 PM Laurent Pinchart wrote:
> > > > On Thu, Mar 19, 2020 at 01:44:52PM +0100, Maxime Ripard wrote:
> > > > > On Fri, Mar 13, 2020 at 09:12:31PM +0000, Lad Prabhakar wrote:
> > > > > > 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>;
> > > > >
> > > > > clock-frequency is quite different from assigned-clock-rates though,
> > > > > semantically speaking. clock-frequency is only about what the clock
> > > > > frequency is, while assigned-clock-rates will change the rate as well,
> > > > > and you have no idea how long it will last.
> > > >
> > > > The driver currently reads the clock-frequency property and then calls
> > > > clk_set_rate(). I agree tht assigned-clock-rates isn't a panacea, but I
> > > > think it's less of a hack than what we currently have.
> > > >
> > > > As discussed on IRC, maybe the best option in this specific case is to
> > > > drop clock-frequency and assigned-clok-rates, and call clk_set_rate()
> > > > with a hardcoded frequency of 24MHz in the driver, as that's the only
> > > > frequency the driver supports.
> > > >
> > > Does this mean any driver which has a fixed clock requirement shouldn't be a
> > > DT property and should be just handled by the drivers internally ?
> >
> > It's hard to give a generic policy, but here, the hardware is pretty
> > flexible since it can deal with anything between 6MHz to 50-something
> > MHz, it's the driver that chooses to enforce a 24MHz and be pedantic
> > about it, so it's up to the driver to enforce that policy, not to the
> > DT since it's essentially a software limitation, not a hardware one.
>
> Thank you for the clarification, Ill drop patches 1-4 from this series.

That's the whole series... :-) I think you should keep patch 1/4 but
just remove the clock-frequency from the bindings, then remove it from
the DT files, and patch the driver to set the clock rate to 24MHz
unconditionally in patch 4/4.

-- 
Regards,

Laurent Pinchart

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Re: [PATCH v3 1/4] media: dt-bindings: media: i2c: Switch to assigned-clock-rates

[Lad, Prabhakar]

Hi Laurent,

On Tue, Mar 24, 2020 at 4:12 PM Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
> Hi Prabhakar,
>
> On Tue, Mar 24, 2020 at 04:04:43PM +0000, Lad, Prabhakar wrote:
> > On Tue, Mar 24, 2020 at 3:40 PM Maxime Ripard <maxime@cerno.tech> wrote:
> > > On Thu, Mar 19, 2020 at 01:17:51PM +0000, Lad, Prabhakar wrote:
> > > > On Thu, Mar 19, 2020 at 1:04 PM Laurent Pinchart wrote:
> > > > > On Thu, Mar 19, 2020 at 01:44:52PM +0100, Maxime Ripard wrote:
> > > > > > On Fri, Mar 13, 2020 at 09:12:31PM +0000, Lad Prabhakar wrote:
> > > > > > > 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>;
> > > > > >
> > > > > > clock-frequency is quite different from assigned-clock-rates though,
> > > > > > semantically speaking. clock-frequency is only about what the clock
> > > > > > frequency is, while assigned-clock-rates will change the rate as well,
> > > > > > and you have no idea how long it will last.
> > > > >
> > > > > The driver currently reads the clock-frequency property and then calls
> > > > > clk_set_rate(). I agree tht assigned-clock-rates isn't a panacea, but I
> > > > > think it's less of a hack than what we currently have.
> > > > >
> > > > > As discussed on IRC, maybe the best option in this specific case is to
> > > > > drop clock-frequency and assigned-clok-rates, and call clk_set_rate()
> > > > > with a hardcoded frequency of 24MHz in the driver, as that's the only
> > > > > frequency the driver supports.
> > > > >
> > > > Does this mean any driver which has a fixed clock requirement shouldn't be a
> > > > DT property and should be just handled by the drivers internally ?
> > >
> > > It's hard to give a generic policy, but here, the hardware is pretty
> > > flexible since it can deal with anything between 6MHz to 50-something
> > > MHz, it's the driver that chooses to enforce a 24MHz and be pedantic
> > > about it, so it's up to the driver to enforce that policy, not to the
> > > DT since it's essentially a software limitation, not a hardware one.
> >
> > Thank you for the clarification, Ill drop patches 1-4 from this series.
>
> That's the whole series... :-) I think you should keep patch 1/4 but
> just remove the clock-frequency from the bindings, then remove it from
> the DT files, and patch the driver to set the clock rate to 24MHz
> unconditionally in patch 4/4.
>
My bad I was referring to v4 series patch 5/5 which converts dt
bindings to json schema.
I'll shall post a v5 as suggested above.

Cheers,
--Prabhakar

> --
> Regards,
>
> Laurent Pinchart

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