linux-kernel - Re: [PATCH v7 3/3] media: ov8856: Implement sensor module revision identification

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Date:   Tue, 5 May 2020 12:17:29 +0200
From:   Marco Felsch <m.felsch@...gutronix.de>
To:     Robert Foss <robert.foss@...aro.org>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Sakari Ailus <sakari.ailus@....fi>,
        Maxime Ripard <maxime@...no.tech>, linux-media@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Dongchun Zhu <dongchun.zhu@...iatek.com>,
        Fabio Estevam <festevam@...il.com>,
        Tomasz Figa <tfiga@...omium.org>, Ben Kao <ben.kao@...el.com>
Subject: Re: [PATCH v7 3/3] media: ov8856: Implement sensor module revision
 identification

Hi Robert,

On 20-05-05 12:01, Robert Foss wrote:
> Query the sensor for its module revision, and compare it
> to known revisions.
> 
> Currently 2A and 1B revision indentification is supported.
> 
> Signed-off-by: Robert Foss <robert.foss@...aro.org>
> ---
> 
> - Changes since v3:
>   * Actually add module revision 2A
> 
> - Changes since v2:
>   * Add module revision 2A
>   * Sakari: Remove ov8856_check_revision()
>   * Sakari: Stop EEPROM streaming mode
> 
>  drivers/media/i2c/ov8856.c | 53 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 53 insertions(+)
> 
> diff --git a/drivers/media/i2c/ov8856.c b/drivers/media/i2c/ov8856.c
> index e6418a79801e..3c82c3e588d7 100644
> --- a/drivers/media/i2c/ov8856.c
> +++ b/drivers/media/i2c/ov8856.c
> @@ -32,6 +32,19 @@
>  #define OV8856_MODE_STANDBY		0x00
>  #define OV8856_MODE_STREAMING		0x01
>  
> +/* module revisions */
> +#define OV8856_2A_MODULE		0x01
> +#define OV8856_1B_MODULE		0x02
> +
> +/* the OTP read-out buffer is at 0x7000 and 0xf is the offset
> + * of the byte in the OTP that means the module revision
> + */
> +#define OV8856_MODULE_REVISION		0x700f
> +#define OV8856_OTP_MODE_CTRL		0x3d84
> +#define OV8856_OTP_LOAD_CTRL		0x3d81
> +#define OV8856_OTP_MODE_AUTO		0x00
> +#define OV8856_OTP_LOAD_CTRL_ENABLE	BIT(0)
> +
>  /* vertical-timings from sensor */
>  #define OV8856_REG_VTS			0x380e
>  #define OV8856_VTS_MAX			0x7fff
> @@ -1152,6 +1165,46 @@ static int ov8856_identify_module(struct ov8856 *ov8856)
>  		return -ENXIO;
>  	}
>  
> +	ret = ov8856_write_reg(ov8856, OV8856_REG_MODE_SELECT,
> +			       OV8856_REG_VALUE_08BIT, OV8856_MODE_STREAMING);
> +	if (ret)
> +		return ret;
> +
> +	ret = ov8856_write_reg(ov8856, OV8856_OTP_MODE_CTRL,
> +			       OV8856_REG_VALUE_08BIT, OV8856_OTP_MODE_AUTO);
> +	if (ret) {
> +		dev_err(&client->dev, "failed to set otp mode");
> +		return ret;
> +	}
> +
> +	ret = ov8856_write_reg(ov8856, OV8856_OTP_LOAD_CTRL,
> +			       OV8856_REG_VALUE_08BIT,
> +			       OV8856_OTP_LOAD_CTRL_ENABLE);
> +	if (ret) {
> +		dev_err(&client->dev, "failed to enable load control");
> +		return ret;
> +	}
> +
> +	ret = ov8856_read_reg(ov8856, OV8856_MODULE_REVISION,
> +			      OV8856_REG_VALUE_08BIT, &val);
> +	if (ret) {
> +		dev_err(&client->dev, "failed to read module revision");
> +		return ret;
> +	}
> +
> +	dev_info(&client->dev, "OV8856 revision %x (%s) at address 0x%02x\n",
> +		val,
> +		val == OV8856_2A_MODULE ? "2A" :
> +		val == OV8856_1B_MODULE ? "1B" : "unknown revision",
> +		client->addr);

Pls check the alignment here too.

Regards,
  Marco

> +
> +	ret = ov8856_write_reg(ov8856, OV8856_REG_MODE_SELECT,
> +			       OV8856_REG_VALUE_08BIT, OV8856_MODE_STANDBY);
> +	if (ret) {
> +		dev_err(&client->dev, "failed to exit streaming mode");
> +		return ret;
> +	}
> +
>  	return 0;
>  }
>  
> -- 
> 2.25.1