Re: [RFC PATCH] media: i2c: mt9p031: Add 8-bit support

Laurent Pinchart
2017-07-18T14:34:07Z

Hi Adam,

Thank you for the patch.

On Tuesday 18 Jul 2017 09:00:54 Adam Ford wrote:
> From: Adam Ford <adam.ford@logicpd.com>
>
> By default the camera driver only supports monochrome or color at 12-bit.
> This patch will allow the camera to choose between 12-bit or 8-bit
> resolution. Tested on Logic PD DM3730 Torpedo Development Kit.

I don't think that's right. The MT9P031 can't output 8-bit data. What can be
done, of course, is connect only the topmost 8 bits of the 12-bit output to an
8-bit input on a receiver. That supported through the data-shift property that
should be set on the receiver DT endpoint node.

> Signed-off-by: Adam Ford <adam.ford@logicpd.com>
>
> diff --git a/Documentation/devicetree/bindings/media/i2c/mt9p031.txt
> b/Documentation/devicetree/bindings/media/i2c/mt9p031.txt index
> cb60443..77b0dc1 100644
> --- a/Documentation/devicetree/bindings/media/i2c/mt9p031.txt
> +++ b/Documentation/devicetree/bindings/media/i2c/mt9p031.txt
> @@ -15,6 +15,7 @@ Required Properties:
>
> Optional Properties:
> - reset-gpios: Chip reset GPIO
> +- resolution: Empty (12-bit) or 8 bit resolution
>
> For further reading on port node refer to
> Documentation/devicetree/bindings/media/video-interfaces.txt.
> diff --git a/drivers/media/i2c/mt9p031.c b/drivers/media/i2c/mt9p031.c
> index 91d822f..355791d 100644
> --- a/drivers/media/i2c/mt9p031.c
> +++ b/drivers/media/i2c/mt9p031.c
> @@ -1024,6 +1024,7 @@ mt9p031_get_pdata(struct i2c_client *client)
>
> of_property_read_u32(np, "input-clock-frequency", &pdata->ext_freq);
> of_property_read_u32(np, "pixel-clock-frequency", &pdata-
>target_freq);
> + of_property_read_u32(np, "resolution", &pdata->resolution);
>
> done:
> of_node_put(np);
> @@ -1058,6 +1059,7 @@ static int mt9p031_probe(struct i2c_client *client,
> mt9p031->output_control = MT9P031_OUTPUT_CONTROL_DEF;
> mt9p031->mode2 = MT9P031_READ_MODE_2_ROW_BLC;
> mt9p031->model = did->driver_data;
> + mt9p031->resolution = pdata->resolution;
>
> mt9p031->regulators[0].supply = "vdd";
> mt9p031->regulators[1].supply = "vdd_io";
> @@ -1123,11 +1125,18 @@ static int mt9p031_probe(struct i2c_client *client,
> mt9p031->crop.left = MT9P031_COLUMN_START_DEF;
> mt9p031->crop.top = MT9P031_ROW_START_DEF;
>
> - if (mt9p031->model == MT9P031_MODEL_MONOCHROME)
> - mt9p031->format.code = MEDIA_BUS_FMT_Y12_1X12;
> - else
> - mt9p031->format.code = MEDIA_BUS_FMT_SGRBG12_1X12;
> -
> + if (mt9p031->model == MT9P031_MODEL_MONOCHROME) {
> + if (mt9p031->resolution == 8)
> + mt9p031->format.code = MEDIA_BUS_FMT_Y8_1X8;
> + else
> + mt9p031->format.code = MEDIA_BUS_FMT_Y12_1X12;
> + }
> + else {
> + if (mt9p031->resolution == 8)
> + mt9p031->format.code = MEDIA_BUS_FMT_SGRBG8_1X8;
> + else
> + mt9p031->format.code = MEDIA_BUS_FMT_SGRBG12_1X12;
> + }
> mt9p031->format.width = MT9P031_WINDOW_WIDTH_DEF;
> mt9p031->format.height = MT9P031_WINDOW_HEIGHT_DEF;
> mt9p031->format.field = V4L2_FIELD_NONE;
> diff --git a/include/media/i2c/mt9p031.h b/include/media/i2c/mt9p031.h
> index 1ba3612..84335cb 100644
> --- a/include/media/i2c/mt9p031.h
> +++ b/include/media/i2c/mt9p031.h
> @@ -11,6 +11,7 @@ struct v4l2_subdev;
> struct mt9p031_platform_data {
> int ext_freq;
> int target_freq;
> + int resolution;
> };
>
> #endif

--
Regards,

Laurent Pinchart