Re: [PATCH v8 4/4] media: i2c: Add RDACM20 driver

From: Hans Verkuil <hverkuil@xs4all.nl>
To: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>,
	linux-renesas-soc@vger.kernel.org, linux-media@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: "Kieran Bingham" <kieran.bingham@ideasonboard.com>,
	"Laurent Pinchart" <laurent.pinchart@ideasonboard.com>,
	"Jacopo Mondi" <jacopo@jmondi.org>,
	"Niklas Söderlund" <niklas.soderlund@ragnatech.se>,
	sakari.ailus@iki.fi, "Hyun Kwon" <hyunk@xilinx.com>,
	"Manivannan Sadhasivam" <manivannan.sadhasivam@linaro.org>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Jacopo Mondi" <jacopo+renesas@jmondi.org>,
	"Laurent Pinchart" <laurent.pinchart+renesas@ideasonboard.com>,
	"Niklas Söderlund" <niklas.soderlund+renesas@ragnatech.se>,
	"Rob Herring" <robh@kernel.org>
Subject: Re: [PATCH v8 4/4] media: i2c: Add RDACM20 driver
Date: Mon, 11 May 2020 12:20:30 +0200	[thread overview]
Message-ID: <9542009f-7290-eec4-3190-9fc8dad6f214@xs4all.nl> (raw)
In-Reply-To: <20200417103424.5875-5-kieran.bingham+renesas@ideasonboard.com>

On 17/04/2020 12:34, Kieran Bingham wrote:
> From: Jacopo Mondi <jacopo+renesas@jmondi.org>
> 
> The RDACM20 is a GMSL camera supporting 1280x800 resolution images
> developed by IMI based on an Omnivision 10635 sensor and a Maxim MAX9271
> GMSL serializer.
> 
> The GMSL link carries power, control (I2C) and video data over a
> single coax cable.
> 
> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
> Reviewed-by: Rob Herring <robh@kernel.org>
> 
> ---

<snip>

> diff --git a/drivers/media/i2c/rdacm20.c b/drivers/media/i2c/rdacm20.c
> new file mode 100644
> index 000000000000..37786998878b
> --- /dev/null
> +++ b/drivers/media/i2c/rdacm20.c
> @@ -0,0 +1,668 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * IMI RDACM20 GMSL Camera Driver
> + *
> + * Copyright (C) 2017-2020 Jacopo Mondi
> + * Copyright (C) 2017-2020 Kieran Bingham
> + * Copyright (C) 2017-2019 Laurent Pinchart
> + * Copyright (C) 2017-2019 Niklas Söderlund
> + * Copyright (C) 2016 Renesas Electronics Corporation
> + * Copyright (C) 2015 Cogent Embedded, Inc.
> + */
> +
> +/*
> + * The camera is made of an Omnivision OV10635 sensor connected to a Maxim
> + * MAX9271 GMSL serializer.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/fwnode.h>
> +#include <linux/init.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/videodev2.h>
> +
> +#include <media/v4l2-async.h>
> +#include <media/v4l2-ctrls.h>
> +#include <media/v4l2-subdev.h>
> +
> +#include "max9271.h"
> +
> +#define OV10635_I2C_ADDRESS		0x30
> +
> +#define OV10635_SOFTWARE_RESET		0x0103
> +#define OV10635_PID			0x300a
> +#define OV10635_VER			0x300b
> +#define OV10635_SC_CMMN_SCCB_ID		0x300c
> +#define OV10635_SC_CMMN_SCCB_ID_SELECT	BIT(0)
> +#define OV10635_VERSION			0xa635
> +
> +#define OV10635_WIDTH			1280
> +#define OV10635_HEIGHT			800
> +#define OV10635_FORMAT			MEDIA_BUS_FMT_UYVY8_2X8

This OV10635_FORMAT define was very confusing when I reviewed this code.

Please just use MEDIA_BUS_FMT_UYVY8_2X8 directly instead of introducing
an alias. While reviewing I thought for a moment that OV10635_FORMAT was
somehow a new mediabus format that was added elsewhere. I had to dig into
the code to figure out that it really was an alias.

Regards,

	Hans