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From: Sakari Ailus <sakari.ailus@iki.fi>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: "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>,
	"Kieran Bingham" <kieran.bingham@ideasonboard.com>,
	"Jacopo Mondi" <jacopo@jmondi.org>,
	"Niklas Söderlund" <niklas.soderlund@ragnatech.se>,
	"Hans Verkuil" <hverkuil@xs4all.nl>,
	"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>
Subject: Re: [PATCH v9 2/4] media: i2c: Add MAX9286 driver
Date: Tue, 26 May 2020 11:54:50 +0300	[thread overview]
Message-ID: <20200526085450.GF8214@valkosipuli.retiisi.org.uk> (raw)
In-Reply-To: <20200520005020.GQ3820@pendragon.ideasonboard.com>

Hi Laurent,

On Wed, May 20, 2020 at 03:50:20AM +0300, Laurent Pinchart wrote:
> Hi Sakari,
> 
> On Mon, May 18, 2020 at 12:45:18PM +0100, Kieran Bingham wrote:
> > Hi Sakari,
> > 
> > There are only fairly minor comments here, fix ups will be included in a
> > v10.
> > 
> > Is there anything major blocking integration?
> > 
> > On 16/05/2020 22:51, Sakari Ailus wrote:
> > > On Tue, May 12, 2020 at 04:51:03PM +0100, Kieran Bingham wrote:
> > > 
> > > ...
> > > 
> > >> +static int max9286_enum_mbus_code(struct v4l2_subdev *sd,
> > >> +				  struct v4l2_subdev_pad_config *cfg,
> > >> +				  struct v4l2_subdev_mbus_code_enum *code)
> > >> +{
> > >> +	if (code->pad || code->index > 0)
> > >> +		return -EINVAL;
> > >> +
> > >> +	code->code = MEDIA_BUS_FMT_UYVY8_2X8;
> > > 
> > > Why UYVY8_2X8 and not UYVY8_1X16? In general, the single sample / pixel
> > > variant of the format is generally used on the serial busses. This choice
> > > was made when serial busses were introduced.
> 
> This is a bit of a tricky one. On the camera size, for the RDACM20, the
> O10635 sensor outputs UYVY8_2X8. This if fed to the MAX9271 serializer,
> which doesn't care about the data type. The MAX9271 has a 16-bit input
> bus, with 10 bits reserved for data, 2 bits dynamically configurable
> to carry H/V sync or extra data, and 4 bits dynamically configurable to
> carry GPIOs or extra data. The 16-bit words are then serialized (it's a
> bit more complicated, when using the H/V sync signals they are
> transmitted in a different way, and the MAX9271 also supports a DDR mode
> that makes the "serial link word" carry up to 30 bits). Effectively, the
> two samples of UYVY8_2X8 are serialized in a 16-bit word each.
> 
> Sakari, with this information in mind, what would you recommend ?

As this pad describes a serial bus --- doesn't it? --- it should use the
same formats as other serial busses such as CSI-2. I.e. the 1X16 variant.

-- 
Regards,

Sakari Ailus

  reply	other threads:[~2020-05-26  8:55 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-12 15:51 [PATCH v9 0/4] MAX9286 GMSL Support (+RDACM20) Kieran Bingham
2020-05-12 15:51 ` [PATCH v9 1/4] dt-bindings: media: i2c: Add bindings for Maxim Integrated MAX9286 Kieran Bingham
2020-05-12 22:33   ` Rob Herring
2020-05-12 22:36   ` Rob Herring
2020-05-13 12:28     ` Jacopo Mondi
2020-05-12 15:51 ` [PATCH v9 2/4] media: i2c: Add MAX9286 driver Kieran Bingham
2020-05-12 17:40   ` Manivannan Sadhasivam
2020-05-14  9:53     ` Kieran Bingham
2020-05-14  9:59       ` Manivannan Sadhasivam
2020-05-14 10:05         ` Kieran Bingham
2020-05-12 18:17   ` Manivannan Sadhasivam
2020-05-14 10:02     ` Kieran Bingham
2020-05-14 10:13       ` Manivannan Sadhasivam
2020-05-14 11:47         ` Kieran Bingham
2020-05-14 11:59           ` Geert Uytterhoeven
2020-05-14 12:48             ` Manivannan Sadhasivam
2020-05-14 13:50               ` Kieran Bingham
2020-05-14 11:47         ` Kieran Bingham
2020-05-14 12:27           ` Kieran Bingham
2020-05-14 12:54             ` Manivannan Sadhasivam
2020-05-16 21:51   ` Sakari Ailus
2020-05-18 11:45     ` Kieran Bingham
2020-05-18 12:38       ` Jacopo Mondi
2020-05-18 13:09         ` Kieran Bingham
2020-05-19  8:10       ` Sakari Ailus
2020-05-19  8:55         ` Kieran Bingham
2020-05-19  9:03           ` Sakari Ailus
2020-05-20  0:50       ` Laurent Pinchart
2020-05-26  8:54         ` Sakari Ailus [this message]
2020-05-12 15:51 ` [PATCH v9 3/4] dt-bindings: media: i2c: Add bindings for IMI RDACM2x Kieran Bingham
2020-05-12 15:51 ` [PATCH v9 4/4] media: i2c: Add RDACM20 driver Kieran Bingham
2020-05-16 22:36   ` Sakari Ailus
2020-05-18  7:35     ` Jacopo Mondi

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