linux-kernel - Re: [PATCH v5] media: i2c: tvp7002: add OF support

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Date:	Fri, 23 Aug 2013 19:25:23 +0200
From:	Sylwester Nawrocki <s.nawrocki@...sung.com>
To:	Kumar Gala <galak@...eaurora.org>
Cc:	"Lad, Prabhakar" <prabhakar.csengg@...il.com>,
	LMML <linux-media@...r.kernel.org>,
	Hans Verkuil <hverkuil@...all.nl>,
	DLOS <davinci-linux-open-source@...ux.davincidsp.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Mauro Carvalho Chehab <m.chehab@...sung.com>,
	devicetree-discuss@...ts.ozlabs.org, linux-doc@...r.kernel.org
Subject: Re: [PATCH v5] media: i2c: tvp7002: add OF support

On 08/13/2013 03:00 AM, Kumar Gala wrote:
> On Aug 11, 2013, at 1:25 AM, Lad, Prabhakar wrote:
> 
>> From: "Lad, Prabhakar" <prabhakar.csengg@...il.com>
>>
>> add OF support for the tvp7002 driver.
>>
>> Signed-off-by: Lad, Prabhakar <prabhakar.csengg@...il.com>
>> ---
[...]
>> .../devicetree/bindings/media/i2c/tvp7002.txt      |   53 ++++++++++++++++
>> drivers/media/i2c/tvp7002.c                        |   67 ++++++++++++++++++--
>> 2 files changed, 113 insertions(+), 7 deletions(-)
>> create mode 100644 Documentation/devicetree/bindings/media/i2c/tvp7002.txt
>>
>> diff --git a/Documentation/devicetree/bindings/media/i2c/tvp7002.txt b/Documentation/devicetree/bindings/media/i2c/tvp7002.txt
>> new file mode 100644
>> index 0000000..5f28b5d
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/media/i2c/tvp7002.txt
>> @@ -0,0 +1,53 @@
>> +* Texas Instruments TV7002 video decoder
>> +
>> +The TVP7002 device supports digitizing of video and graphics signal in RGB and
>> +YPbPr color space.
>> +
>> +Required Properties :
>> +- compatible : Must be "ti,tvp7002"
>> +
>> +Optional Properties:
> 
> 
>> +- hsync-active: HSYNC Polarity configuration for the bus. Default value when
>> +  this property is not specified is <0>.
>> +
>> +- vsync-active: VSYNC Polarity configuration for the bus. Default value when
>> +  this property is not specified is <0>.
>> +
>> +- pclk-sample: Clock polarity of the bus. Default value when this property is
>> +  not specified is <0>.
>> +
>> +- sync-on-green-active: Active state of Sync-on-green signal property of the
>> +  endpoint.
>> +  0 = Normal Operation (Active Low, Default)
>> +  1 = Inverted operation
> 
> These seems better than what you have in video-interfaces.txt

We probably should specify default values in in the common binding description.
Then duplication could be avoided. Not sure if it's not too late for this, all
drivers would need to have same default values.

What's normal and what's inverted depends on a particular device.

>> +- field-even-active: Active-high Field ID output polarity control of the bus.
>> +  Under normal operation, the field ID output is set to logic 1 for an odd field
>> +  (field 1) and set to logic 0 for an even field (field 0).
>> +  0 = Normal Operation (Active Low, Default)
>> +  1 = FID output polarity inverted
>> +
> 
> Why the duplication if this is covered in video-interfaces.txt?

Yes, it would be better to avoid redefining these properties in each specific 
device's binding. Presumably, for easier matching of DT properties with the
hardware's description, we could only say in device specific document which
value of a property corresponds to "normal" and which to "inverted" operation ?
 
>> +For further reading of port node refer Documentation/devicetree/bindings/media/
>> +video-interfaces.txt.

-- 
Sylwester Nawrocki
Samsung R&D Institute Poland
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