From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from relay1.mentorg.com ([192.94.38.131]:62531 "EHLO relay1.mentorg.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757207AbcGJWe2 (ORCPT ); Sun, 10 Jul 2016 18:34:28 -0400 Subject: Re: [PATCH 06/11] media: adv7180: add bt.656-4 OF property To: Hans Verkuil , Ian Arkver , Lars-Peter Clausen References: <1467846004-12731-1-git-send-email-steve_longerbeam@mentor.com> <1467846004-12731-7-git-send-email-steve_longerbeam@mentor.com> <577E6C98.3020608@metafoo.de> <5781497A.2080804@gmail.com> <5781685C.7040907@mentor.com> <57816E47.90102@mentor.com> <57823B25.5070709@metafoo.de> <93d03258-d145-0a46-44a9-3c1d6f67873e@xs4all.nl> <8be92278-e1e1-fdf8-b11f-54054ae9a8ca@gmail.com> <557f0160-11a0-36c8-c303-c4626f81df45@xs4all.nl> CC: From: Steve Longerbeam Message-ID: <5782CD6F.4020202@mentor.com> Date: Sun, 10 Jul 2016 15:34:23 -0700 MIME-Version: 1.0 In-Reply-To: <557f0160-11a0-36c8-c303-c4626f81df45@xs4all.nl> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: On 07/10/2016 07:30 AM, Hans Verkuil wrote: > On 07/10/2016 04:17 PM, Ian Arkver wrote: >> On 10/07/16 13:55, Hans Verkuil wrote: >>> On 07/10/2016 02:10 PM, Lars-Peter Clausen wrote: >>>> On 07/09/2016 11:36 PM, Steve Longerbeam wrote: >>>>> On 07/09/2016 02:10 PM, Steve Longerbeam wrote: >>>>>> On 07/09/2016 11:59 AM, Steve Longerbeam wrote: >>>>>>> On 07/07/2016 07:52 AM, Lars-Peter Clausen wrote: >>>>>>>> On 07/07/2016 12:59 AM, Steve Longerbeam wrote: >>>>>>>>> Add a device tree boolean property "bt656-4" to allow setting >>>>>>>>> the ITU-R BT.656-4 compatible bit. >>>>>>>>> >>>>>>>>> Signed-off-by: Steve Longerbeam >>>>>>>> + /* select ITU-R BT.656-4 compatible? */ >>> Please don't use the '-4': BT.656 is sufficient. The -4 is just the version >>> number of the standard (and 5 is the latest anyway). >> From the ADV7180 DS [1]: >> >> BT.656-4, ITU-R BT.656-4 Enable, Address 0x04[7] >> >> Between Revision 3 and Revision 4 of the ITU-R BT.656 standards, the ITU >> has changed the toggling position for the V bit within the SAV EAV codes >> for NTSC. The ITU-R BT.656-4 standard bit allows the user to select an >> output mode that is compliant with either the previous or new standard. >> For further information, visit the International Telecommunication Union >> website. >> >> Note that the standard change only affects NTSC and has no bearing on PAL. >> >> When ITU-R BT.656-4 is 0 (default), the ITU-R BT.656-3 specification is >> used. The V bit goes low at EAV of Line 10 and Line 273. >> >> When ITU-R BT.656-4 is 1, the ITU-R BT.656-4 specification is used. The >> V bit goes low at EAV of Line 20 and Line 283. >> >> [1]www.analog.com/media/en/technical-documentation/data-sheets/*ADV7180*.pdf > Rev 4 came in in 1998. I would say that that is the default. We have had any > problems with this and I would need some proof that this is really needed. Hi Hans, yeah I agree with you that new capture drivers should not expect BT.656-3 compatible buss' any longer. The problem with i.MX6 however, is that the IPU CSI CCIR_CODE registers, which inform the IPU about the AV code positions, are very poorly documented. In order for i.MX6 to support BT.656-4 it would require very time-consuming reverse engineering to find the right values to plug into those registers to conform to the BT.656-4 AV code positions. Steve