From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mailout2.w1.samsung.com ([210.118.77.12]:28964 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753705Ab1IUNY1 (ORCPT ); Wed, 21 Sep 2011 09:24:27 -0400 Received: from euspt1 (mailout2.w1.samsung.com [210.118.77.12]) by mailout2.w1.samsung.com (iPlanet Messaging Server 5.2 Patch 2 (built Jul 14 2004)) with ESMTP id <0LRV003FUJWPKU@mailout2.w1.samsung.com> for linux-media@vger.kernel.org; Wed, 21 Sep 2011 14:24:25 +0100 (BST) Received: from linux.samsung.com ([106.116.38.10]) by spt1.w1.samsung.com (iPlanet Messaging Server 5.2 Patch 2 (built Jul 14 2004)) with ESMTPA id <0LRV00JKZJWP67@spt1.w1.samsung.com> for linux-media@vger.kernel.org; Wed, 21 Sep 2011 14:24:25 +0100 (BST) Date: Wed, 21 Sep 2011 15:24:24 +0200 From: Sylwester Nawrocki Subject: Re: [PATCH v3 1/2] v4l2: Add the polarity flags for parallel camera bus FIELD signal In-reply-to: <201109210112.39469.laurent.pinchart@ideasonboard.com> To: Laurent Pinchart Cc: linux-media@vger.kernel.org, kyungmin.park@samsung.com, m.szyprowski@samsung.com, g.liakhovetski@gmx.de, sw0312.kim@samsung.com, riverful.kim@samsung.com Message-id: <4E79E588.4000608@samsung.com> MIME-version: 1.0 Content-type: text/plain; charset=ISO-8859-15 Content-transfer-encoding: 7BIT References: <1316450497-6723-1-git-send-email-s.nawrocki@samsung.com> <1316452075-10700-1-git-send-email-s.nawrocki@samsung.com> <201109210112.39469.laurent.pinchart@ideasonboard.com> Sender: linux-media-owner@vger.kernel.org List-ID: Hi Laurent, On 09/21/2011 01:12 AM, Laurent Pinchart wrote: > Hi Sylwester, > > Thanks for the patch. > > On Monday 19 September 2011 19:07:55 Sylwester Nawrocki wrote: >> FIELD is an Even/Odd field selection signal, as specified in ITU-R BT.601 >> standard. Add corresponding flag for configuring the FIELD signal polarity. >> Also add a comment about usage of V4L2_MBUS_[HV]SYNC* flags for the >> hardware that uses [HV]REF signals. > > I like this approach better. > ... >> +/* Field selection signal for interlaced scan mode */ >> +#define V4L2_MBUS_FIELD_ACTIVE_HIGH (1 << 10) >> +#define V4L2_MBUS_FIELD_ACTIVE_LOW (1 << 11) > > What does this mean ? The FIELD signal is used to select between odd and even > fields. Does "active high" mean that the field is odd or even when the signal > has a high level ? The comment should make it explicit, or we could even > rename those two constants to FIELD_ODD_HIGH/FIELD_ODD_LOW (or > FIELD_EVEN_HIGH/FIELD_EVEN_LOW). Yes, certainly I didn't think enough about this. I silently assumed that for V4L2_MBUS_FIELD_ACTIVE_HIGH FIELD = 0 selects Field1 (odd) and FIELD = 1 selects Field2 (even). I think it would be good to construct the macro so it is possibly self-explanatory, rather than requiring often to dig in the documentation. So I would go for V4L2_MBUS_FIELD_ODD_LOW/V4L2_MBUS_FIELD_ODD_HIGH. Unless someone proposes something different/better I'll send an amended version tomorrow. Thanks, -- Sylwester Nawrocki Samsung Poland R&D Center