From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-ee0-f46.google.com ([74.125.83.46]:62016 "EHLO mail-ee0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752551Ab1LaMDa (ORCPT ); Sat, 31 Dec 2011 07:03:30 -0500 Received: by eekc4 with SMTP id c4so14252766eek.19 for ; Sat, 31 Dec 2011 04:03:29 -0800 (PST) Message-ID: <4EFEFA08.805@gmail.com> Date: Sat, 31 Dec 2011 13:03:20 +0100 From: Sylwester Nawrocki MIME-Version: 1.0 To: Sakari Ailus CC: Scott Jiang , Hans Verkuil , Guennadi Liakhovetski , LMML Subject: Re: v4l: how to get blanking clock count? References: <20111230213301.GA3677@valkosipuli.localdomain> <20111231113529.GC3677@valkosipuli.localdomain> In-Reply-To: <20111231113529.GC3677@valkosipuli.localdomain> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: Hi Sakari, On 12/31/2011 12:35 PM, Sakari Ailus wrote: > On Sat, Dec 31, 2011 at 02:57:31PM +0800, Scott Jiang wrote: >> 2011/12/31 Sakari Ailus : >>> On Fri, Dec 30, 2011 at 03:20:43PM +0800, Scott Jiang wrote: >>>> Our bridge driver needs to know line clock count including active >>>> lines and blanking area. >>>> I can compute active clock count according to pixel format, but how >>>> can I get this in blanking area in current framework? >>> >>> Such information is not available currently over the V4L2 subdev interface. >>> Please see this patchset: >>> >>> >>> >>> Patches 7 and 8 are probably the most interesting for you. This is an RFC >>> patchset so the final implementation could well still change. >>> >> Hi Sakari, >> >> Thanks for your reply. Your patch added VBLANK and HBLANK control, but >> my case isn't a user control. >> That is to say, you can't specify a blanking control value for sensor. > > I the case of your bridge, that may not be possible, but that's the only one > I've heard of so I think it's definitely a special case. In that case the > sensor driver can't be allowed to change the blanking periods while > streaming is ongoing. I agree, it's just a matter of adding proper logic at the sensor driver. However it might be a bit tricky, the bridge would have to validate blanking values before actually enabling streaming. > framesamples proposed by Sylwester for v4l2_mbus_framefmt could, and > probably should, be exposed as a control with similar property. Yeah, I'm going to try to add it to your proposed image source control class. >> And you added pixel clock rate in mbus format, I think if I add two >> more parametres such as VBLANK lines and HBLANK clocks I can solve >> this problem. In fact, active lines and blanking lines are essential >> params to define an image. > > Only the active lines and rows are, blanking period is just an idle period > where no image data is transferred. It does not affect the resulting image > in any way. -- Regards, Sylwester