From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from smtp.nokia.com ([147.243.1.47]:24390 "EHLO mgw-sa01.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933188Ab0J0Nsu (ORCPT ); Wed, 27 Oct 2010 09:48:50 -0400 Message-ID: <4CC82DBC.4020907@maxwell.research.nokia.com> Date: Wed, 27 Oct 2010 16:48:44 +0300 From: Sakari Ailus MIME-Version: 1.0 To: Michael Jones CC: Linux Media Mailing List , laurent.pinchart@ideasonboard.com Subject: Re: controls, subdevs, and media framework References: <4CC6EEDC.20206@matrix-vision.de> In-Reply-To: <4CC6EEDC.20206@matrix-vision.de> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit List-ID: Sender: Hi Michael, Michael Jones wrote: > Having settled on a particular video device, (how) do regular > controls (ie. VIDIOC_[S|G]_CTRL) work? I don't see any support for > them in ispvideo.c. Is it just yet to be implemented? Or is it > expected that the application will access the subdevs individually? The applications will access the subdevs independently. I'd expect that regular applications won't be interested in things like V4L2_CID_EXPOSURE (to manually set exposure value) since they'd more likely want automatic exposure. These interfaces (subdevs) can be used by specialised applications and libraries, most likely a general purpose application would not access them directly. For example, on N900 the automatic exposure algorithm is a user space beast, so that functionality cannot be implemented in kernel level at all. I'd expect general purpose applications to be using libv4l which will know how to handle the hardware, in future. > Basically the same Q for CROPCAP: isp_video_cropcap passes it on to > the last link in the chain, but none of the subdevs in the ISP > currently have a cropcap function implemented (yet). Does this still > need to be written? Setting and getting crop is supported but CROPCAP ioctl isn't actually even defined for subdevs. I don't think an ioctl similar to CROPCAP even makes sense since crop is so much more simple for subdevs. Every time I need to deal with CROPCAP I'll first have to go to read the specs. ;-) If there is hardware which has somehow limited crop capability then there might be a need for an ioctl to query the minimum possible size after crop. At least the OMAP 3 ISP can crop as much as you want. That shouldn't be a problem from hardware perspective as fas as I understand. Cheers, -- Sakari Ailus sakari.ailus@maxwell.research.nokia.com