Hi HeungJun, On 01/02/2012 05:38 AM, Kim, Heungjun wrote: > On 2011년 12월 30일 19:30, Sylwester Nawrocki wrote: >> On 12/29/2011 06:08 AM, HeungJun, Kim wrote: >>> I guess the WBP menu controls of pwc driver is probably defined in the other >>> headers, for users being well known the PWC hardware. So it should be managed >>> separately to videodev2.h. Is it right? Even if the way might be slightly >>> different, it can't avoid to be "managed separately". >>> >>> It means the users being not well known the specific hardware like PWC, >>> have difficulty to use that driver well. >>> And, at least, It doesn't looks generic API for me. >>> In this case, the unfamiliar user with such unique hardware, can use >>> whatever he wants to use finally, after finding& looking around the headers. >> Applications can query drivers for supported controls and populate user control >> panels dynamically, based on information from VIDIOC_QUERYCTRL and >> VIDIOC_QUERYMENU >> ioctls. Not needing to rely on menu items definition in videodev2.h. >> I had a feeling you weren't considering such case. :) > You're right in that meaning. And it might be a good point. > But, I think these 2 ioctl can not handle about this issue. > > Before using VIDIOC_QUERYCTRL and VIDIOC_QUERYMENU, the user should know which > CID name > is used in the videodev2.h, and anyway it can not be avoidable the user find out > this name in it. :) Yes, in many cases it is required to know the CID in advance, however it is not mandatory for all applications. > At least I've seen nobody makes the application just to open(), queryctrl(), > querymenu(), and close(), > only for scanning the specific control is existed or not. > Until now, I have known these 2 ioctl is generally used for formating the UI > componets like button, menu, and etc, on the screen. Yup. > So, it's safe to say that the user who knows that specific control is also know > the CID name, > the user knows such specific controls don't need even VIDIOC_QUERYCTRL and > VIDIOC_QUERYMENU. I respectfully disagree. Properly written applications must use VIDIOC_QUERYCTRL/ VIDIOC_QUERYMENU ioctls, as many v4l2 controls have now driver-specific value range. Please see this application for instance [1], it doesn't hard code any control IDs in it, it only uses V4L2_CID_BASE, V4L2_CID_PRIVATE_BASE and V4L2_CID_LASTP1. Yet, it can handle any control, as long as it supports the control's type. > And IMHO, this is not related about pulling out the hidden(?) controls generally > used in the camera, > on the videodev2.h. I think it's only generic defined in videodev2.h. > > I really had wondered why the controls I thought very general for camera is in > hidden(?) the specific driver, > not in the videodev2.h. It was just start to consider this issues. I think you misunderstood me, I didn't mean to force anyone to use private controls for common features. :) > Regards, > Heungjun Kim > >> Perhaps it's uncommon in embedded systems though. [1] http://sourceforge.net/projects/v4l2ucp/files/v4l2ucp/2.0/ -- Regards, Sylwester -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
