On Thu 6 December 2012 10:54:32 Sakari Ailus wrote: > Hi Prabhakar and Hans, > > On Thu, Dec 06, 2012 at 10:24:18AM +0530, Prabhakar Lad wrote: > > Hi Hans, > > > > On Wed, Dec 5, 2012 at 5:38 PM, Hans Verkuil <hverkuil@xxxxxxxxx> wrote: > > > (resend without HTML formatting) > > > > > > On Wed 5 December 2012 12:49:29 Prabhakar Lad wrote: > > >> From: Lad, Prabhakar <prabhakar.csengg@xxxxxxxxx> > > >> > > >> add support for per color component digital/analog gain controls > > >> and also their corresponding offset. > > > > > > Some obvious questions below... > > > > > >> > > >> Signed-off-by: Lad, Prabhakar <prabhakar.csengg@xxxxxxxxx> > > >> Cc: Sakari Ailus <sakari.ailus@xxxxxx> > > >> Cc: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> > > >> Cc: Kyungmin Park <kyungmin.park@xxxxxxxxxxx> > > >> Cc: Guennadi Liakhovetski <g.liakhovetski@xxxxxx> > > >> Cc: Sylwester Nawrocki <s.nawrocki@xxxxxxxxxxx> > > >> Cc: Hans Verkuil <hans.verkuil@xxxxxxxxx> > > >> Cc: Hans de Goede <hdegoede@xxxxxxxxxx> > > >> Cc: Chris MacGregor <chris@xxxxxxxxxxxxx> > > >> Cc: Rob Landley <rob@xxxxxxxxxxx> > > >> Cc: Jeongtae Park <jtp.park@xxxxxxxxxxx> > > >> Cc: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxx> > > >> --- > > >> Changes for v2: > > >> 1: Fixed review comments pointed by Laurent. > > >> 2: Rebased on latest tree. > > >> > > >> Documentation/DocBook/media/v4l/controls.xml | 54 ++++++++++++++++++++++++++ > > >> drivers/media/v4l2-core/v4l2-ctrls.c | 11 +++++ > > >> include/uapi/linux/v4l2-controls.h | 11 +++++ > > >> 3 files changed, 76 insertions(+), 0 deletions(-) > > >> > > >> diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml > > >> index 7fe5be1..847a9bb 100644 > > >> --- a/Documentation/DocBook/media/v4l/controls.xml > > >> +++ b/Documentation/DocBook/media/v4l/controls.xml > > >> @@ -4543,6 +4543,60 @@ interface and may change in the future.</para> > > >> specific test patterns can be used to test if a device is working > > >> properly.</entry> > > >> </row> > > >> + <row> > > >> + <entry spanname="id"><constant>V4L2_CID_GAIN_RED</constant></entry> > > >> + <entry>integer</entry> > > >> + </row> > > >> + <row> > > >> + <entry spanname="id"><constant>V4L2_CID_GAIN_GREEN_RED</constant></entry> > > >> + <entry>integer</entry> > > >> + </row> > > >> + <row> > > >> + <entry spanname="id"><constant>V4L2_CID_GAIN_GREEN_BLUE</constant></entry> > > >> + <entry>integer</entry> > > >> + </row> > > >> + <row> > > >> + <entry spanname="id"><constant>V4L2_CID_GAIN_BLUE</constant></entry> > > >> + <entry>integer</entry> > > >> + </row> > > >> + <row> > > >> + <entry spanname="id"><constant>V4L2_CID_GAIN_GREEN</constant></entry> > > >> + <entry>integer</entry> > > >> + </row> > > >> + <row> > > >> + <entry spanname="descr"> Some capture/sensor devices have > > >> + the capability to set per color component digital/analog gain values.</entry> > > >> + </row> > > >> + <row> > > >> + <entry spanname="id"><constant>V4L2_CID_GAIN_OFFSET</constant></entry> > > >> + <entry>integer</entry> > > >> + </row> > > >> + <row> > > >> + <entry spanname="id"><constant>V4L2_CID_BLUE_OFFSET</constant></entry> > > >> + <entry>integer</entry> > > >> + </row> > > >> + <row> > > >> + <entry spanname="id"><constant>V4L2_CID_RED_OFFSET</constant></entry> > > >> + <entry>integer</entry> > > >> + </row> > > >> + <row> > > >> + <entry spanname="id"><constant>V4L2_CID_GREEN_OFFSET</constant></entry> > > >> + <entry>integer</entry> > > >> + </row> > > >> + <row> > > >> + <entry spanname="id"><constant>V4L2_CID_GREEN_RED_OFFSET</constant></entry> > > >> + <entry>integer</entry> > > >> + </row> > > >> + <row> > > >> + <entry spanname="id"><constant>V4L2_CID_GREEN_BLUE_OFFSET</constant></entry> > > >> + <entry>integer</entry> > > >> + </row> > > >> + <row> > > >> + <entry spanname="descr"> Some capture/sensor devices have the > > >> + capability to set per color component digital/analog gain offset values. > > >> + V4L2_CID_GAIN_OFFSET is the global gain offset and the rest are per > > >> + color component gain offsets.</entry> > > > > > > If I set both V4L2_CID_GAIN_RED and V4L2_CID_RED_OFFSET, how are they supposed > > > to interact? Or are they mutually exclusive? > > > > > > And if I set both V4L2_CID_GAIN_OFFSET and V4L2_CID_RED_OFFSET, how are they supposed > > > to interact? > > > > > > This questions should be answered in the documentation... > > > > > I haven’t worked on the hardware which supports both, What is the general > > behaviour when the hardware supports both per color component and global > > and both of them are set ? That could be helpful for me to document. > > I'd guess most of the time only either one is supported, Are you talking about GAIN_RED vs GAIN_RED_OFFSET or GAIN_OFFSET vs RED_OFFSET? Or both? > and when someone > thinks of supporting both on the same device, we can start thinking of the > interaction of per-component and global ones. That may be hardware specific > as well, so standardising it might not be possible. > > I think it'd be far more important to know which unit is it. Many such > controls are indeed fixed point values but the location of the point varies. > For unstance, u16,u16 and u8,u8 aren't uncommon. We currently have no way to > tell this to the user space. This isn't in any way specific to gain or > offset controls, though. There are no standardized units for gain at the moment, and I don't really see that happening any time soon. Fixed point isn't supported at all as a control type, so that will have to be converted to an integer anyway. Prabhakar, which of these controls are actually supported by your hardware? Regards, Hans -- 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
