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Date: Tue, 11 Dec 2012 15:02:53 +0530 From: Prabhakar Lad <prabhakar.csengg@...il.com> To: Hans Verkuil <hverkuil@...all.nl> Cc: Sakari Ailus <sakari.ailus@....fi>, LMML <linux-media@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>, LDOC <linux-doc@...r.kernel.org>, Laurent Pinchart <laurent.pinchart@...asonboard.com>, Kyungmin Park <kyungmin.park@...sung.com>, Guennadi Liakhovetski <g.liakhovetski@....de>, Sylwester Nawrocki <s.nawrocki@...sung.com>, Hans Verkuil <hans.verkuil@...co.com>, Hans de Goede <hdegoede@...hat.com>, Chris MacGregor <chris@...ermato.com>, Rob Landley <rob@...dley.net>, Jeongtae Park <jtp.park@...sung.com>, Mauro Carvalho Chehab <mchehab@...radead.org> Subject: Re: [PATCH RFC v2] media: v4l2-ctrl: Add gain controls Hi Hans, On Tue, Dec 11, 2012 at 2:26 PM, Hans Verkuil <hverkuil@...all.nl> wrote: > 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@...all.nl> wrote: >> > > (resend without HTML formatting) >> > > >> > > On Wed 5 December 2012 12:49:29 Prabhakar Lad wrote: >> > >> From: Lad, Prabhakar <prabhakar.csengg@...il.com> >> > >> >> > >> 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@...il.com> >> > >> Cc: Sakari Ailus <sakari.ailus@....fi> >> > >> Cc: Laurent Pinchart <laurent.pinchart@...asonboard.com> >> > >> Cc: Kyungmin Park <kyungmin.park@...sung.com> >> > >> Cc: Guennadi Liakhovetski <g.liakhovetski@....de> >> > >> Cc: Sylwester Nawrocki <s.nawrocki@...sung.com> >> > >> Cc: Hans Verkuil <hans.verkuil@...co.com> >> > >> Cc: Hans de Goede <hdegoede@...hat.com> >> > >> Cc: Chris MacGregor <chris@...ermato.com> >> > >> Cc: Rob Landley <rob@...dley.net> >> > >> Cc: Jeongtae Park <jtp.park@...sung.com> >> > >> Cc: Mauro Carvalho Chehab <mchehab@...radead.org> >> > >> --- >> > >> 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? > my hardware supports gain red, gain blue, gain green red, gain green blue and global gain offset. Regards, --Prabhakar Lad > Regards, > > Hans -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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