Re: [PATCH v2 15/16] media: i2c: ov9282: Add support for 8bit readout

[Alexander Stein <alexander.stein@ew.tq-group.com>]

Hi Kieran,

Am Dienstag, 1. November 2022, 21:37:09 CET schrieb Kieran Bingham:
> Hi Alex,
> 
> Quoting Dave Stevenson (2022-11-01 18:20:47)
> 
> > Hi Alexander
> > 
> > On Tue, 1 Nov 2022 at 15:04, Alexander Stein
> > 
> > <alexander.stein@ew.tq-group.com> wrote:
> > > Hi Dave,
> > > 
> > > thanks for the fast reply.
> > > 
> > > Am Dienstag, 1. November 2022, 14:47:16 CET schrieb Dave Stevenson:
> > > > Hi Alexander
> > > > 
> > > > On Tue, 1 Nov 2022 at 11:59, Alexander Stein
> 
> <snip>
> 
> > > > > Using this series I was able to do some camera playback on LVDS
> > > > > display on
> > > > > imx8mm based platform (TQMa8MxML). My command was 'gst-launch-1.0
> > > > > v4l2src
> > > > > device=/dev/video0 ! video/x-
> > > > > raw,format=GRAY8,bpp=8,width=1280,height=720,framerate=30/1 !
> > > > > videoconvert
> > > > > ! waylandsink'
> > > > > But due to SW colorspace conversion this is awfully slow.
> > > > > Using a testsink I get about 72FPS on 1280x720 for GREY. Is this to
> > > > > be
> > > > > expected?
> > > > > I used 'gst-launch-1.0 v4l2src device=/dev/video0 ! video/x-
> > > > > raw,format=GRAY8,bpp=8,width=1280,height=720,framerate=30/1 !
> > > > > fpsdisplaysink video-sink="testsink" text-overlay=false silent=false
> > > > > sync=false -v' for that.
> > > > 
> > > > AFAIK v4l2src doesn't map from a caps framerate=30/1 to the relevant
> > > > V4L2_CID_VBLANK and V4L2_CID_HBLANK controls used by raw sensors for
> > > > frame rate control (see docs at [1]). The sensor will therefore stream
> > > > at whatever rate the controls get left at.
> > > 
> > > Yes I noticed the framerate caps has no effect. But I lack some kind of
> > > reference system to decide what should work and what not.
> > 
> > As per the docs link, raw sensors will be using the HBLANK and VBLANK
> > controls, not VIDIOC_S_PARM.
> > I don't know whether the GStreamer folks wish to add support to
> > v4l2src to set those - libcamerasrc is going to be the more normal
> > user of these sensors, but that generally means needing an ISP of some
> > form. With just v4l2src you've got no AE / AGC control loops, so it is
> > only of use in controlled lighting conditions.
> > 
> > I don't know the full details of the imx8 range, but believe the
> > libcamera folk were working with one of the imx8 platforms.
> 
> We have the i.MX8MP working with the ISP available on that variant. I
> think we can also anticipate some support for other i.MX8 ranges with a
> GPU based 'ISP' in the (nearish) future, but I don't know what the
> timescales will be yet.

You are referring to (mainly) Paul Elder's patches to rkisp1, right? I noticed 
them, but didn't get a chance for testing.

I noticed that using 'glupload ! glcolorconvert ! glcolorscale ! 
glcolorconvert ! gldownload' in a gstreamer Pipeline for converting Y8/GREY to 
RGBA doesn't work, because mesa rejects creating appropriate EGL buffers due 
to lack of some hardware features.

Best regards,
Alexander