linux-kernel - Re: [PATCH v4 3/4] gpu: ipu-v3: ipu-ic: Add support for BT.709 encoding

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Date:   Tue, 12 Feb 2019 12:34:22 +0100
From:   Philipp Zabel <p.zabel@...gutronix.de>
To:     Steve Longerbeam <slongerbeam@...il.com>,
        linux-media@...r.kernel.org
Cc:     Tim Harvey <tharvey@...eworks.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        "open list:DRM DRIVERS FOR FREESCALE IMX" 
        <dri-devel@...ts.freedesktop.org>,
        open list <linux-kernel@...r.kernel.org>,
        "open list:STAGING SUBSYSTEM" <devel@...verdev.osuosl.org>,
        "open list:FRAMEBUFFER LAYER" <linux-fbdev@...r.kernel.org>
Subject: Re: [PATCH v4 3/4] gpu: ipu-v3: ipu-ic: Add support for BT.709
 encoding

Hi Steve,

On Mon, 2019-02-11 at 17:20 -0800, Steve Longerbeam wrote:
[...]
> > Should we support YUV BT.601 <-> YUV REC.709 conversions? That would
> > require separate encodings for input and output.
> 
> How about if we pass the input and output encodings to the init ic task 
> functions, but for now require they be the same? We can support 
> transcoding in a later series.
[...]
> Again, I think for now, just include input/output quantization but 
> require full range for RGB and limited range for YUV.

Yes, that is fine. I'd just like to avoid unnecessary interface changes
between ipu-v3 and imx-media. So if we have to change it right now, why
not plan ahead.

> But that really balloons the arguments to ipu_ic_task_init_*(). Should 
> we create an ipu_ic_task_init structure?

I wonder if we should just expose struct ic_csc_params and provide a
helper to fill it given colorspace and V4L2 encoding/quantization
parameters. Something like:

	struct ipu_ic_csc_params csc;

	imx_media_init_ic_csc_params(&csc,
			in_cs, in_encoding, in_quantization,
			out_cs, out_encoding, out_quantization);

	ipu_ic_task_init(ic,
			in_width, in_height,
			out_width, out_height, &csc);
	// or
	ipu_ic_task_init_rsc(ic, rsc, &csc);

regards
Philipp