Re: [PATCH v2 2/3] media: cedrus: Fix H264 default reference index count

From: "Jernej Škrabec" <jernej.skrabec@siol.net>
To: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Cc: mripard@kernel.org, mchehab@kernel.org, hverkuil-cisco@xs4all.nl,
	gregkh@linuxfoundation.org, wens@csie.org,
	linux-media@vger.kernel.org, devel@driverdev.osuosl.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/3] media: cedrus: Fix H264 default reference index count
Date: Thu, 03 Oct 2019 07:16:09 +0200	[thread overview]
Message-ID: <12199603.8LrTjBMqpV@jernej-laptop> (raw)
In-Reply-To: <20191002220650.GB24151@aptenodytes>

Dne četrtek, 03. oktober 2019 ob 00:06:50 CEST je Paul Kocialkowski 
napisal(a):
> Hi,
> 
> On Wed 02 Oct 19, 21:35, Jernej Skrabec wrote:
> > Reference index count in VE_H264_PPS should come from PPS control.
> > However, this is not really important, because reference index count is
> > in our case always overridden by that from slice header.
> 
> Thanks for the fixup!
> 
> Our libva userspace and v4l2-request testing tool currently don't provide
> this, but I have a pending merge request adding it for the hantro so it's
> good to go.

Actually, I think this is just cosmetic and it would work even if it would be 
always 0. We always override this number in SHS2 register with 
VE_H264_SHS2_NUM_REF_IDX_ACTIVE_OVRD flag and recently there was a patch merged 
to clarify that value in slice parameters should be the one that's set on 
default value if override flag is not set in bitstream:
https://git.linuxtv.org/media_tree.git/commit/?
id=187ef7c5c78153acdce8c8714e5918b1018c710b

Well, we could always compare default and value in slice parameters, but I 
really don't see the benefit of doing that extra work.

Best regards,
Jernej

> 
> Acked-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> 
> Cheers,
> 
> Paul
> 
> > Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
> > ---
> > 
> >  drivers/staging/media/sunxi/cedrus/cedrus_h264.c | 8 ++------
> >  1 file changed, 2 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
> > b/drivers/staging/media/sunxi/cedrus/cedrus_h264.c index
> > bd848146eada..4a0e69855c7f 100644
> > --- a/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
> > +++ b/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
> > @@ -364,12 +364,8 @@ static void cedrus_set_params(struct cedrus_ctx *ctx,
> > 
> >  	// picture parameters
> >  	reg = 0;
> > 
> > -	/*
> > -	 * FIXME: the kernel headers are allowing the default value to
> > -	 * be passed, but the libva doesn't give us that.
> > -	 */
> > -	reg |= (slice->num_ref_idx_l0_active_minus1 & 0x1f) << 10;
> > -	reg |= (slice->num_ref_idx_l1_active_minus1 & 0x1f) << 5;
> > +	reg |= (pps->num_ref_idx_l0_default_active_minus1 & 0x1f) << 10;
> > +	reg |= (pps->num_ref_idx_l1_default_active_minus1 & 0x1f) << 5;
> > 
> >  	reg |= (pps->weighted_bipred_idc & 0x3) << 2;
> >  	if (pps->flags & V4L2_H264_PPS_FLAG_ENTROPY_CODING_MODE)
> >  	
> >  		reg |= VE_H264_PPS_ENTROPY_CODING_MODE;