linux-kernel - Re: [PATCH 3/9] drm/vc4: hdmi: Add Broadcast RGB property to allow override of RGB range

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Message-ID: <20230126093853.kqjhswl27kelywov@houat>
Date:   Thu, 26 Jan 2023 10:38:53 +0100
From:   Maxime Ripard <maxime@...no.tech>
To:     Thomas Zimmermann <tzimmermann@...e.de>
Cc:     Emma Anholt <emma@...olt.net>, David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org,
        Dave Stevenson <dave.stevenson@...pberrypi.com>
Subject: Re: [PATCH 3/9] drm/vc4: hdmi: Add Broadcast RGB property to allow
 override of RGB range

Hi,

Thanks for your review

On Wed, Jan 11, 2023 at 03:11:51PM +0100, Thomas Zimmermann wrote:
> Am 07.12.22 um 17:07 schrieb Maxime Ripard:
> > From: Dave Stevenson <dave.stevenson@...pberrypi.com>
> > 
> > Copy Intel's "Broadcast RGB" property semantics to add manual override
> > of the HDMI pixel range for monitors that don't abide by the content
> > of the AVI Infoframe.
> > 
> > Signed-off-by: Dave Stevenson <dave.stevenson@...pberrypi.com>
> > Signed-off-by: Maxime Ripard <maxime@...no.tech>
> > ---
> >   drivers/gpu/drm/vc4/vc4_hdmi.c | 87 ++++++++++++++++++++++++++++++++++++++++++
> >   drivers/gpu/drm/vc4/vc4_hdmi.h | 15 ++++++++
> >   2 files changed, 102 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
> > index 0eafaf0b76e5..488a4012d422 100644
> > --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> > +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> > @@ -154,6 +154,11 @@ static bool vc4_hdmi_is_full_range_rgb(struct vc4_hdmi *vc4_hdmi,
> >   {
> >   	struct drm_display_info *display = &vc4_hdmi->connector.display_info;
> > +	if (vc4_hdmi->broadcast_rgb == VC4_HDMI_BROADCAST_RGB_LIMITED)
> > +		return false;
> > +	else if (vc4_hdmi->broadcast_rgb == VC4_HDMI_BROADCAST_RGB_FULL)
> > +		return true;
> > +
> >   	return !display->is_hdmi ||
> >   		drm_default_rgb_quant_range(mode) == HDMI_QUANTIZATION_RANGE_FULL;
> 
> The existing code is now the branch for VC4_HDMI_BROADCAST_RGB_AUTO, AFAIU.

I'm not entirely sure what you meant here sorry. The existing code path
is indeed the VC4_HDMI_BROADCAST_RGB_AUTO case, which is the property
default so the current behaviour should remain by default.

Is there anything you want me to clarify?

Maxime