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From:   Jernej =?utf-8?B?xaBrcmFiZWM=?= <jernej.skrabec@siol.net>
To:     a.hajda@samsung.com, Neil Armstrong <narmstrong@baylibre.com>
Cc:     Laurent.pinchart@ideasonboard.com, jonas@kwiboo.se,
        airlied@linux.ie, daniel@ffwll.ch, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/4] drm/bridge: dw-hdmi: Fix color space conversion detection
Date:   Mon, 02 Mar 2020 17:42:35 +0100
Message-ID: <1955232.bB369e8A3T@jernej-laptop>
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References: <20200229163043.158262-1-jernej.skrabec@siol.net> <20200229163043.158262-3-jernej.skrabec@siol.net> <c1cbcdc0-61a7-e5cb-4ad0-7057c33da154@baylibre.com>
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Dne ponedeljek, 02. marec 2020 ob 10:26:09 CET je Neil Armstrong napisal(a):
> Hi Jernej,
> 
> On 29/02/2020 17:30, Jernej Skrabec wrote:
> > Currently, is_color_space_conversion() compares not only color spaces
> > but also formats. For example, function would return true if YCbCr 4:4:4
> > and YCbCr 4:2:2 would be set. Obviously in that case color spaces are
> > the same.
> > 
> > Fix that by comparing if both values represent RGB color space.
> > 
> > Fixes: b21f4b658df8 ("drm: imx: imx-hdmi: move imx-hdmi to
> > bridge/dw_hdmi")
> > Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
> > ---
> > 
> >  drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> > b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c index
> > 24965e53d351..9d7bfb1cb213 100644
> > --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> > +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> > @@ -956,7 +956,8 @@ static void hdmi_video_sample(struct dw_hdmi *hdmi)
> > 
> >  static int is_color_space_conversion(struct dw_hdmi *hdmi)
> >  {
> > 
> > -	return hdmi->hdmi_data.enc_in_bus_format !=
> > hdmi->hdmi_data.enc_out_bus_format; +	return
> > hdmi_bus_fmt_is_rgb(hdmi->hdmi_data.enc_in_bus_format) !=
> > +		hdmi_bus_fmt_is_rgb(hdmi-
>hdmi_data.enc_out_bus_format);
> > 
> >  }
> >  
> >  static int is_color_space_decimation(struct dw_hdmi *hdmi)
> 
> I think in this case you should also fix the CEC enablement to:
> if (is_color_space_conversion(hdmi) || is_color_space_decimation(hdmi))
> 
> in dw_hdmi_enable_video_path() otherwise CSC won't be enabled and will be
> bypassed in decimation case only.

On second thought, I think original implementation is correct, just misnamed. 
Laurent, Neil, do you agree if I replace this patch with patch which renames 
is_color_space_conversion() to is_conversion_needed() ?

Best regards,
Jernej