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Date:   Wed, 26 Aug 2020 19:24:58 +0300
From:   Ville =?iso-8859-1?Q?Syrj=E4l=E4?= <ville.syrjala@linux.intel.com>
To:     Kai-Heng Feng <kai.heng.feng@canonical.com>
Cc:     jani.nikula@linux.intel.com,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Uma Shankar <uma.shankar@intel.com>,
        Lucas De Marchi <lucas.demarchi@intel.com>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>,
        intel-gfx@lists.freedesktop.org,
        "open list:DRM DRIVERS" <dri-devel@lists.freedesktop.org>,
        open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] drm/i915/lspcon: Limits to 8 bpc for RGB/YCbCr444
Message-ID: <20200826162458.GP6112@intel.com>
References: <20200826052143.17607-1-kai.heng.feng@canonical.com>
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On Wed, Aug 26, 2020 at 01:21:15PM +0800, Kai-Heng Feng wrote:
> LSPCON only supports 8 bpc for RGB/YCbCr444.
> 
> Set the correct bpp otherwise it renders blank screen.

Hmm. Does 
git://github.com/vsyrjala/linux.git dp_downstream_ports_5
work?

Actually better make that dp_downstream_ports_5^^^^^^^^^^^ aka.
54d846ce62a2 ("drm/i915: Do YCbCr 444->420 conversion via DP protocol
converters") to avoid the experiments and hacks I have sitting on top.

> 
> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/2195
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> ---
>  drivers/gpu/drm/i915/display/intel_lspcon.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_lspcon.c b/drivers/gpu/drm/i915/display/intel_lspcon.c
> index b781bf469644..c7a44fcaade8 100644
> --- a/drivers/gpu/drm/i915/display/intel_lspcon.c
> +++ b/drivers/gpu/drm/i915/display/intel_lspcon.c
> @@ -196,7 +196,8 @@ void lspcon_ycbcr420_config(struct drm_connector *connector,
>  		crtc_state->port_clock /= 2;
>  		crtc_state->output_format = INTEL_OUTPUT_FORMAT_YCBCR444;
>  		crtc_state->lspcon_downsampling = true;
> -	}
> +	} else
> +		crtc_state->pipe_bpp = 24;
>  }
>  
>  static bool lspcon_probe(struct intel_lspcon *lspcon)
> -- 
> 2.17.1

-- 
Ville Syrj?l?
Intel