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Subject: Re: [PATCH] drm/i915/lspcon: Limits to 8 bpc for RGB/YCbCr444
From:   Kai Heng Feng <kai.heng.feng@canonical.com>
In-Reply-To: <20200826162458.GP6112@intel.com>
Date:   Thu, 27 Aug 2020 13:04:54 +0800
Cc:     Jani Nikula <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>
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References: <20200826052143.17607-1-kai.heng.feng@canonical.com>
 <20200826162458.GP6112@intel.com>
To:     =?utf-8?B?VmlsbGUgU3lyasOkbMOk?= <ville.syrjala@linux.intel.com>
Sender: linux-kernel-owner@vger.kernel.org
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Hi Ville,

> On Aug 27, 2020, at 12:24 AM, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> 
> 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.

Can you please rebase it to mainline master or drm-tip?

I am getting errors on the branch:

  DESCEND  objtool
  CALL    scripts/atomic/check-atomics.sh
  CALL    scripts/checksyscalls.sh
  CHK     include/generated/compile.h
  Building modules, stage 2.
  MODPOST 166 modules
  LD      arch/x86/boot/compressed/vmlinux
ld: arch/x86/boot/compressed/pgtable_64.o:(.bss+0x0): multiple definition of `__force_order'; arch/x86/boot/compressed/kaslr_64.o:(.bss+0x0): first defined here
ld: arch/x86/boot/compressed/head_64.o: warning: relocation in read-only section `.head.text'
ld: warning: creating DT_TEXTREL in a PIE
make[2]: *** [arch/x86/boot/compressed/Makefile:119: arch/x86/boot/compressed/vmlinux] Error 1
make[1]: *** [arch/x86/boot/Makefile:113: arch/x86/boot/compressed/vmlinux] Error 2
make: *** [arch/x86/Makefile:284: bzImage] Error 2
make: *** Waiting for unfinished jobs....

Kai-Heng

> 
>> 
>> 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 Syrjälä
> Intel