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From:   Jani Nikula <jani.nikula@linux.intel.com>
To:     Kai-Heng Feng <kai.heng.feng@canonical.com>, airlied@linux.ie
Cc:     linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
        Kai-Heng Feng <kai.heng.feng@canonical.com>,
        daniel.vetter@intel.com
Subject: Re: [PATCH] drm/edid: Add 6 bpc quirk for CPT panel in Asus UX303LA
In-Reply-To: <20180218085359.7817-1-kai.heng.feng@canonical.com>
Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo
References: <20180218085359.7817-1-kai.heng.feng@canonical.com>
Date:   Mon, 19 Feb 2018 12:42:52 +0200
Message-ID: <87woz99s5v.fsf@intel.com>
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Content-Type: text/plain
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Sun, 18 Feb 2018, Kai-Heng Feng <kai.heng.feng@canonical.com> wrote:
> Similar to commit e10aec652f31 ("drm/edid: Add 6 bpc quirk for display
> AEO model 0."), the EDID reports "DFP 1.x compliant TMDS" but it support
> 6bpc instead of 8 bpc.
>
> Hence, use 6 bpc quirk for this panel.
>
> Fixes: 196f954e2509 ("drm/i915/dp: Revert "drm/i915/dp: fall back to 18 bpp when sink capability is unknown"")

Implies

Cc: <stable@vger.kernel.org> # v4.8+

> BugLink: https://bugs.launchpad.net/bugs/1749420
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> ---
>  drivers/gpu/drm/drm_edid.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index ddd537914575..d9c8d718e261 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -113,6 +113,9 @@ static const struct edid_quirk {
>  	/* AEO model 0 reports 8 bpc, but is a 6 bpc panel */
>  	{ "AEO", 0, EDID_QUIRK_FORCE_6BPC },
>  
> +	/* CPT panel of Asus UX303LA reports 8 bpc, but is a 6 bpc panel */
> +	{ "CPT", 0x17df, EDID_QUIRK_FORCE_6BPC },
> +
>  	/* Belinea 10 15 55 */
>  	{ "MAX", 1516, EDID_QUIRK_PREFER_LARGE_60 },
>  	{ "MAX", 0x77e, EDID_QUIRK_PREFER_LARGE_60 },

-- 
Jani Nikula, Intel Open Source Technology Center