From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga07.intel.com ([134.134.136.100]:14896 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752207AbdKHUp1 (ORCPT ); Wed, 8 Nov 2017 15:45:27 -0500 Date: Wed, 8 Nov 2017 22:45:23 +0200 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: Eric Anholt Cc: dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, stable@vger.kernel.org, Jani Nikula , Neil Kownacki Subject: Re: [PATCH] drm/edid: Don't send non-zero YQ in AVI infoframe for HDMI 1.x sinks Message-ID: <20171108204523.GJ10981@intel.com> References: <20171108152504.12596-1-ville.syrjala@linux.intel.com> <87k1z0bk4n.fsf@anholt.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <87k1z0bk4n.fsf@anholt.net> Sender: stable-owner@vger.kernel.org List-ID: On Wed, Nov 08, 2017 at 12:17:28PM -0800, Eric Anholt wrote: > Ville Syrjala writes: > > > From: Ville Syrj�l� > > > > Apparently some sinks look at the YQ bits even when receiving RGB, > > and they get somehow confused when they see a non-zero YQ value. > > So we can't just blindly follow CEA-861-F and set YQ to match the > > RGB range. > > > > Unfortunately there is no good way to tell whether the sink > > designer claims to have read CEA-861-F. The CEA extension block > > revision number has generally been stuck at 3 since forever, > > and even a very recently manufactured sink might be based on > > an old design so the manufacturing date doesn't seem like > > something we can use. In lieu of better information let's > > follow CEA-861-F only for HDMI 2.0 sinks, since HDMI 2.0 is > > based on CEA-861-F. For HDMI 1.x sinks we'll always set YQ=0. > > > > The alternative would of course be to always set YQ=0. And if > > we ever encounter a HDMI 2.0+ sink with this bug that's what > > we'll probably have to do. > > Should vc4 be doing anything special for HDMI2 sinks, if it's an HDMI1.4 > source? As long as you stick to < 340 MHz modes you shouldn't have to do anything. For >=340 MHz you'd need to use some new HDMI 2.0 features. Looks like vc4 crtc .mode_valid() doesn't do much. I presume it's up to bridges/encoders to filter out most things that aren't supported? > > That said, as far as vc4, this patch is > > Acked-by: Eric Anholt Ta. -- Ville Syrj�l� Intel OTC