From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 93C4EC433EF for ; Mon, 13 Dec 2021 12:45:16 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 8084A10E840; Mon, 13 Dec 2021 12:45:15 +0000 (UTC) Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by gabe.freedesktop.org (Postfix) with ESMTPS id DD75E10E827 for ; Mon, 13 Dec 2021 12:45:13 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10196"; a="238946793" X-IronPort-AV: E=Sophos;i="5.88,202,1635231600"; d="scan'208";a="238946793" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Dec 2021 04:45:13 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.88,202,1635231600"; d="scan'208";a="566574987" Received: from stinkbox.fi.intel.com (HELO stinkbox) ([10.237.72.171]) by fmsmga008.fm.intel.com with SMTP; 13 Dec 2021 04:45:11 -0800 Received: by stinkbox (sSMTP sendmail emulation); Mon, 13 Dec 2021 14:45:10 +0200 Date: Mon, 13 Dec 2021 14:45:10 +0200 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: "20211212153331.15457-1-shawn.c.lee@intel.com" <20211212153331.15457-1-shawn.c.lee@intel.com> Subject: Re: [PATCH] drm/edid: Refine HDMI VSDB detect Message-ID: References: <20211212153331.15457-1-shawn.c.lee@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Patchwork-Hint: comment X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Dave Airlie , "dri-devel@lists.freedesktop.org" Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Mon, Dec 13, 2021 at 12:42:22PM +0000, Lee, Shawn C wrote: > > On Monday, December 13, 2021 8:31 PM, Ville Syrjälä wrote: > >On Sun, Dec 12, 2021 at 11:33:31PM +0800, Lee Shawn C wrote: > >> According to CEA-861-F chapter 7.5.4. It says "The VSDB shall contain > >> the > >> 3 bytes of the IEEE OUI as well as any additional payload bytes needed." > >> Now DRM driver check HDMI OUI but VSDB payload size at least five bytes. > >> That may caused some HDMI monitors' audio feature can't be enabled. > >> Because of they only have three bytes payload (OUI only) in VSDB. > > > >HDMI 1.4a says > >"Sinks shall contain an HDMI VSDB minimally containing a 2-byte Source Physical Address field following the 24-bit identifier. ... > > The minimum value of N (length) is 5 and the maximum value of N is 31." > > > >Do you actually have an EDID that violates that? > > > > Yes! User report when connect to HDMI port on Acer V226HQL. Audio is not working. > But windows system did not have the same problem. We found its VSDB just have 3 bytes > payload (OUI). Then we share this patch to user then they report audio works properly > with this patch. Hrm. This deserves a comment then since it clearly violates the spec. Also a link to the bug if you have one would be nice to include here. > > Best regards, > Shawn > > >> > >> Cc: Ville Syrjälä > >> Cc: Adam Jackson > >> Cc: Dave Airlie > >> Signed-off-by: Lee Shawn C > >> --- > >> drivers/gpu/drm/drm_edid.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c > >> index 12893e7be89b..5aa4a6bf4a13 100644 > >> --- a/drivers/gpu/drm/drm_edid.c > >> +++ b/drivers/gpu/drm/drm_edid.c > >> @@ -4205,7 +4205,7 @@ static bool cea_db_is_hdmi_vsdb(const u8 *db) > >> if (cea_db_tag(db) != VENDOR_BLOCK) > >> return false; > >> > >> - if (cea_db_payload_len(db) < 5) > >> + if (cea_db_payload_len(db) < 3) > >> return false; > >> > >> return oui(db[3], db[2], db[1]) == HDMI_IEEE_OUI; > >> -- > >> 2.31.1 > > > >-- > >Ville Syrjälä > >Intel > > -- Ville Syrjälä Intel