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 X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 50D78C433DF for ; Fri, 9 Oct 2020 14:20:25 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 067782222F for ; Fri, 9 Oct 2020 14:20:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 067782222F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 6614C6ECE9; Fri, 9 Oct 2020 14:20:24 +0000 (UTC) Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by gabe.freedesktop.org (Postfix) with ESMTPS id 8519E6ECE9 for ; Fri, 9 Oct 2020 14:20:22 +0000 (UTC) IronPort-SDR: TsgcVzeJnEnS6QIDVwkUUgRf7HTNPhGVp93dqFAT1O5hYL2YpFvsSLY3NvvXJluKBbk5S/B2G4 jom6iED5m9sQ== X-IronPort-AV: E=McAfee;i="6000,8403,9768"; a="165603775" X-IronPort-AV: E=Sophos;i="5.77,355,1596524400"; d="scan'208";a="165603775" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Oct 2020 07:20:21 -0700 IronPort-SDR: KcKux4DIG6yCmiffyqjJ8vpqt/4Kx+nxtOGLpu3i+cAcZcX5qHFxeh+kGOeKtxw0GxlHjXw7ON rMy8oqFuCTaQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.77,355,1596524400"; d="scan'208";a="389154097" Received: from stinkbox.fi.intel.com (HELO stinkbox) ([10.237.72.174]) by orsmga001.jf.intel.com with SMTP; 09 Oct 2020 07:20:19 -0700 Received: by stinkbox (sSMTP sendmail emulation); Fri, 09 Oct 2020 17:20:18 +0300 Date: Fri, 9 Oct 2020 17:20:18 +0300 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: Pekka Paalanen Subject: Re: [PATCH] drm: document that user-space should avoid parsing EDIDs Message-ID: <20201009142018.GT6112@intel.com> References: <20201009131025.GS6112@intel.com> <20201009165651.31199071@eldfell> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20201009165651.31199071@eldfell> X-Patchwork-Hint: comment User-Agent: Mutt/1.10.1 (2018-07-13) 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: Daniel Vetter , dri-devel Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Fri, Oct 09, 2020 at 04:56:51PM +0300, Pekka Paalanen wrote: > On Fri, 9 Oct 2020 16:10:25 +0300 > Ville Syrj=E4l=E4 wrote: > = > > On Fri, Oct 09, 2020 at 01:07:20PM +0100, Daniel Stone wrote: > > > Hi, > > > = > > > On Fri, 9 Oct 2020 at 10:24, Simon Ser wrote: = > > > > User-space should avoid parsing EDIDs for metadata already exposed = via > > > > other KMS interfaces and properties. For instance, user-space shoul= d not > > > > try to extract a list of modes from the EDID: the kernel might muta= te > > > > the mode list (because of link capabilities or quirks for instance). > > > > > > > > Other metadata not exposed by KMS can be parsed by user-space. This > > > > includes for instance monitor identification (make/model/serial) and > > > > supported color-spaces. = > > > = > > > So I take it the only way to get modes is through the connector's list > > > of modes. That sounds reasonable enough to me, but I think to properly > > > handle colour (e.g. CEA modes have different behaviour for > > > limited/full range depending on which VIC they correspond to IIRC) = > > = > > If the mode has a VIC and that VIC is not 1, then it's limited range, > > otherwise full range. There are fortunately no cases where you would > > have the same exact timings corresponding to different quantization > > range depending on the VIC. > > = > > And the only reason the same timings could correspond to multiple VICs > > is aspect ratio. Which is already exposed via the mode flags, assuming > > the appropriate client cap is enabled. > > = > > So I think the only reason to expose the VIC would be if userspace is > > non-lazy and wants to manage its colors presicely, but is otherwise lazy > > and doesn't want to figure out what the VIC of the mode is on its own. > = > What would "figure out what the VIC of the mode is" require in userspace? > = > A database of all VIC modes and then compare if the detailed timings matc= h? > = > Is that also how the kernel recognises that userspace wants to set a > certain VIC mode instead of some arbitrary mode? Yes and yes. Note that atm we also don't have a way for userspace to say that it wants to signal limited range to the sink but wants the kernel to not do the full->limited range conversion. Ie. no way for userspace to pass in pixels that are already in limited range. There was a patch for that posted quite long ago, but it didn't go in. > = > Can CVT or GVT produce those exact timings? Can that accidentally > result in limited range? Not sure. -- = Ville Syrj=E4l=E4 Intel _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel