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 556CAC7EE32 for ; Thu, 26 Jun 2025 11:32:05 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id D629B10E89C; Thu, 26 Jun 2025 11:32:04 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="RPwL2HWk"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.16]) by gabe.freedesktop.org (Postfix) with ESMTPS id 6A82210E279; Thu, 26 Jun 2025 11:32:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1750937524; x=1782473524; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=gq/bMTMdynRkbjaoBXDaRsNLDVVDk/3ysvYQm1qny/M=; b=RPwL2HWkimY0nmn6NYuCRVPs0sfgCbivVo7Bk+ofyQDZnXTc12N6Yae3 S80IiwljWlawA8JG+Vxa1F7C9e9jJDk9v8DVotFBLWEZDxGTX4QxF+vkb AWL+WZ8k1NOHM2ZG8yLy2+ww67NkkZHc86SyY6c3O05jzBJ9SVzUtDh2q FKzGii1e4TmeHfRsrtl6DV9EgqOcx78HisJm0+ICjxICE/OjUGPc2xIXr t4X6wmsYmGDefZ6aOLyoqA2lVfEZ6UnluAsAJNg676rsZhoxg90ICYI0/ bv0pfUmsy4B91d4VloKJxZb5Y0IARjE8yV2GD14LDIwlgpz9usHvozJ/O g==; X-CSE-ConnectionGUID: +gLoQy5pTnaXjOlvs3deAA== X-CSE-MsgGUID: tG4QRk1URMKBnnRdoqiTDA== X-IronPort-AV: E=McAfee;i="6800,10657,11475"; a="53325190" X-IronPort-AV: E=Sophos;i="6.16,267,1744095600"; d="scan'208";a="53325190" Received: from orviesa005.jf.intel.com ([10.64.159.145]) by orvoesa108.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Jun 2025 04:32:04 -0700 X-CSE-ConnectionGUID: uBJcLQ18SIW8E+qm8oC9Sg== X-CSE-MsgGUID: CRrVo6QgRWasthqLibG25Q== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.16,267,1744095600"; d="scan'208";a="158251836" Received: from ijarvine-desk1.ger.corp.intel.com (HELO stinkbox) ([10.245.244.155]) by orviesa005.jf.intel.com with SMTP; 26 Jun 2025 04:32:01 -0700 Received: by stinkbox (sSMTP sendmail emulation); Thu, 26 Jun 2025 14:31:59 +0300 Date: Thu, 26 Jun 2025 14:31:59 +0300 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: Jani Nikula Cc: "Nautiyal, Ankit K" , intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org Subject: Re: [PATCH 1/2] Revert "drm/i915/dp: Reject HBR3 when sink doesn't support TPS4" Message-ID: References: <20250620124417.2041233-1-ankit.k.nautiyal@intel.com> <20250620124417.2041233-2-ankit.k.nautiyal@intel.com> <5fe0cd00-291b-4e93-a93a-6f8e32db4541@intel.com> <3d26024d8750cb1c188da77f7d3b07fb5b2cc40b@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <3d26024d8750cb1c188da77f7d3b07fb5b2cc40b@intel.com> X-Patchwork-Hint: comment X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" On Wed, Jun 25, 2025 at 11:18:03AM +0300, Jani Nikula wrote: > On Tue, 24 Jun 2025, Ville Syrjälä wrote: > > On Tue, Jun 24, 2025 at 10:10:53AM +0530, Nautiyal, Ankit K wrote: > >> > >> On 6/23/2025 8:12 PM, Ville Syrjälä wrote: > >> > On Fri, Jun 20, 2025 at 06:14:16PM +0530, Ankit Nautiyal wrote: > >> >> This reverts commit 584cf613c24a4250d9be4819efc841aa2624d5b6. > >> >> Commit 584cf613c24a ("drm/i915/dp: Reject HBR3 when sink doesn't support > >> >> TPS4") introduced a blanket rejection of HBR3 link rate when the sink does > >> >> not support TPS4. While this was intended to address instability observed > >> >> on certain eDP panels [1], the TPS4 requirement is only mandated for DPRX > >> >> and not for eDPRX. > >> > I see no exception given for eDP regarding this rule. The only exception > >> > allowed is that eDP can say DPCD_REV=1.4 + TPS4_SUPPORTED=0. So I still > >> > claim that these eDP sinks are violating the spec. > >> > >> Hmm.. Yes the spec allows eDP sinks to report DPCD_REV=1.4 and > >> TPS4_SUPPORTED, so perhaps eDPs claiming HBR3 with DPCD rev other than > >> rev 1.4 and not supporting TPS4 are indeed violating the spec. > >> > >> Would it make sense to add a condition that checks for DPCD_REV=1.4. > >> > >> Specifically: > >> > >> if DPCD_REV=1.4 and TPS4_SUPPORTED = 0, then do not prune the HBR3 rate? > >> > >> Or otherway if DPCD_REV!=1.4 and TPS4_SUPPORTER = 0, prune the HBR3 rate > >> > >> This way the patch need not be reverted, but modified to address > >> instability issues for eDP panels that are not aligned with the spec. > >> > >> That said, the gitlab issue#5969 [1] will still need another solution > >> since it seems to have DPCD rev 14 as per logs: > >> > >> DPCD: 14 1e 44 41 00 00 01 80 02 00 02 00 00 0b 80 > > > > I think we do need the quirk. But the commit message should IMO be > > adjusted so that it doesn't claim that these panels are 100% legal. > > Right. But are you okay with reverting 584cf613c24a ("drm/i915/dp: > Reject HBR3 when sink doesn't support TPS4") i.e. allowing HBR3 > *without* TPS4 by default, and quirking the panel that can't handle > HBR3? Yeah, I think the revert+quirk for the one known bad system is the way to go. > > No matter what the spec says, this seems to be common. More regressing > systems are cropping up, e.g. [1]. > > > BR, > Jani. > > > [1] https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14517 > > > > > -- > Jani Nikula, Intel -- Ville Syrjälä Intel