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 59C30C54EED for ; Thu, 26 Jan 2023 15:09:48 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 796E610E151; Thu, 26 Jan 2023 15:09:44 +0000 (UTC) Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by gabe.freedesktop.org (Postfix) with ESMTPS id 9389110E137; Thu, 26 Jan 2023 15:09:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1674745782; x=1706281782; h=from:to:cc:subject:in-reply-to:references:date: message-id:mime-version; bh=3Q710a4bqKm8pegZyHRFEOiSZ9RbPCWOZqnH7KZaWgc=; b=S98T6GVLM79oB0fNF6IQMMDQg7xuEENJc2EBeSFopmYT59oMLSOUwxrw Iab+53ZR5t2jRZq3wftqlx/3cHtmgrfB8XiAq4/29ZdhHqsAns/tPGZLh nCe+t4hlk+5G2VVWmLy9tlupATfe0FnWtVXVEbZIcH2nOLeRNnM7gcfr7 QgkUANGK7+tuSOYRvOFRRXCWIwos5BqZujXMuAhhQD01Mor9SIxINFglm GfuP/f0aEH+gap9JZhb/fKF4hYyxp0Cp4VuJW/yeAnistwT3bbN7zpbp4 hDb+vWb9zntUF/931MdZX/zEjb1Tp9+oLSWyAT3N/scKOQgarqfE6iWjw A==; X-IronPort-AV: E=McAfee;i="6500,9779,10602"; a="328099508" X-IronPort-AV: E=Sophos;i="5.97,248,1669104000"; d="scan'208";a="328099508" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Jan 2023 07:00:19 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10602"; a="771164157" X-IronPort-AV: E=Sophos;i="5.97,248,1669104000"; d="scan'208";a="771164157" Received: from jnikula-mobl4.fi.intel.com (HELO localhost) ([10.237.66.157]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Jan 2023 07:00:17 -0800 From: Jani Nikula To: Arun R Murthy , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org In-Reply-To: <20230120061600.1451088-3-arun.r.murthy@intel.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: <20230120061600.1451088-1-arun.r.murthy@intel.com> <20230120061600.1451088-3-arun.r.murthy@intel.com> Date: Thu, 26 Jan 2023 17:00:14 +0200 Message-ID: <875yct5ojl.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Intel-gfx] [RESEND PATCHv2 2/2] i915/display/dp: SDP CRC16 for 128b132b link layer X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Fri, 20 Jan 2023, Arun R Murthy wrote: > Enable SDP error detection configuration, this will set CRC16 in > 128b/132b link layer. > For Display version 13 a hardware bit31 in register VIDEO_DIP_CTL is > added to enable/disable SDP CRC applicable for DP2.0 only, but the > default value of this bit will enable CRC16 in 128b/132b hence > skipping this write. > Corrective actions on SDP corruption is yet to be defined. > > v2: Moved the CRC enable to link training init(Jani N) Yeah, well, I said where this doesn't belong, and I don't think it really belongs here either. :( It has nothing to do with link training or intel_dp_start_link_train(). Alas, I'm not really sure what the right place is, I just know this isn't it. The specs don't give us any clues. The DP specs says absolutely nothing about when this could or should be written. *Maybe* in intel_ddi_pre_enable() or intel_mst_pre_enable_dp()? Before sending any SDPs. BR, Jani. > > Signed-off-by: Arun R Murthy > --- > .../gpu/drm/i915/display/intel_dp_link_training.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c b/drivers/gpu/drm/i915/display/intel_dp_link_training.c > index 3d3efcf02011..7064e465423b 100644 > --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c > +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c > @@ -1453,4 +1453,16 @@ void intel_dp_start_link_train(struct intel_dp *intel_dp, > > if (!passed) > intel_dp_schedule_fallback_link_training(intel_dp, crtc_state); > + > + /* DP v2.0 SCR on SDP CRC16 for 128b/132b Link Layer */ > + if (intel_dp_is_uhbr(crtc_state) && passed) > + drm_dp_dpcd_writeb(&intel_dp->aux, > + DP_SDP_ERROR_DETECTION_CONFIGURATION, > + DP_SDP_CRC16_128B132B_EN); > + /* > + * VIDEO_DIP_CTL register bit 31 should be set to '0' to not > + * disable SDP CRC. This is applicable for Display version 13. > + * Default value of bit 31 is '0' hence discarding the write > + */ > + /* TODO: Corrective actions on SDP corruption yet to be defined */ > } -- Jani Nikula, Intel Open Source Graphics Center