From mboxrd@z Thu Jan 1 00:00:00 1970 From: Damien Lespiau Subject: Re: [PATCH] drm/i915: Enable 5.4Ghz (HBR2) link rate for Displayport 1.2-capable devices Date: Fri, 17 Jan 2014 15:08:11 +0000 Message-ID: <20140117150810.GC20988@strange.amr.corp.intel.com> References: <1389927968-2473-1-git-send-email-tprevite@gmail.com> <52D94532.6020800@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by gabe.freedesktop.org (Postfix) with ESMTP id 4C3AE105A61 for ; Fri, 17 Jan 2014 07:13:13 -0800 (PST) Content-Disposition: inline In-Reply-To: <52D94532.6020800@gmail.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces@lists.freedesktop.org Errors-To: intel-gfx-bounces@lists.freedesktop.org To: Todd Previte Cc: intel-gfx List-Id: intel-gfx@lists.freedesktop.org On Fri, Jan 17, 2014 at 07:58:58AM -0700, Todd Previte wrote: > >>diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c > >>index 7df5085..f92d1c0 100644 > >>--- a/drivers/gpu/drm/i915/intel_dp.c > >>+++ b/drivers/gpu/drm/i915/intel_dp.c > >>@@ -102,7 +102,10 @@ intel_dp_max_link_bw(struct intel_dp *intel_dp) > >> case DP_LINK_BW_2_7: > >> break; > >> case DP_LINK_BW_5_4: /* 1.2 capable displays may advertise higher bw */ > >>- max_link_bw = DP_LINK_BW_2_7; > >>+ if (intel_dp->dpcd[DP_DPCD_REV] == 0x12) > >>+ max_link_bw = DP_LINK_BW_5_4; > >>+ else > >>+ max_link_bw = DP_LINK_BW_2_7; > >Is this really required, i.e. do we have dp 1.1 machines in the wild > >which advertise 5.4 but can't? In any case you also need to have a > >IS_HSW || IS_BDW check here, since only those two platforms support > >5.4 GHz. > I've not seen a case where a 1.1a capable device advertises HBR2, > no. I *have* seen the case where the sink reports that it only > supports RBR (1.62Ghz) but is in fact capable of 2.7Ghz. This is > more of a safety measure to eliminate potential training problems, > but is not strictly necessary to support HBR2. It does need the > IS_HSW || IS_BDW though, so I'll fix that and resend. Can we make it IS_HSW || INTEL_INFO(dev)->gen >= 8, we can't quite predict the future but new platforms supporting what old platforms do support is a bet we take elsewere. -- Damien