Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753141AbbG2PWp (ORCPT ); Wed, 29 Jul 2015 11:22:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53928 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751291AbbG2PWo (ORCPT ); Wed, 29 Jul 2015 11:22:44 -0400 Date: Wed, 29 Jul 2015 11:22:40 -0400 From: Benjamin Tissoires To: Sivakumar Thulasimani Cc: Daniel Vetter , intel-gfx@lists.freedesktop.org, Todd Broch , linux-kernel@vger.kernel.org Subject: Re: [Intel-gfx] [PATCH 3/3] drm/i915: Support DDI lane reversal for DP Message-ID: <20150729152240.GD2743@mail.corp.redhat.com> References: <1438099409-25456-1-git-send-email-benjamin.tissoires@redhat.com> <1438099409-25456-4-git-send-email-benjamin.tissoires@redhat.com> <55B88E25.6000006@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <55B88E25.6000006@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5365 Lines: 134 On Jul 29 2015 or thereabouts, Sivakumar Thulasimani wrote: > why not detect reverse in intel_dp_detect/intel_hpd_pulse ? that way you can > identify both lane count and reversal state without touching anything in the > link training code. i am yet to upstream my changes for CHT that i can share > if required that does the same in intel_dp_detect without touching any line > in link training path. With my current limited knowledge of the dp hotplug (and i915 driver) I am not sure we could detect the reversed state without trying to train 1 lane only. I'd be glad to look at your changes and test them on my system if you think that could help having a cleaner solution. Cheers, Benjamin > > On 7/28/2015 9:33 PM, Benjamin Tissoires wrote: > >The DP outputs connected through a USB Type-C port can have inverted > >lanes. To detect that case, we implement autodetection by training only > >the first lane if it doesn't work, we assume that we need to invert > >the lanes. > > > >Tested on a Chromebook Pixel 2015 (samus) with a USB Type-C to HDMI > >adapter and a Dell 4K and some various regular monitors. > > > >Based on 2 patches from the ChromeOS tree by: > >Stéphane Marchesin > >Todd Broch > > > >Signed-off-by: Benjamin Tissoires > >--- > > drivers/gpu/drm/i915/intel_ddi.c | 13 +++++++++++++ > > drivers/gpu/drm/i915/intel_dp.c | 36 ++++++++++++++++++++++++++++++++++++ > > drivers/gpu/drm/i915/intel_drv.h | 1 + > > 3 files changed, 50 insertions(+) > > > >diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c > >index 9a40bfb..0b0c1ec 100644 > >--- a/drivers/gpu/drm/i915/intel_ddi.c > >+++ b/drivers/gpu/drm/i915/intel_ddi.c > >@@ -2249,6 +2249,7 @@ static void intel_ddi_pre_enable(struct intel_encoder *intel_encoder) > > enum port port = intel_ddi_get_encoder_port(intel_encoder); > > int type = intel_encoder->type; > > int hdmi_level; > >+ bool reversed = false; > > if (type == INTEL_OUTPUT_EDP) { > > struct intel_dp *intel_dp = enc_to_intel_dp(encoder); > >@@ -2295,8 +2296,20 @@ static void intel_ddi_pre_enable(struct intel_encoder *intel_encoder) > > if (type == INTEL_OUTPUT_DISPLAYPORT || type == INTEL_OUTPUT_EDP) { > > struct intel_dp *intel_dp = enc_to_intel_dp(encoder); > >+ if (IS_BROADWELL(dev) && type == INTEL_OUTPUT_DISPLAYPORT) { > >+ intel_ddi_init_dp_buf_reg(intel_encoder); > >+ reversed = intel_dp_is_reversed(intel_dp); > >+ } > >+ > > intel_ddi_init_dp_buf_reg(intel_encoder); > >+ if (IS_BROADWELL(dev)) { > >+ if (reversed) > >+ intel_dp->DP |= DDI_BUF_PORT_REVERSAL; > >+ else > >+ intel_dp->DP &= ~DDI_BUF_PORT_REVERSAL; > >+ } > >+ > > intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON); > > intel_dp_start_link_train(intel_dp); > > intel_dp_complete_link_train(intel_dp); > >diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c > >index b740987..18280cc 100644 > >--- a/drivers/gpu/drm/i915/intel_dp.c > >+++ b/drivers/gpu/drm/i915/intel_dp.c > >@@ -3820,6 +3820,42 @@ intel_dp_complete_link_train(struct intel_dp *intel_dp) > > intel_dp->DP = DP; > > } > >+bool intel_dp_is_reversed(struct intel_dp *intel_dp) > >+{ > >+ struct drm_encoder *encoder = &dp_to_dig_port(intel_dp)->base.base; > >+ struct drm_device *dev = encoder->dev; > >+ struct drm_i915_private *dev_priv = dev->dev_private; > >+ uint32_t DP = intel_dp->DP; > >+ > >+ /* > >+ * Train with 1 lane. There is no guarantee that the monitor supports > >+ * 2 or 4 lanes, and we wouldn't see any asymetricity with 4 lanes. > >+ */ > >+ const uint8_t lane_count = 1; > >+ bool reversed; > >+ > >+ if (!HAS_DDI(dev)) > >+ return false; > >+ > >+ DP &= ~(DDI_BUF_PORT_REVERSAL | DDI_PORT_WIDTH(4)); > >+ DP |= DDI_PORT_WIDTH(lane_count); > >+ > >+ I915_WRITE(intel_dp->output_reg, DP); > >+ POSTING_READ(intel_dp->output_reg); > >+ udelay(600); > >+ > >+ if (!_intel_dp_start_link_train(intel_dp, lane_count, &DP, true)) > >+ return true; > >+ > >+ reversed = !_intel_dp_complete_link_train(intel_dp, lane_count, &DP, true); > >+ > >+ /* clear training, we had only one lane */ > >+ intel_dp->train_set_valid = false; > >+ > >+ return reversed; > >+ > >+} > >+ > > void intel_dp_stop_link_train(struct intel_dp *intel_dp) > > { > > intel_dp_set_link_train(intel_dp, &intel_dp->DP, > >diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h > >index 320c9e6..cba00c6 100644 > >--- a/drivers/gpu/drm/i915/intel_drv.h > >+++ b/drivers/gpu/drm/i915/intel_drv.h > >@@ -1169,6 +1169,7 @@ int intel_dp_sink_crc(struct intel_dp *intel_dp, u8 *crc); > > bool intel_dp_compute_config(struct intel_encoder *encoder, > > struct intel_crtc_state *pipe_config); > > bool intel_dp_is_edp(struct drm_device *dev, enum port port); > >+bool intel_dp_is_reversed(struct intel_dp *intel_dp); > > enum irqreturn intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, > > bool long_hpd); > > void intel_edp_backlight_on(struct intel_dp *intel_dp); > > -- > regards, > Sivakumar > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/