From 6f317cfe42c9d8a7c9c1a327d2f1bcc517a3cd91 Mon Sep 17 00:00:00 2001 From: Lukas Wunner Date: Sun, 12 Apr 2015 21:10:35 +0200 Subject: [PATCH] drm/i915: Assume dual channel LVDS if pixel clock necessitates it MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Single channel LVDS maxes out at 112 MHz, anything above must be dual channel. This avoids the need to specify i915.lvds_channel_mode=2 on all 17" MacBook Pro models with i915 graphics since they had 1920x1200 (193 MHz), plus those 15" pre-retina models which had a resolution of 1680x1050 (119 MHz) as a BTO option. Source for 112 MHz limit of single channel LVDS is section 2.3 of: https://01.org/linuxgraphics/sites/default/files/documentation/ivb_ihd_os_vol3_part4.pdf v2: Avoid hardcoding 17" models by assuming dual channel LVDS if the resolution necessitates it, suggested by Jani Nikula. v3: Fix typo, thanks Joonas Lahtinen. v4: Split commit in two, suggested by Ville Syrjälä. Signed-off-by: Lukas Wunner Tested-by: Lukas Wunner Reviewed-by: Ville Syrjälä Cc: stable@vger.kernel.org [Jani: included spec reference into the commit message] Signed-off-by: Jani Nikula --- drivers/gpu/drm/i915/intel_lvds.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c index 5abda1d2c018..ee621e335d04 100644 --- a/drivers/gpu/drm/i915/intel_lvds.c +++ b/drivers/gpu/drm/i915/intel_lvds.c @@ -848,6 +848,11 @@ static bool compute_is_dual_link_lvds(struct intel_lvds_encoder *lvds_encoder) if (i915.lvds_channel_mode > 0) return i915.lvds_channel_mode == 2; + /* single channel LVDS is limited to 112 MHz */ + if (lvds_encoder->attached_connector->base.panel.fixed_mode->clock + > 112999) + return true; + if (dmi_check_system(intel_dual_link_lvds)) return true; @@ -1111,6 +1116,8 @@ void intel_lvds_init(struct drm_device *dev) out: mutex_unlock(&dev->mode_config.mutex); + intel_panel_init(&intel_connector->panel, fixed_mode, downclock_mode); + lvds_encoder->is_dual_link = compute_is_dual_link_lvds(lvds_encoder); DRM_DEBUG_KMS("detected %s-link lvds configuration\n", lvds_encoder->is_dual_link ? "dual" : "single"); @@ -1125,7 +1132,6 @@ out: } drm_connector_register(connector); - intel_panel_init(&intel_connector->panel, fixed_mode, downclock_mode); intel_panel_setup_backlight(connector, INVALID_PIPE); return; -- 2.20.1