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From: Uma Shankar <uma.shankar@intel.com>
To: intel-gfx@lists.freedesktop.org
Subject: [v1 6/6] drm/i915/display: Reduce blanking to support 4k60@10bpp for LSPCON
Date: Wed, 16 Oct 2019 16:02:49 +0530	[thread overview]
Message-ID: <20191016103249.32121-7-uma.shankar@intel.com> (raw)
In-Reply-To: <20191016103249.32121-1-uma.shankar@intel.com>

Blanking needs to be reduced to incorporate DP and HDMI timing/link
bandwidth limitations for CEA modes (4k@60 at 10 bpp). DP can drive
17.28Gbs while 4k modes (VIC97 etc) at 10 bpp required 17.8 Gbps.
This will cause mode to blank out. Reduced Htotal by shortening the
back porch and front porch within permissible limits.

Signed-off-by: Uma Shankar <uma.shankar@intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index d92777bd3bed..a12b6916023d 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -597,8 +597,10 @@ intel_dp_mode_valid(struct drm_connector *connector,
 {
 	struct intel_dp *intel_dp = intel_attached_dp(connector);
 	struct intel_connector *intel_connector = to_intel_connector(connector);
+	struct intel_encoder *intel_encoder = intel_attached_encoder(connector);
 	struct drm_display_mode *fixed_mode = intel_connector->panel.fixed_mode;
 	struct drm_i915_private *dev_priv = to_i915(connector->dev);
+	struct intel_lspcon *lspcon = enc_to_intel_lspcon(&intel_encoder->base);
 	int target_clock = mode->clock;
 	int max_rate, mode_rate, max_lanes, max_link_clock;
 	int max_dotclk;
@@ -620,6 +622,21 @@ intel_dp_mode_valid(struct drm_connector *connector,
 		target_clock = fixed_mode->clock;
 	}
 
+	/*
+	 * Reducing Blanking to incorporate DP and HDMI timing/link bandwidth
+	 * limitations for CEA modes (4k@60 at 10 bpp). DP can drive 17.28Gbs
+	 * while 4k modes (VIC97 etc) at 10 bpp required 17.8 Gbps. This will
+	 * cause mode to blank out. Reduced Htotal by shortening the back porch
+	 * and front porch within permissible limits.
+	 */
+	if (lspcon->active && lspcon->hdr_supported &&
+	    mode->clock > 570000) {
+		mode->clock = 570000;
+		mode->htotal -= 180;
+		mode->hsync_start -= 72;
+		mode->hsync_end -= 72;
+	}
+
 	max_link_clock = intel_dp_max_link_rate(intel_dp);
 	max_lanes = intel_dp_max_lane_count(intel_dp);
 
-- 
2.22.0

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  parent reply	other threads:[~2019-10-16 10:03 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-16 10:32 [v1 0/6] Enable HDR on MCA LSPCON based Gen9 devices Uma Shankar
2019-10-16 10:32 ` [v1 1/6] drm/i915/display: Add HDR Capability detection for LSPCON Uma Shankar
2019-10-16 10:32 ` [v1 2/6] drm/i915/display: Enable HDR on gen9 devices with MCA Lspcon Uma Shankar
2019-10-16 13:14   ` Ville Syrjälä
2019-10-16 14:16     ` Shankar, Uma
2019-10-16 10:32 ` [v1 3/6] drm/i915/display: Attach HDR property for capable Gen9 devices Uma Shankar
2019-10-16 10:32 ` [v1 4/6] drm/i915/display: Set HDR Infoframe for HDR capable LSPCON devices Uma Shankar
2019-10-16 10:32 ` [v1 5/6] drm/i915/display: Enable BT2020 for HDR on " Uma Shankar
2019-10-16 10:32 ` Uma Shankar [this message]
2019-10-16 13:13   ` [v1 6/6] drm/i915/display: Reduce blanking to support 4k60@10bpp for LSPCON Ville Syrjälä
2019-10-16 13:46     ` Shankar, Uma
2019-10-16 13:56       ` Ville Syrjälä
2019-10-16 14:13         ` Shankar, Uma
2019-10-16 12:31 ` ✗ Fi.CI.BUILD: failure for Enable HDR on MCA LSPCON based Gen9 devices Patchwork
2019-10-16 13:17 ` [v1 0/6] " Ville Syrjälä
2019-10-16 14:21   ` Shankar, Uma

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