linux-kernel - [PATCH v1 1/1] drm/mediatek/ dp: Adjust bandwidth limit for DP

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Message-ID: <20240315015233.2023-1-liankun.yang@mediatek.com>
Date: Fri, 15 Mar 2024 09:52:26 +0800
From: Liankun Yang <liankun.yang@...iatek.com>
To: <chunkuang.hu@...nel.org>, <p.zabel@...gutronix.de>, <airlied@...il.com>,
	<daniel@...ll.ch>, <matthias.bgg@...il.com>,
	<angelogioacchino.delregno@...labora.com>, <jitao.shi@...iatek.com>,
	<mac.shen@...iatek.com>, <liankun.yang@...iatek.com>
CC: <dri-devel@...ts.freedesktop.org>, <linux-mediatek@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>
Subject: [PATCH v1 1/1] drm/mediatek/ dp: Adjust bandwidth limit for DP

By adjusting the order of link training and relocating it to HPD,
link training can identify the usability of each lane in the current link.

It also supports handling signal instability and weakness due to
environmental issues, enabling the acquisition of a stable bandwidth
for the current link. Subsequently, DP work can proceed based on
the actual maximum bandwidth.

It should training in the hpd event thread.
Check the mode with lane count and link rate of training.

Signed-off-by: Liankun Yang <liankun.yang@...iatek.com>
---
 drivers/gpu/drm/mediatek/mtk_dp.c | 57 +++++++++++++++----------------
 1 file changed, 28 insertions(+), 29 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index 2136a596efa1..14da6077f947 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -1870,6 +1870,7 @@ static irqreturn_t mtk_dp_hpd_event_thread(int hpd, void *dev)
 	struct mtk_dp *mtk_dp = dev;
 	unsigned long flags;
 	u32 status;
+	int ret;
 
 	if (mtk_dp->need_debounce && mtk_dp->train_info.cable_plugged_in)
 		msleep(100);
@@ -1888,9 +1889,28 @@ static irqreturn_t mtk_dp_hpd_event_thread(int hpd, void *dev)
 			memset(&mtk_dp->info.audio_cur_cfg, 0,
 			       sizeof(mtk_dp->info.audio_cur_cfg));
 
+			mtk_dp->enabled = false;
+			/* power off aux */
+			mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
+			       DP_PWR_STATE_BANDGAP_TPLL,
+			       DP_PWR_STATE_MASK);
+
 			mtk_dp->need_debounce = false;
 			mod_timer(&mtk_dp->debounce_timer,
 				  jiffies + msecs_to_jiffies(100) - 1);
+		} else {
+			mtk_dp_aux_panel_poweron(mtk_dp, true);
+
+			ret = mtk_dp_parse_capabilities(mtk_dp);
+			if (ret)
+				drm_err(mtk_dp->drm_dev, "Can't parse capabilities\n");
+
+			/* Training */
+			ret = mtk_dp_training(mtk_dp);
+			if (ret)
+				drm_err(mtk_dp->drm_dev, "Training failed, %d\n", ret);
+
+			mtk_dp->enabled = true;
 		}
 	}
 
@@ -2057,16 +2077,6 @@ static struct edid *mtk_dp_get_edid(struct drm_bridge *bridge,
 
 	new_edid = drm_get_edid(connector, &mtk_dp->aux.ddc);
 
-	/*
-	 * Parse capability here to let atomic_get_input_bus_fmts and
-	 * mode_valid use the capability to calculate sink bitrates.
-	 */
-	if (mtk_dp_parse_capabilities(mtk_dp)) {
-		drm_err(mtk_dp->drm_dev, "Can't parse capabilities\n");
-		kfree(new_edid);
-		new_edid = NULL;
-	}
-
 	if (new_edid) {
 		struct cea_sad *sads;
 
@@ -2243,14 +2253,10 @@ static void mtk_dp_bridge_atomic_enable(struct drm_bridge *bridge,
 		return;
 	}
 
-	mtk_dp_aux_panel_poweron(mtk_dp, true);
-
-	/* Training */
-	ret = mtk_dp_training(mtk_dp);
-	if (ret) {
-		drm_err(mtk_dp->drm_dev, "Training failed, %d\n", ret);
-		goto power_off_aux;
-	}
+	/* power on aux */
+	mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
+			   DP_PWR_STATE_BANDGAP_TPLL_LANE,
+			   DP_PWR_STATE_MASK);
 
 	ret = mtk_dp_video_config(mtk_dp);
 	if (ret)
@@ -2269,7 +2275,6 @@ static void mtk_dp_bridge_atomic_enable(struct drm_bridge *bridge,
 		       sizeof(mtk_dp->info.audio_cur_cfg));
 	}
 
-	mtk_dp->enabled = true;
 	mtk_dp_update_plugged_status(mtk_dp);
 
 	return;
@@ -2284,16 +2289,10 @@ static void mtk_dp_bridge_atomic_disable(struct drm_bridge *bridge,
 {
 	struct mtk_dp *mtk_dp = mtk_dp_from_bridge(bridge);
 
-	mtk_dp->enabled = false;
 	mtk_dp_update_plugged_status(mtk_dp);
 	mtk_dp_video_enable(mtk_dp, false);
 	mtk_dp_audio_mute(mtk_dp, true);
 
-	if (mtk_dp->train_info.cable_plugged_in) {
-		drm_dp_dpcd_writeb(&mtk_dp->aux, DP_SET_POWER, DP_SET_POWER_D3);
-		usleep_range(2000, 3000);
-	}
-
 	/* power off aux */
 	mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
 			   DP_PWR_STATE_BANDGAP_TPLL,
@@ -2310,10 +2309,10 @@ mtk_dp_bridge_mode_valid(struct drm_bridge *bridge,
 {
 	struct mtk_dp *mtk_dp = mtk_dp_from_bridge(bridge);
 	u32 bpp = info->color_formats & DRM_COLOR_FORMAT_YCBCR422 ? 16 : 24;
-	u32 rate = min_t(u32, drm_dp_max_link_rate(mtk_dp->rx_cap) *
-			      drm_dp_max_lane_count(mtk_dp->rx_cap),
-			 drm_dp_bw_code_to_link_rate(mtk_dp->max_linkrate) *
-			 mtk_dp->max_lanes);
+
+	u32 lane_count_min = mtk_dp->train_info.lane_count;
+	u32 rate = drm_dp_bw_code_to_link_rate(mtk_dp->train_info.link_rate) *
+			 lane_count_min;
 
 	if (rate < mode->clock * bpp / 8)
 		return MODE_CLOCK_HIGH;
-- 
2.43.0