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@mediatek.com>
---
- Adjust DP training timing.
- Adjust parse capabilities timing.
- Add power on/off for connect/disconnect
---
 drivers/gpu/drm/mediatek/mtk_dp.c | 37 +++++++++++++++++--------------
 1 file changed, 20 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index ae4807823a5c..e87f6f52bcce 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -1873,6 +1873,7 @@ 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);
@@ -1891,9 +1892,28 @@ 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;
 		}
 	}
 
@@ -2060,16 +2080,6 @@ static const struct drm_edid *mtk_dp_edid_read(struct drm_bridge *bridge,
 
 	drm_edid = drm_edid_read_ddc(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");
-		drm_edid_free(drm_edid);
-		drm_edid = NULL;
-	}
-
 	if (drm_edid) {
 		/*
 		 * FIXME: get rid of drm_edid_raw()
@@ -2263,13 +2273,6 @@ static void mtk_dp_bridge_atomic_enable(struct drm_bridge *bridge,
 
 	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;
-	}
-
 	ret = mtk_dp_video_config(mtk_dp);
 	if (ret)
 		goto power_off_aux;
-- 
2.45.2

Hi, Liankun:

On Fri, 2024-10-25 at 16:28 +0800, Liankun Yang wrote:
> 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@mediatek.com>
> ---
> - Adjust DP training timing.
> - Adjust parse capabilities timing.
> - Add power on/off for connect/disconnect
> ---
>  drivers/gpu/drm/mediatek/mtk_dp.c | 37 +++++++++++++++++--------------
>  1 file changed, 20 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
> index ae4807823a5c..e87f6f52bcce 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dp.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dp.c
> @@ -1873,6 +1873,7 @@ 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);
> @@ -1891,9 +1892,28 @@ 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;

If 'mtk_dp->enabled = false' is directly associated to power off aux,
remove 'mtk_dp->enabled = false" in atomic disable.

> +			/* power off aux */
> +			mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
> +			       DP_PWR_STATE_BANDGAP_TPLL,
> +			       DP_PWR_STATE_MASK);

I know original atomic disable just power off aux, but why just power off aux not power off panel?

> +
>  			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;

You move part code in atomic_enable to here.
It seems that 'mtk_dp->enabled = true' is directly associated to mtk_dp_aux_panel_poweron(),
remove 'mtk_dp->enabled = true' in atomic enable.

Regards,
CK

>  		}
>  	}
>  
> @@ -2060,16 +2080,6 @@ static const struct drm_edid *mtk_dp_edid_read(struct drm_bridge *bridge,
>  
>  	drm_edid = drm_edid_read_ddc(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");
> -		drm_edid_free(drm_edid);
> -		drm_edid = NULL;
> -	}
> -
>  	if (drm_edid) {
>  		/*
>  		 * FIXME: get rid of drm_edid_raw()
> @@ -2263,13 +2273,6 @@ static void mtk_dp_bridge_atomic_enable(struct drm_bridge *bridge,
>  
>  	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;
> -	}
> -
>  	ret = mtk_dp_video_config(mtk_dp);
>  	if (ret)
>  		goto power_off_aux;