linux-kernel - Re: [PATCH v2 5/5] drm/bridge: it6505: skip auto training when previous try fail

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Message-ID: <poqcbsiibivd7sguf7pe477noo67jp2hfli54j5yeqgvzw7vdj@wmfjdqf6akmp>
Date: Sun, 30 Mar 2025 21:46:11 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Hermes.wu@....com.tw
Cc: Andrzej Hajda <andrzej.hajda@...el.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Robert Foss <rfoss@...nel.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        Pet.Weng@....com.tw, Kenneth.Hung@....com.tw, treapking@...omium.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 5/5] drm/bridge: it6505: skip auto training when
 previous try fail

On Wed, Mar 26, 2025 at 01:34:17PM +0800, Hermes Wu via B4 Relay wrote:
> From: Hermes Wu <Hermes.wu@....com.tw>
> 
> When connect to device which can only training done by
> step training, skip auto training when link training restart,
> usually happen when display resolution is changed.
> 
> Signed-off-by: Hermes Wu <Hermes.wu@....com.tw>
> ---
>  drivers/gpu/drm/bridge/ite-it6505.c | 29 +++++++++++++++++------------
>  1 file changed, 17 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
> index 2bbe787ccb1b57906f2a31a011dd92f327019b08..47f8134df8b6f5c2172c6cfdbc91da8063993a05 100644
> --- a/drivers/gpu/drm/bridge/ite-it6505.c
> +++ b/drivers/gpu/drm/bridge/ite-it6505.c
> @@ -467,6 +467,7 @@ struct it6505 {
>  	struct delayed_work hdcp_work;
>  	struct work_struct hdcp_wait_ksv_list;
>  	struct completion extcon_completion;
> +	u8 step_train_only;
>  	bool hdcp_desired;
>  	bool is_repeater;
>  	u8 hdcp_down_stream_count;
> @@ -2457,11 +2458,13 @@ static void it6505_link_step_train_process(struct it6505 *it6505)
>  				     ret ? "pass" : "failed", i + 1);
>  		if (ret) {
>  			it6505_link_train_ok(it6505);
> +			it6505->step_train_only = true;
>  			return;
>  		}
>  	}
>  
>  	DRM_DEV_DEBUG_DRIVER(dev, "training fail");
> +	it6505->step_train_only = false;
>  	it6505->link_state = LINK_IDLE;
>  	it6505_video_reset(it6505);
>  }
> @@ -2477,18 +2480,19 @@ static void it6505_link_training_work(struct work_struct *work)
>  
>  	if (!it6505_get_sink_hpd_status(it6505))
>  		return;
> -
> -	for (retry = AUTO_TRAIN_RETRY; retry > 0; retry--) {
> -		it6505_link_training_setup(it6505);
> -		it6505_reset_hdcp(it6505);
> -		it6505_aux_reset(it6505);
> -
> -		ret = it6505_link_start_auto_train(it6505);
> -		DRM_DEV_DEBUG_DRIVER(dev, "auto train %s,",
> -				     ret ? "pass" : "failed");
> -		if (ret) {
> -			it6505_link_train_ok(it6505);
> -			return;
> +	if (!it6505->step_train_only) {

No need to. Just

		for (retry = AUTO_TRAIN_RETRY; retry > 0 && !it6505->step_train_only; retry--) {

> +		for (retry = AUTO_TRAIN_RETRY; retry > 0; retry--) {
> +			it6505_link_training_setup(it6505);
> +			it6505_reset_hdcp(it6505);
> +			it6505_aux_reset(it6505);
> +
> +			ret = it6505_link_start_auto_train(it6505);
> +			DRM_DEV_DEBUG_DRIVER(dev, "auto train %s,",
> +					     ret ? "pass" : "failed");
> +			if (ret) {
> +				it6505_link_train_ok(it6505);
> +				return;
> +			}
>  		}
>  	}
>  
> @@ -2599,6 +2603,7 @@ static void it6505_irq_hpd(struct it6505 *it6505)
>  			it6505_variable_config(it6505);
>  			it6505_parse_link_capabilities(it6505);
>  		}
> +		it6505->step_train_only = false;
>  
>  		it6505_drm_dp_link_set_power(&it6505->aux, &it6505->link,
>  					     DP_SET_POWER_D0);
> 
> -- 
> 2.34.1
> 
> 

-- 
With best wishes
Dmitry