linux-kernel - Re: [PATCH RESEND 3/3] drm/bridge: it6505: skip auto training when previous try fail

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <ygndq6rndwduzxi77clpofvck4px5ohsnifpug6nupjzt4cs7g@npjx2othedpp>
Date: Sun, 23 Mar 2025 14:06:05 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Hermes Wu <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 RESEND 3/3] drm/bridge: it6505: skip auto training when
 previous try fail

On Tue, Mar 18, 2025 at 04:32:11PM +0800, Hermes Wu wrote:
> 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 | 36 +++++++++++++++++++++---------------
>  1 file changed, 21 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
> index 11231a642bbe185c4f36bf5f2a0b115fa056213b..730481a9446ff00a54ef70e86b4c28ff0a3f417e 100644
> --- a/drivers/gpu/drm/bridge/ite-it6505.c
> +++ b/drivers/gpu/drm/bridge/ite-it6505.c
> @@ -468,6 +468,7 @@ struct it6505 {
>  	struct work_struct hdcp_wait_ksv_list;
>  	struct completion extcon_completion;
>  	u8 auto_train_retry;
> +	u8 step_train_only;
>  	bool hdcp_desired;
>  	bool is_repeater;
>  	u8 hdcp_down_stream_count;
> @@ -2459,11 +2460,13 @@ 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);
>  }
> @@ -2479,21 +2482,23 @@ static void it6505_link_training_work(struct work_struct *work)
>  
>  	if (!it6505_get_sink_hpd_status(it6505))
>  		return;
> -
> -	retry = it6505->auto_train_retry;
> -	do {
> -		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, auto_train_retry: %d",
> -			     ret ? "pass" : "failed", it6505->auto_train_retry);
> -		if (ret) {
> -			it6505_link_train_ok(it6505);
> -			return;
> -		}
> -	} while (retry--);
> +	/* skip auto training if previous auto train is fail*/
> +	if (!it6505->step_train_only) {
> +		retry = it6505->auto_train_retry;
> +		do {
> +			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, auto_train_retry: %d",
> +				ret ? "pass" : "failed", it6505->auto_train_retry);
> +			if (ret) {
> +				it6505_link_train_ok(it6505);
> +				return;
> +			}
> +		} while (retry--);

This really looks like

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

Please consider changing the previous patch and this patch accordingly.

> +	}
>  
>  	/*After HW auto training fail, try link training step by step*/
>  	it6505_link_step_train_process(it6505);
> @@ -2605,6 +2610,7 @@ static void it6505_irq_hpd(struct it6505 *it6505)
>  			it6505_parse_link_capabilities(it6505);
>  		}
>  		it6505->auto_train_retry = AUTO_TRAIN_RETRY;
> +		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