linux-kernel - Re: [PATCH RESEND 2/3] drm/bridge: it6505: modify DP link training work

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <7ltrwnweqk4dvqicppdpsj7pcbvky5peiwrunnfyvacklwuqia@265ovn3v3ifw>
Date: Sun, 23 Mar 2025 14:04:22 +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 2/3] drm/bridge: it6505: modify DP link training
 work

On Tue, Mar 18, 2025 at 04:32:10PM +0800, Hermes Wu wrote:
> The DP link training work include auto training and after
> auto training failed "auto_train_retry" times, it switch to
> step training mode.
> 
> It will more efficiency that finish link auto training,
> include retry, and step training in a work, rather than
> re-schedule train work when each training fail.
> 
> it6505_dump() is remove from link trainig work, it takes too much
> time to read all register area, and is not necessary.
> 
> Signed-off-by: Hermes Wu <Hermes.wu@....com.tw>
> ---
>  drivers/gpu/drm/bridge/ite-it6505.c | 35 ++++++++++++++++-------------------
>  1 file changed, 16 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
> index dc1179c8338e27866f6adda4ef8fb2950336221b..11231a642bbe185c4f36bf5f2a0b115fa056213b 100644
> --- a/drivers/gpu/drm/bridge/ite-it6505.c
> +++ b/drivers/gpu/drm/bridge/ite-it6505.c
> @@ -666,7 +666,7 @@ static int it6505_get_dpcd(struct it6505 *it6505, int offset, u8 *dpcd, int num)
>  	return 0;
>  }
>  
> -static void it6505_dump(struct it6505 *it6505)
> +static void __maybe_unused it6505_dump(struct it6505 *it6505)
>  {
>  	unsigned int i, j;
>  	u8 regs[16];
> @@ -2472,7 +2472,7 @@ static void it6505_link_training_work(struct work_struct *work)
>  {
>  	struct it6505 *it6505 = container_of(work, struct it6505, link_works);
>  	struct device *dev = it6505->dev;
> -	int ret;
> +	int ret, retry;
>  
>  	DRM_DEV_DEBUG_DRIVER(dev, "it6505->sink_count: %d",
>  			     it6505->sink_count);
> @@ -2480,26 +2480,23 @@ static void it6505_link_training_work(struct work_struct *work)
>  	if (!it6505_get_sink_hpd_status(it6505))
>  		return;
>  
> -	it6505_link_training_setup(it6505);
> -	it6505_reset_hdcp(it6505);
> -	it6505_aux_reset(it6505);
> -
> -	if (it6505->auto_train_retry < 1) {
> -		it6505_link_step_train_process(it6505);
> -		return;
> -	}
> +	retry = it6505->auto_train_retry;

Should you also drop auto_train_retry from the structure and assign
AUTO_TRAIN_RETRY here instead?

> +	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 = 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--);
>  
> -	if (ret) {
> -		it6505->auto_train_retry = AUTO_TRAIN_RETRY;
> -		it6505_link_train_ok(it6505);
> -	} else {
> -		it6505->auto_train_retry--;
> -		it6505_dump(it6505);
> -	}
> +	/*After HW auto training fail, try link training step by step*/
> +	it6505_link_step_train_process(it6505);
>  
>  }
>  
> 
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry