linux-kernel - Re: [PATCH] drm/bridge: adv7533: Reset DSI receiver logic

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Message-ID: <hukcjydehdbkk4xn3c62au4az4tlfjlkmxhq5db5xwabvxhyba@nf5tzddcbikv>
Date: Fri, 15 Nov 2024 10:10:56 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Stefan Ekenberg <stefan.ekenberg@...s.com>
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>, dri-devel@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org, kernel@...s.com
Subject: Re: [PATCH] drm/bridge: adv7533: Reset DSI receiver logic

On Wed, Nov 13, 2024 at 08:40:15AM +0100, Stefan Ekenberg wrote:
> Reset DSI receiver logic during power on. The need for this change was
> discovered when investigating issue with ADV7535. The symptom of the
> problem was that ADV7535 continuously outputs a black image. This
> happened for about 10% of the times that ADV7535 was powered on. The
> rest of the times the image was as expected.
> 
> The solution in this patch (placement of reset and sleep time of 200ms)
> is implemented as outlined by the Analog Devices support team.

Is this reset sequence specific only to adv7535? Is it applicable to
adv7533? adv7511?

> 
> Signed-off-by: Stefan Ekenberg <stefan.ekenberg@...s.com>
> ---
>  drivers/gpu/drm/bridge/adv7511/adv7533.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/gpu/drm/bridge/adv7511/adv7533.c b/drivers/gpu/drm/bridge/adv7511/adv7533.c
> index 4481489aaf5ebf164313c86cbf3447d2d7914ab9..93085c2b872ed98f4ee394236dc66c568c0e5ccf 100644
> --- a/drivers/gpu/drm/bridge/adv7511/adv7533.c
> +++ b/drivers/gpu/drm/bridge/adv7511/adv7533.c
> @@ -67,6 +67,15 @@ void adv7533_dsi_power_on(struct adv7511 *adv)
>  {
>  	struct mipi_dsi_device *dsi = adv->dsi;
>  
> +	/*
> +	 * Reset DSI receiver block logic to avoid ADV7535 startup problem.
> +	 * Without this reset it sometimes continuously fails to receive
> +	 * incoming DSI packets and outputs black image.
> +	 */
> +	regmap_write(adv->regmap_cec, 0x26, 0x18);
> +	msleep(200);
> +	regmap_write(adv->regmap_cec, 0x26, 0x38);
> +
>  	if (adv->use_timing_gen)
>  		adv7511_dsi_config_timing_gen(adv);
>  
> 
> ---
> base-commit: 59b723cd2adbac2a34fc8e12c74ae26ae45bf230
> change-id: 20241108-adv7533-dsi-reset-488c6fbb5e42
> 
> Best regards,
> -- 
> Stefan Ekenberg <stefan.ekenberg@...s.com>
> 

-- 
With best wishes
Dmitry