linux-kernel - Re: [PATCH 2/4] drm/panel: otm8009a: fix glitches by moving backlight enable to otm8009a

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Message-ID: <14a3dc6e-0a59-7c63-5195-95d6c1da7c54@st.com>
Date:   Mon, 14 May 2018 08:37:52 +0000
From:   Vincent ABRIOU <vincent.abriou@...com>
To:     Philippe CORNU <philippe.cornu@...com>,
        Thierry Reding <thierry.reding@...il.com>,
        David Airlie <airlied@...ux.ie>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Andrzej Hajda <a.hajda@...sung.com>,
        Yannick FERTRE <yannick.fertre@...com>,
        Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        Alexandre TORGUE <alexandre.torgue@...com>
Subject: Re: [PATCH 2/4] drm/panel: otm8009a: fix glitches by moving backlight
 enable to otm8009a_enable()

Hi Philippe,

Reviewed-by: Vincent Abriou <vincent.abriou@...com>

BR
Vincent

On 04/23/2018 04:10 PM, Philippe Cornu wrote:
> The backlight 1st update was in the otm8009a_prepare() function
> for a bad reason: backlight was not working in video mode and the
> otm8009a_prepare() is in command mode for the init sequence. As the
> backlight is now fixed (no lpm), it is good to put it back in the
> otm8009a_enable() function, avoiding also image glitches visible
> on some "slow" devices.
> 
> Signed-off-by: Philippe Cornu <philippe.cornu@...com>
> ---
>   drivers/gpu/drm/panel/panel-orisetech-otm8009a.c | 17 ++++++++++-------
>   1 file changed, 10 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panel/panel-orisetech-otm8009a.c b/drivers/gpu/drm/panel/panel-orisetech-otm8009a.c
> index 0fd2e0144d2b..de4a16d5275c 100644
> --- a/drivers/gpu/drm/panel/panel-orisetech-otm8009a.c
> +++ b/drivers/gpu/drm/panel/panel-orisetech-otm8009a.c
> @@ -330,13 +330,6 @@ static int otm8009a_prepare(struct drm_panel *panel)
>   
>   	ctx->prepared = true;
>   
> -	/*
> -	 * Power on the backlight. Note: end-user still controls brightness
> -	 * Note: ctx->prepared must be true before updating the backlight.
> -	 */
> -	ctx->bl_dev->props.power = FB_BLANK_UNBLANK;
> -	backlight_update_status(ctx->bl_dev);
> -
>   	return 0;
>   }
>   
> @@ -344,6 +337,16 @@ static int otm8009a_enable(struct drm_panel *panel)
>   {
>   	struct otm8009a *ctx = panel_to_otm8009a(panel);
>   
> +	if (ctx->enabled)
> +		return 0;
> +
> +	/*
> +	 * Power on the backlight. Note: end-user still controls brightness
> +	 * Note: ctx->prepared must be true before updating the backlight.
> +	 */
> +	ctx->bl_dev->props.power = FB_BLANK_UNBLANK;
> +	backlight_update_status(ctx->bl_dev);
> +
>   	ctx->enabled = true;
>   
>   	return 0;
>