linux-kernel - Re: [PATCH] drm/panel: otm8009a: add delay at the end of initialization

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Message-ID: <f027e4d6-7a49-8e1d-c019-e244b2bbc7e6@st.com>
Date:   Tue, 26 Mar 2019 12:48:24 +0000
From:   Philippe CORNU <philippe.cornu@...com>
To:     Yannick FERTRE <yannick.fertre@...com>,
        Thierry Reding <thierry.reding@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-stm32@...md-mailman.stormreply.com" 
        <linux-stm32@...md-mailman.stormreply.com>
Subject: Re: [PATCH] drm/panel: otm8009a: add delay at the end of
 initialization

Dear Yannick,
Many thanks for your patch.

Reviewed-by: Philippe Cornu <philippe.cornu@...com>
Tested-by: Philippe Cornu <philippe.cornu@...com>

Best regards,
Philippe

On 3/21/19 9:04 AM, Yannick Fertré wrote:
> At the end of initialization, a delay is required by the panel.
> Without this delay, the panel could received a frame early &
> generate a crash of panel (black screen).
> 
> Signed-off-by: Yannick Fertré <yannick.fertre@...com>
> ---
>   drivers/gpu/drm/panel/panel-orisetech-otm8009a.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/panel/panel-orisetech-otm8009a.c b/drivers/gpu/drm/panel/panel-orisetech-otm8009a.c
> index 87fa316..58ccf64 100644
> --- a/drivers/gpu/drm/panel/panel-orisetech-otm8009a.c
> +++ b/drivers/gpu/drm/panel/panel-orisetech-otm8009a.c
> @@ -248,6 +248,9 @@ static int otm8009a_init_sequence(struct otm8009a *ctx)
>   	/* Send Command GRAM memory write (no parameters) */
>   	dcs_write_seq(ctx, MIPI_DCS_WRITE_MEMORY_START);
>   
> +	/* Wait a short while to let the panel be ready before the 1st frame */
> +	mdelay(10);
> +
>   	return 0;
>   }
>   
>