linux-kernel - Re: [PATCH] drm/stm: ltdc: rework reset sequence

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Message-ID: <ff27f873-3d9b-373e-344d-6cd186cf384f@st.com>
Date:   Tue, 3 Jul 2018 11:02:38 +0000
From:   Philippe CORNU <philippe.cornu@...com>
To:     Yannick FERTRE <yannick.fertre@...com>,
        Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        Vincent ABRIOU <vincent.abriou@...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>
Subject: Re: [PATCH] drm/stm: ltdc: rework reset sequence

Hi Yannick,


On 06/29/2018 01:22 PM, Yannick Fertre wrote:
> Reset must be properly assert before deassert.
> This is important if there is an early boot splash screen
> before the kernel start up.
> 
> Signed-off-by: Yannick Fertre <yannick.fertre@...com>
> ---
>   drivers/gpu/drm/stm/ltdc.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
> index 96d20c2..8f4606d 100644
> --- a/drivers/gpu/drm/stm/ltdc.c
> +++ b/drivers/gpu/drm/stm/ltdc.c
> @@ -1130,8 +1130,11 @@ int ltdc_load(struct drm_device *ddev)
>   		}
>   	}
>   
> -	if (!IS_ERR(rstc))
> +	if (!IS_ERR(rstc)) {
> +		reset_control_assert(rstc);
> +		usleep_range(10, 20);
>   		reset_control_deassert(rstc);
> +	}

Thank you for your patch,

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

Philippe :-)

>   
>   	/* Disable interrupts */
>   	reg_clear(ldev->regs, LTDC_IER,
>