linux-kernel - Re: [PATCH] drm/stm: ltdc: check crtc state before enabling LIE

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Date:   Thu, 23 Jan 2020 09:50:15 +0000
From:   Philippe CORNU <philippe.cornu@...com>
To:     Yannick FERTRE <yannick.fertre@...com>,
        Benjamin GAIGNARD <benjamin.gaignard@...com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        "Alexandre TORGUE" <alexandre.torgue@...com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-stm32@...md-mailman.stormreply.com" 
        <linux-stm32@...md-mailman.stormreply.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/stm: ltdc: check crtc state before enabling LIE

Dear Yannick,
Thank you for your patch,

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

Philippe :-)

On 1/21/20 11:14 AM, Yannick Fertre wrote:
> Following investigations of a hardware bug, the LIE interrupt
> can occur while the display controller is not activated.
> LIE interrupt (vblank) don't have to be set if the CRTC is not
> enabled.
> 
> Signed-off-by: Yannick Fertre <yannick.fertre@...com>
> ---
>   drivers/gpu/drm/stm/ltdc.c | 7 ++++++-
>   1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
> index c2815e8..ea654c7 100644
> --- a/drivers/gpu/drm/stm/ltdc.c
> +++ b/drivers/gpu/drm/stm/ltdc.c
> @@ -648,9 +648,14 @@ static const struct drm_crtc_helper_funcs ltdc_crtc_helper_funcs = {
>   static int ltdc_crtc_enable_vblank(struct drm_crtc *crtc)
>   {
>   	struct ltdc_device *ldev = crtc_to_ltdc(crtc);
> +	struct drm_crtc_state *state = crtc->state;
>   
>   	DRM_DEBUG_DRIVER("\n");
> -	reg_set(ldev->regs, LTDC_IER, IER_LIE);
> +
> +	if (state->enable)
> +		reg_set(ldev->regs, LTDC_IER, IER_LIE);
> +	else
> +		return -EPERM;
>   
>   	return 0;
>   }
>