linux-kernel - Re: [PATCH v4 1/4] drm/ingenic : add ingenic_drm_bridge_atomic

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Message-Id: <WF3R8R.TU622OO0WUTK3@crapouillou.net>
Date:   Mon, 14 Mar 2022 19:57:32 +0000
From:   Paul Cercueil <paul@...pouillou.net>
To:     Christophe Branchereau <cbranchereau@...il.com>
Cc:     David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>,
        Thierry Reding <thierry.reding@...il.com>,
        Sam Ravnborg <sam@...nborg.org>,
        Rob Herring <robh+dt@...nel.org>, linux-kernel@...r.kernel.org,
        linux-mips@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v4 1/4] drm/ingenic : add ingenic_drm_bridge_atomic_enable

Hi Christophe,

Le ven., mars 11 2022 at 18:02:37 +0100, Christophe Branchereau 
<cbranchereau@...il.com> a écrit :
> This allows the CRTC to be enabled after panels have slept out,
> and before their display is turned on, solving a graphical bug
> on the newvision nv3502c
> 
> Signed-off-by: Christophe Branchereau <cbranchereau@...il.com>
> ---
>  drivers/gpu/drm/ingenic/ingenic-drm-drv.c | 19 +++++++++++++------
>  1 file changed, 13 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c 
> b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> index dcf44cb00821..51512f41263e 100644
> --- a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> +++ b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
> @@ -226,6 +226,18 @@ static int ingenic_drm_update_pixclk(struct 
> notifier_block *nb,
>  	}
>  }
> 
> +static void ingenic_drm_bridge_atomic_enable(struct drm_bridge 
> *bridge,
> +					     struct drm_bridge_state *old_bridge_state)
> +{
> +	struct ingenic_drm *priv = drm_device_get_priv(bridge->dev);
> +
> +	regmap_write(priv->map, JZ_REG_LCD_STATE, 0);
> +
> +	regmap_update_bits(priv->map, JZ_REG_LCD_CTRL,
> +			   JZ_LCD_CTRL_ENABLE | JZ_LCD_CTRL_DISABLE,
> +			   JZ_LCD_CTRL_ENABLE);
> +}
> +
>  static void ingenic_drm_crtc_atomic_enable(struct drm_crtc *crtc,
>  					   struct drm_atomic_state *state)
>  {
> @@ -237,17 +249,11 @@ static void 
> ingenic_drm_crtc_atomic_enable(struct drm_crtc *crtc,
>  	if (WARN_ON(IS_ERR(priv_state)))
>  		return;
> 
> -	regmap_write(priv->map, JZ_REG_LCD_STATE, 0);
> -
>  	/* Set addresses of our DMA descriptor chains */
>  	next_id = priv_state->use_palette ? HWDESC_PALETTE : 0;
>  	regmap_write(priv->map, JZ_REG_LCD_DA0, dma_hwdesc_addr(priv, 
> next_id));
>  	regmap_write(priv->map, JZ_REG_LCD_DA1, dma_hwdesc_addr(priv, 1));
> 
> -	regmap_update_bits(priv->map, JZ_REG_LCD_CTRL,
> -			   JZ_LCD_CTRL_ENABLE | JZ_LCD_CTRL_DISABLE,
> -			   JZ_LCD_CTRL_ENABLE);
> -
>  	drm_crtc_vblank_on(crtc);
>  }
> 
> @@ -968,6 +974,7 @@ static const struct drm_encoder_helper_funcs 
> ingenic_drm_encoder_helper_funcs =
> 
>  static const struct drm_bridge_funcs ingenic_drm_bridge_funcs = {
>  	.attach			= ingenic_drm_bridge_attach,
> +	.atomic_enable		= ingenic_drm_bridge_atomic_enable,

Shouldn't we have a .atomic_disable() as well? If the CRTC is now 
enabled in the bridge's .atomic_enable, it would make sense to have it 
disabled in the .atomic_disable().

Cheers,
-Paul

>  	.atomic_check		= ingenic_drm_bridge_atomic_check,
>  	.atomic_reset		= drm_atomic_helper_bridge_reset,
>  	.atomic_duplicate_state	= drm_atomic_helper_bridge_duplicate_state,
> --
> 2.35.1
>