linux-kernel - Re: [PATCH 1/8] drm: bridge: dw_hdmi: Call poweron/poweroff from atomic enable/disable

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Date: Mon, 24 Jun 2024 11:23:04 +0200
From: Neil Armstrong <neil.armstrong@...aro.org>
To: Jonas Karlman <jonas@...boo.se>, Andrzej Hajda <andrzej.hajda@...el.com>,
 Robert Foss <rfoss@...nel.org>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
 Jernej Skrabec <jernej.skrabec@...il.com>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/8] drm: bridge: dw_hdmi: Call poweron/poweroff from
 atomic enable/disable

On 11/06/2024 17:50, Jonas Karlman wrote:
> Change to only call poweron/poweroff from atomic_enable/atomic_disable
> ops instead of trying to keep a bridge_is_on state and poweron/off in
> the hotplug irq handler.
> 
> A benefit of this is that drm mode_config mutex is always held at
> poweron/off, something that may reduce the need for our own mutex.
> 
> Signed-off-by: Jonas Karlman <jonas@...boo.se>
> ---
>   drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 33 ++---------------------
>   1 file changed, 2 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> index 9f2bc932c371..34bc6f4754b8 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> @@ -172,7 +172,6 @@ struct dw_hdmi {
>   	enum drm_connector_force force;	/* mutex-protected force state */
>   	struct drm_connector *curr_conn;/* current connector (only valid when !disabled) */
>   	bool disabled;			/* DRM has disabled our bridge */
> -	bool bridge_is_on;		/* indicates the bridge is on */
>   	bool rxsense;			/* rxsense state */
>   	u8 phy_mask;			/* desired phy int mask settings */
>   	u8 mc_clkdis;			/* clock disable register */
> @@ -2383,8 +2382,6 @@ static void initialize_hdmi_ih_mutes(struct dw_hdmi *hdmi)
>   
>   static void dw_hdmi_poweron(struct dw_hdmi *hdmi)
>   {
> -	hdmi->bridge_is_on = true;
> -
>   	/*
>   	 * The curr_conn field is guaranteed to be valid here, as this function
>   	 * is only be called when !hdmi->disabled.
> @@ -2398,30 +2395,6 @@ static void dw_hdmi_poweroff(struct dw_hdmi *hdmi)
>   		hdmi->phy.ops->disable(hdmi, hdmi->phy.data);
>   		hdmi->phy.enabled = false;
>   	}
> -
> -	hdmi->bridge_is_on = false;
> -}
> -
> -static void dw_hdmi_update_power(struct dw_hdmi *hdmi)
> -{
> -	int force = hdmi->force;
> -
> -	if (hdmi->disabled) {
> -		force = DRM_FORCE_OFF;
> -	} else if (force == DRM_FORCE_UNSPECIFIED) {
> -		if (hdmi->rxsense)
> -			force = DRM_FORCE_ON;
> -		else
> -			force = DRM_FORCE_OFF;
> -	}

This means we always poweron the bridge even if rxsense is false ?

Neil

> -
> -	if (force == DRM_FORCE_OFF) {
> -		if (hdmi->bridge_is_on)
> -			dw_hdmi_poweroff(hdmi);
> -	} else {
> -		if (!hdmi->bridge_is_on)
> -			dw_hdmi_poweron(hdmi);
> -	}
>   }
>   
>   /*
> @@ -2546,7 +2519,6 @@ static void dw_hdmi_connector_force(struct drm_connector *connector)
>   
>   	mutex_lock(&hdmi->mutex);
>   	hdmi->force = connector->force;
> -	dw_hdmi_update_power(hdmi);
>   	dw_hdmi_update_phy_mask(hdmi);
>   	mutex_unlock(&hdmi->mutex);
>   }
> @@ -2955,7 +2927,7 @@ static void dw_hdmi_bridge_atomic_disable(struct drm_bridge *bridge,
>   	mutex_lock(&hdmi->mutex);
>   	hdmi->disabled = true;
>   	hdmi->curr_conn = NULL;
> -	dw_hdmi_update_power(hdmi);
> +	dw_hdmi_poweroff(hdmi);
>   	dw_hdmi_update_phy_mask(hdmi);
>   	handle_plugged_change(hdmi, false);
>   	mutex_unlock(&hdmi->mutex);
> @@ -2974,7 +2946,7 @@ static void dw_hdmi_bridge_atomic_enable(struct drm_bridge *bridge,
>   	mutex_lock(&hdmi->mutex);
>   	hdmi->disabled = false;
>   	hdmi->curr_conn = connector;
> -	dw_hdmi_update_power(hdmi);
> +	dw_hdmi_poweron(hdmi);
>   	dw_hdmi_update_phy_mask(hdmi);
>   	handle_plugged_change(hdmi, true);
>   	mutex_unlock(&hdmi->mutex);
> @@ -3073,7 +3045,6 @@ void dw_hdmi_setup_rx_sense(struct dw_hdmi *hdmi, bool hpd, bool rx_sense)
>   		if (hpd)
>   			hdmi->rxsense = true;
>   
> -		dw_hdmi_update_power(hdmi);
>   		dw_hdmi_update_phy_mask(hdmi);
>   	}
>   	mutex_unlock(&hdmi->mutex);