video: mxcfb: blank/unblank to save power

This patch does two things.

1)  It makes sure the display is unblanked when first connected.
This gives us a good user experience where if the framebuffer is
blanked and then a device is plugged in nothing turns on.

2)  After the hdmi device is registered we tell the IPU to blank
the display, then on subsequent connect/disconnect events we
unblank/blank the screens as needed.  This makes sure that the
ipu is always disabled if we aren't using it and if you don't have
a monitor attached saves about 80mA's of constant power usage.

Overall this provides a significant power savings for headless
systems, and also doesn't block the bus-frequency driver from
kicking in if no display is attached.

Signed-off-by: Jon Nettleton <jon@solid-run.com>

Author: jnettlet

drivers/video/fbdev/mxc/mxc_hdmi.c

@@ -2063,6 +2063,10 @@ static void mxc_hdmi_cable_connected(struct mxc_hdmi *hdmi)
 	mxc_hdmi_set_mode(hdmi,
 		memcmp(&modelist, &hdmi->fbi->modelist, sizeof(modelist)) != 0);
 
+	console_lock();
+	fb_blank(hdmi->fbi, FB_BLANK_UNBLANK);
+	console_unlock();
+
 	dev_dbg(&hdmi->pdev->dev, "%s exit\n", __func__);
 }
 
@@ -2088,6 +2092,10 @@ static void mxc_hdmi_cable_disconnected(struct mxc_hdmi *hdmi)
 
 	dev_dbg(&hdmi->pdev->dev, "%s\n", __func__);
 
+	console_lock();
+	fb_blank(hdmi->fbi, FB_BLANK_POWERDOWN);
+	console_unlock();
+
 	/* Save CEC clock */
 	clkdis = hdmi_readb(HDMI_MC_CLKDIS) & HDMI_MC_CLKDIS_CECCLK_DISABLE;
 	clkdis |= ~HDMI_MC_CLKDIS_CECCLK_DISABLE;
@@ -2373,6 +2381,8 @@ static void mxc_hdmi_fb_registered(struct mxc_hdmi *hdmi)
 	if (hdmi->fb_reg)
 		return;
 
+	fb_blank(hdmi->fbi, FB_BLANK_POWERDOWN);
+
 	spin_lock_irqsave(&hdmi->irq_lock, flags);
 
 	dev_dbg(&hdmi->pdev->dev, "%s\n", __func__);