OMAPDSS: HDMI: PHY burnout fix

A hardware bug in the OMAP4 HDMI PHY causes physical damage to the board
if the HDMI PHY is kept powered on when the cable is not connected.

This patch solves the problem by adding hot-plug-detection into the HDMI
IP driver. This is not a real HPD support in the sense that nobody else
than the IP driver gets to know about the HPD events, but is only meant
to fix the HW bug.

The strategy is simple: If the display device is turned off by the user,
the PHY power is set to OFF. When the display device is turned on by the
user, the PHY power is set either to LDOON or TXON, depending on whether
the HDMI cable is connected.

The reason to avoid PHY OFF when the display device is on, but the cable
is disconnected, is that when the PHY is turned OFF, the HDMI IP is not
"ticking" and thus the DISPC does not receive pixel clock from the HDMI
IP. This would, for example, prevent any VSYNCs from happening, and
would thus affect the users of omapdss. By using LDOON when the cable is
disconnected we'll avoid the HW bug, but keep the HDMI working as usual
from the user's point of view.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/video/omap2/dss/ti_hdmi.h b/drivers/video/omap2/dss/ti_hdmi.h
index 7503f7f619a..50dadba5070 100644
--- a/drivers/video/omap2/dss/ti_hdmi.h
+++ b/drivers/video/omap2/dss/ti_hdmi.h
@@ -126,6 +126,10 @@ struct hdmi_ip_data {
 	const struct ti_hdmi_ip_ops *ops;
 	struct hdmi_config cfg;
 	struct hdmi_pll_info pll_data;
+
+	/* ti_hdmi_4xxx_ip private data. These should be in a separate struct */
+	int hpd_gpio;
+	bool phy_tx_enabled;
 };
 int ti_hdmi_4xxx_phy_enable(struct hdmi_ip_data *ip_data);
 void ti_hdmi_4xxx_phy_disable(struct hdmi_ip_data *ip_data);