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>

2 files changed, 10 insertions, 0 deletions

diff --git a/arch/arm/mach-omap2/board-4430sdp.c b/arch/arm/mach-omap2/board-4430sdp.c
index cd6ec517a929..0ce758edaad2 100644
--- a/arch/arm/mach-omap2/board-4430sdp.c
+++ b/arch/arm/mach-omap2/board-4430sdp.c
@@ -732,6 +732,10 @@ static void sdp4430_lcd_init(void)
                 pr_err("%s: Could not get lcd2_reset_gpio\n", __func__);
 }
 
+static struct omap_dss_hdmi_data sdp4430_hdmi_data = {
+        .hpd_gpio = HDMI_GPIO_HPD,
+};
+
 static struct omap_dss_device sdp4430_hdmi_device = {
         .name = "hdmi",
         .driver_name = "hdmi_panel",
@@ -739,6 +743,7 @@ static struct omap_dss_device sdp4430_hdmi_device = {
         .platform_enable = sdp4430_panel_enable_hdmi,
         .platform_disable = sdp4430_panel_disable_hdmi,
         .channel = OMAP_DSS_CHANNEL_DIGIT,
+        .data = &sdp4430_hdmi_data,
 };
 
 static struct picodlp_panel_data sdp4430_picodlp_pdata = {
diff --git a/arch/arm/mach-omap2/board-omap4panda.c b/arch/arm/mach-omap2/board-omap4panda.c
index e1b196361f95..370c4b428888 100644
--- a/arch/arm/mach-omap2/board-omap4panda.c
+++ b/arch/arm/mach-omap2/board-omap4panda.c
@@ -502,6 +502,10 @@ static void omap4_panda_panel_disable_hdmi(struct omap_dss_device *dssdev)
         gpio_free_array(panda_hdmi_gpios, ARRAY_SIZE(panda_hdmi_gpios));
 }
 
+static struct omap_dss_hdmi_data omap4_panda_hdmi_data = {
+        .hpd_gpio = HDMI_GPIO_HPD,
+};
+
 static struct omap_dss_device  omap4_panda_hdmi_device = {
         .name = "hdmi",
         .driver_name = "hdmi_panel",
@@ -509,6 +513,7 @@ static struct omap_dss_device  omap4_panda_hdmi_device = {
         .platform_enable = omap4_panda_panel_enable_hdmi,
         .platform_disable = omap4_panda_panel_disable_hdmi,
         .channel = OMAP_DSS_CHANNEL_DIGIT,
+        .data = &omap4_panda_hdmi_data,
 };
 
 static struct omap_dss_device *omap4_panda_dss_devices[] = {