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>

diff --git a/arch/arm/mach-omap2/board-4430sdp.c b/arch/arm/mach-omap2/board-4430sdp.c
index cd6ec517a929b62c247d5ddc5d99aa2edef97505..0ce758edaad27273293f3107898ce4b0b13b5dda 100644 (file)
--- 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 e1b196361f95e10eeebebb5b25dd9067d60bf8ac..370c4b428888ff5e6921c14a02a91471080ad034 100644 (file)
--- 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[] = {

diff --git a/drivers/video/omap2/dss/hdmi.c b/drivers/video/omap2/dss/hdmi.c
index c39f9c3a92cf1a6bd0ddb6cc028f47754d20697d..d7aa3b056529e9469a8e3c0346ebbe421a2df1be 100644 (file)
--- a/drivers/video/omap2/dss/hdmi.c
+++ b/drivers/video/omap2/dss/hdmi.c
@@ -497,6 +497,7 @@ bool omapdss_hdmi_detect(void)
 
 int omapdss_hdmi_display_enable(struct omap_dss_device *dssdev)
 {
+       struct omap_dss_hdmi_data *priv = dssdev->data;
        int r = 0;
 
        DSSDBG("ENTER hdmi_display_enable\n");
@@ -509,6 +510,8 @@ int omapdss_hdmi_display_enable(struct omap_dss_device *dssdev)
                goto err0;
        }
 
+       hdmi.ip_data.hpd_gpio = priv->hpd_gpio;
+
        r = omap_dss_start_device(dssdev);
        if (r) {
                DSSERR("failed to start device\n");

diff --git a/drivers/video/omap2/dss/ti_hdmi.h b/drivers/video/omap2/dss/ti_hdmi.h
index 7503f7f619a7fe43b7be266f04e9bf4cd7c8579a..50dadba5070a6fc862cb514979e30e7faf8f9f34 100644 (file)
--- 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);

diff --git a/drivers/video/omap2/dss/ti_hdmi_4xxx_ip.c b/drivers/video/omap2/dss/ti_hdmi_4xxx_ip.c
index 9af81f18f1633ffaaeae842d922f8800cd9d285c..2d72334ca3da9a7d3bac43fba0c7e1ce6c26621e 100644 (file)
--- a/drivers/video/omap2/dss/ti_hdmi_4xxx_ip.c
+++ b/drivers/video/omap2/dss/ti_hdmi_4xxx_ip.c
@@ -28,6 +28,7 @@
 #include <linux/delay.h>
 #include <linux/string.h>
 #include <linux/seq_file.h>
+#include <linux/gpio.h>
 
 #include "ti_hdmi_4xxx_ip.h"
 #include "dss.h"
@@ -223,6 +224,49 @@ void ti_hdmi_4xxx_pll_disable(struct hdmi_ip_data *ip_data)
        hdmi_set_pll_pwr(ip_data, HDMI_PLLPWRCMD_ALLOFF);
 }
 
+static int hdmi_check_hpd_state(struct hdmi_ip_data *ip_data)
+{
+       unsigned long flags;
+       bool hpd;
+       int r;
+       /* this should be in ti_hdmi_4xxx_ip private data */
+       static DEFINE_SPINLOCK(phy_tx_lock);
+
+       spin_lock_irqsave(&phy_tx_lock, flags);
+
+       hpd = gpio_get_value(ip_data->hpd_gpio);
+
+       if (hpd == ip_data->phy_tx_enabled) {
+               spin_unlock_irqrestore(&phy_tx_lock, flags);
+               return 0;
+       }
+
+       if (hpd)
+               r = hdmi_set_phy_pwr(ip_data, HDMI_PHYPWRCMD_TXON);
+       else
+               r = hdmi_set_phy_pwr(ip_data, HDMI_PHYPWRCMD_LDOON);
+
+       if (r) {
+               DSSERR("Failed to %s PHY TX power\n",
+                               hpd ? "enable" : "disable");
+               goto err;
+       }
+
+       ip_data->phy_tx_enabled = hpd;
+err:
+       spin_unlock_irqrestore(&phy_tx_lock, flags);
+       return r;
+}
+
+static irqreturn_t hpd_irq_handler(int irq, void *data)
+{
+       struct hdmi_ip_data *ip_data = data;
+
+       hdmi_check_hpd_state(ip_data);
+
+       return IRQ_HANDLED;
+}
+
 int ti_hdmi_4xxx_phy_enable(struct hdmi_ip_data *ip_data)
 {
        u16 r = 0;
@@ -232,10 +276,6 @@ int ti_hdmi_4xxx_phy_enable(struct hdmi_ip_data *ip_data)
        if (r)
                return r;
 
-       r = hdmi_set_phy_pwr(ip_data, HDMI_PHYPWRCMD_TXON);
-       if (r)
-               return r;
-
        /*
         * Read address 0 in order to get the SCP reset done completed
         * Dummy access performed to make sure reset is done
@@ -257,12 +297,32 @@ int ti_hdmi_4xxx_phy_enable(struct hdmi_ip_data *ip_data)
        /* Write to phy address 3 to change the polarity control */
        REG_FLD_MOD(phy_base, HDMI_TXPHY_PAD_CFG_CTRL, 0x1, 27, 27);
 
+       r = request_threaded_irq(gpio_to_irq(ip_data->hpd_gpio),
+                       NULL, hpd_irq_handler,
+                       IRQF_DISABLED | IRQF_TRIGGER_RISING |
+                       IRQF_TRIGGER_FALLING, "hpd", ip_data);
+       if (r) {
+               DSSERR("HPD IRQ request failed\n");
+               hdmi_set_phy_pwr(ip_data, HDMI_PHYPWRCMD_OFF);
+               return r;
+       }
+
+       r = hdmi_check_hpd_state(ip_data);
+       if (r) {
+               free_irq(gpio_to_irq(ip_data->hpd_gpio), ip_data);
+               hdmi_set_phy_pwr(ip_data, HDMI_PHYPWRCMD_OFF);
+               return r;
+       }
+
        return 0;
 }
 
 void ti_hdmi_4xxx_phy_disable(struct hdmi_ip_data *ip_data)
 {
+       free_irq(gpio_to_irq(ip_data->hpd_gpio), ip_data);
+
        hdmi_set_phy_pwr(ip_data, HDMI_PHYPWRCMD_OFF);
+       ip_data->phy_tx_enabled = false;
 }
 
 static int hdmi_core_ddc_init(struct hdmi_ip_data *ip_data)

diff --git a/include/video/omapdss.h b/include/video/omapdss.h
index 062b3b24ff1071047f6c7fe26c80d19c112fe311..483f67caa7ad42b0b360e99a3df2c1502dc1dae1 100644 (file)
--- a/include/video/omapdss.h
+++ b/include/video/omapdss.h
@@ -590,6 +590,11 @@ struct omap_dss_device {
        int (*get_backlight)(struct omap_dss_device *dssdev);
 };
 
+struct omap_dss_hdmi_data
+{
+       int hpd_gpio;
+};
+
 struct omap_dss_driver {
        struct device_driver driver;