drm/msm/hdmi: Fix connector detect when there is no HPD gpio

Some platforms may not have a HPD gpio line to detect Hot Plug signal from
the connector. They need to rely only on reading REG_HDMI_HPD_INT_STATUS
for HPD.

Modify hdmi_connector_detect logic such that it checks for HPD only using
the status register if there is no HPD gpio.
Signed-off-by: NArchit Taneja <architt@codeaurora.org>
Signed-off-by: NRob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/hdmi/hdmi_connector.c

@@ -301,9 +301,18 @@ static enum drm_connector_status hdmi_connector_detect(
 {
 	struct hdmi_connector *hdmi_connector = to_hdmi_connector(connector);
 	struct hdmi *hdmi = hdmi_connector->hdmi;
+	const struct hdmi_platform_config *config = hdmi->config;
+	struct hdmi_gpio_data hpd_gpio = config->gpios[HPD_GPIO_INDEX];
 	enum drm_connector_status stat_gpio, stat_reg;
 	int retry = 20;
 
+	/*
+	 * some platforms may not have hpd gpio. Rely only on the status
+	 * provided by REG_HDMI_HPD_INT_STATUS in this case.
+	 */
+	if (hpd_gpio.num == -1)
+		return detect_reg(hdmi);
+
 	do {
 		stat_gpio = detect_gpio(hdmi);
 		stat_reg  = detect_reg(hdmi);