[PATCH] imx-drm: imx-drm-core: add suspend/resume support

[Shawn Guo]

HDMI currently stops working after a system suspend/resume cycle.  It
turns out that the cause is the imx-hdmi encoder .dpms hook doesn't get
called from anywhere across suspend/resume cycle.

The patch follows what exynos drm driver does to walk the list of
connectors and call their .dpms function from suspend/resume hook.  And
the connectors' .dpms function will in turn filter down to the .dpms
hooks of encoders and CRTCs.

With this change, HDMI can continue working after a suspend/resume
cycle.

Signed-off-by: Shawn Guo <shawn.guo at freescale.com>
---
Tested with HDMI and LVDS.  It'd be great if someone can help test TVE
to ensure the patch doesn't break anything.

 drivers/staging/imx-drm/imx-drm-core.c | 39 ++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/drivers/staging/imx-drm/imx-drm-core.c b/drivers/staging/imx-drm/imx-drm-core.c
index def8280d7ee6..b0ea1f0ed32f 100644
--- a/drivers/staging/imx-drm/imx-drm-core.c
+++ b/drivers/staging/imx-drm/imx-drm-core.c
@@ -696,6 +696,44 @@ static int imx_drm_platform_remove(struct platform_device *pdev)
 	return 0;
 }
 
+#if CONFIG_PM_SLEEP
+static int imx_drm_suspend(struct device *dev)
+{
+	struct drm_device *drm_dev = dev_get_drvdata(dev);
+	struct drm_connector *connector;
+
+	drm_kms_helper_poll_disable(drm_dev);
+
+	drm_modeset_lock_all(drm_dev);
+	list_for_each_entry(connector, &drm_dev->mode_config.connector_list, head) {
+		if (connector->funcs->dpms)
+			connector->funcs->dpms(connector, DRM_MODE_DPMS_OFF);
+	}
+	drm_modeset_unlock_all(drm_dev);
+
+	return 0;
+}
+
+static int imx_drm_resume(struct device *dev)
+{
+	struct drm_device *drm_dev = dev_get_drvdata(dev);
+	struct drm_connector *connector;
+
+	drm_modeset_lock_all(drm_dev);
+	list_for_each_entry(connector, &drm_dev->mode_config.connector_list, head) {
+		if (connector->funcs->dpms)
+			connector->funcs->dpms(connector, DRM_MODE_DPMS_ON);
+	}
+	drm_modeset_unlock_all(drm_dev);
+
+	drm_kms_helper_poll_enable(drm_dev);
+
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(imx_drm_pm_ops, imx_drm_suspend, imx_drm_resume);
+
 static const struct of_device_id imx_drm_dt_ids[] = {
 	{ .compatible = "fsl,imx-display-subsystem", },
 	{ /* sentinel */ },
@@ -708,6 +746,7 @@ static struct platform_driver imx_drm_pdrv = {
 	.driver		= {
 		.owner	= THIS_MODULE,
 		.name	= "imx-drm",
+		.pm	= &imx_drm_pm_ops,
 		.of_match_table = imx_drm_dt_ids,
 	},
 };
-- 
1.9.1