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imx-drm: imx-drm-core: add basic suspend/resume support 

HDMI currently stops working after a system suspend/resume cycle.  The
cause is that the mode setting states in hardware gets lost and isn't
restored across the suspend/resume cycle.

The patch adds a very basic suspend/resume support to imx-drm driver,
and calls drm_helper_resume_force_mode() in .resume hook to restore the
mode setting states, so that HDMI can continue working after a system
suspend/resume cycle.

Since the suspend/resume hook can be called with drm_device pointer
being NULL from driver data, we need a check on the pointer in the
hooks.  And to avoid using a stale pointer from driver data, it also
clears driver data in .unload hook.

Signed-off-by: Shawn Guo <shawn.guo@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Shawn Guo 2014-09-10 22:43:51 +08:00 committed by Greg Kroah-Hartman
parent b46355f0f7
commit bfe945c8e1
1 changed files with 33 additions and 0 deletions
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33
drivers/staging/imx-drm/imx-drm-core.c
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@ -87,6 +87,8 @@ static int imx_drm_driver_unload(struct drm_device *drm)
drm_vblank_cleanup(drm);
drm_mode_config_cleanup(drm);
platform_set_drvdata(drm->platformdev, NULL);
return 0;
}
@ -648,6 +650,36 @@ static int imx_drm_platform_remove(struct platform_device *pdev)
return 0;
}
#ifdef CONFIG_PM_SLEEP
static int imx_drm_suspend(struct device *dev)
{
struct drm_device *drm_dev = dev_get_drvdata(dev);
/* The drm_dev is NULL before .load hook is called */
if (drm_dev == NULL)
return 0;
drm_kms_helper_poll_disable(drm_dev);
return 0;
}
static int imx_drm_resume(struct device *dev)
{
struct drm_device *drm_dev = dev_get_drvdata(dev);
if (drm_dev == NULL)
return 0;
drm_helper_resume_force_mode(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 */ },
@ -660,6 +692,7 @@ 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,
},
};