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 --- Greg,

This is a resend of '[PATCH v3] imx-drm: imx-drm-core: add suspend/resume support' [1], with a tiny change on the subject only.

Shawn

[1] http://thread.gmane.org/gmane.linux.ports.arm.kernel/349360

drivers/staging/imx-drm/imx-drm-core.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+)

diff --git a/drivers/staging/imx-drm/imx-drm-core.c b/drivers/staging/imx-drm/imx-drm-core.c index 6b22106534d8..41ff896d2ca9 100644 --- a/drivers/staging/imx-drm/imx-drm-core.c +++ b/drivers/staging/imx-drm/imx-drm-core.c @@ -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; }

@@ -647,6 +649,36 @@ 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 */ }, @@ -659,6 +691,7 @@ 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, }, };