[PATCH v2 11/11] drm/rockchip: dw_hdmi: Use resume_early pm ops for system suspend

[Jonas Karlman]

rockchip_drm_sys_resume()/drm_mode_config_helper_resume() is called
before the resume pm ops of dw-hdmi. This result in an atomic_enable()
before dw_hdmi_rockchip_resume()/dw_hdmi_resume() is called.

Resume (without changes):
- rockchip_drm_sys_resume()
  - drm_mode_config_helper_resume()
    - atomic_enable()
- dw_hdmi_rockchip_resume()
  - dw_hdmi_resume()
    - dw_hdmi_init_hw()

Change to use resume_early pm ops for system suspend to ensure pm ops
for dw-hdmi is run before rockchip-drm pm ops. Also fix a possible NULL
pointer dereference timing issue while at it.

Resume (with changes):
- dw_hdmi_rockchip_resume_early()
  - dw_hdmi_resume()
    - dw_hdmi_init_hw()
- rockchip_drm_sys_resume()
  - drm_mode_config_helper_resume()
    - atomic_enable()

Signed-off-by: Jonas Karlman <jonas at kwiboo.se>
---
v2: New patch

This can be tested using CONFIG_PM_DEBUG with a simulated suspend:
  echo N > /sys/module/printk/parameters/console_suspend
  echo 1 > /sys/power/pm_debug_messages
  echo platform > /sys/power/pm_test
  echo mem > /sys/power/state
or using something like following for real suspend/resume:
  echo N > /sys/module/printk/parameters/console_suspend
  rtcwake -m mem -s 5

Note that RK356x has an issue related to EHCI/OHCI and a missing USBPHY
clock reference during suspend, and GPU during resume (mainline TF-A).
A separate patch to address the ECHI/OHCI issue will be sent.
---
 drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
index 0133a4b67b3b..ac6a48ce8642 100644
--- a/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
@@ -692,17 +692,18 @@ static void dw_hdmi_rockchip_remove(struct platform_device *pdev)
 	component_del(&pdev->dev, &dw_hdmi_rockchip_ops);
 }
 
-static int __maybe_unused dw_hdmi_rockchip_resume(struct device *dev)
+static int __maybe_unused dw_hdmi_rockchip_resume_early(struct device *dev)
 {
 	struct rockchip_hdmi *hdmi = dev_get_drvdata(dev);
 
-	dw_hdmi_resume(hdmi->hdmi);
+	if (hdmi)
+		dw_hdmi_resume(hdmi->hdmi);
 
 	return 0;
 }
 
 static const struct dev_pm_ops dw_hdmi_rockchip_pm = {
-	SET_SYSTEM_SLEEP_PM_OPS(NULL, dw_hdmi_rockchip_resume)
+	SET_LATE_SYSTEM_SLEEP_PM_OPS(NULL, dw_hdmi_rockchip_resume_early)
 };
 
 struct platform_driver dw_hdmi_rockchip_pltfm_driver = {
-- 
2.54.0