[PATCH v5] drm/rockchip: Add device links for master and components

[Enric Balletbo i Serra]

From: Jeffy Chen <jeffy.chen at rock-chips.com>

Since we are trying to access components' resources in the master's
suspend/resume PM callbacks(e.g. panel), add device links to correct
the suspend/resume and shutdown ordering.

Signed-off-by: Jeffy Chen <jeffy.chen at rock-chips.com>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo at collabora.com>
---
Hi,

This is an attempt to revive a patch [1] that was sent last October. Sean
Paul requested some changes but I think that never was send a v5 version.
The patch fixes and issue where backlight panel is not correctly recoved
after a resume. This was tested on top of current linux-next plus the
latest series of Thierry's patches [2]

[1] https://patchwork.kernel.org/patch/10011595/
[2] https://lkml.org/lkml/2018/1/30/621

Changes in v5:
Address the comments from Sean.
- Create a helper to do the cleanup.
- Call the helper in rockchip_drm_match_add and where needed.
Changes in v4: None
Changes in v3: None
Changes in v2:
Use device link to correct the suspend/resume and shutdown ordering,
instead of converting rockchip spi's suspend/resume PM callbacks to
late suspend/resume PM callbacks.

Thanks,
 Enric

 drivers/gpu/drm/rockchip/rockchip_drm_drv.c | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
index 0609113d6a71..f814d37b1db2 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
@@ -314,6 +314,14 @@ static int compare_dev(struct device *dev, void *data)
 	return dev == (struct device *)data;
 }
 
+static void rockchip_drm_match_remove(struct device *dev)
+{
+	struct device_link *link;
+
+	list_for_each_entry(link, &dev->links.consumers, s_node)
+		device_link_del(link);
+}
+
 static struct component_match *rockchip_drm_match_add(struct device *dev)
 {
 	struct component_match *match = NULL;
@@ -331,10 +339,15 @@ static struct component_match *rockchip_drm_match_add(struct device *dev)
 
 			if (!d)
 				break;
+
+			device_link_add(dev, d, DL_FLAG_STATELESS);
 			component_match_add(dev, &match, compare_dev, d);
 		} while (true);
 	}
 
+	if (IS_ERR(match))
+		rockchip_drm_match_remove(dev);
+
 	return match ?: ERR_PTR(-ENODEV);
 }
 
@@ -411,13 +424,21 @@ static int rockchip_drm_platform_probe(struct platform_device *pdev)
 	if (IS_ERR(match))
 		return PTR_ERR(match);
 
-	return component_master_add_with_match(dev, &rockchip_drm_ops, match);
+	ret = component_master_add_with_match(dev, &rockchip_drm_ops, match);
+	if (ret < 0) {
+		rockchip_drm_match_remove(dev);
+		return ret;
+	}
+
+	return 0;
 }
 
 static int rockchip_drm_platform_remove(struct platform_device *pdev)
 {
 	component_master_del(&pdev->dev, &rockchip_drm_ops);
 
+	rockchip_drm_match_remove(&pdev->dev);
+
 	return 0;
 }
 
-- 
2.15.1