From: Thierry Reding treding@nvidia.com
By default the PM core prevents devices from being runtime suspended during system sleep. This is needed to avoid some common cases where devices cannot be properly resumed because their parents are runtime suspended at an unfortunate point in time.
However, there are cases where suspend/resume works in a way that it becomes possible for devices to be runtime suspended at system sleep time. In fact, for some devices runtime suspension can be equivalent to their state in system sleep.
Typically this would be solved by making the runtime suspend/resume callbacks the same as the system suspend/resume callbacks. For some subsystems it isn't quite that simple, unfortunately.
For example, the DRM subsystem has subsystem-level suspend/resume helpers that control how display pipelines are shut down on suspend and brought up again on resume. This procedure is the same as their operation under normal circumstances (when the user switches on/off a subset of the displays in their configuration). These helpers are carefully ordering the operations to make sure the right sequences between connectors, encoders and display controllers are respected.
In order for suspend/resume to not get in the way of the sequencing that's already happening at the subsystem level, allow the devices involved in the display pipelines to runtime suspend during system sleep.
Signed-off-by: Thierry Reding treding@nvidia.com --- drivers/gpu/drm/tegra/dc.c | 1 + drivers/gpu/drm/tegra/dsi.c | 1 + drivers/gpu/drm/tegra/hdmi.c | 1 + drivers/gpu/drm/tegra/hub.c | 1 + drivers/gpu/drm/tegra/sor.c | 1 + 5 files changed, 5 insertions(+)
diff --git a/drivers/gpu/drm/tegra/dc.c b/drivers/gpu/drm/tegra/dc.c index 2b9a25c977c0..386819b4662b 100644 --- a/drivers/gpu/drm/tegra/dc.c +++ b/drivers/gpu/drm/tegra/dc.c @@ -2506,6 +2506,7 @@ static int tegra_dc_probe(struct platform_device *pdev) }
platform_set_drvdata(pdev, dc); + pm_runtime_always_allow(&pdev->dev); pm_runtime_enable(&pdev->dev);
INIT_LIST_HEAD(&dc->client.list); diff --git a/drivers/gpu/drm/tegra/dsi.c b/drivers/gpu/drm/tegra/dsi.c index a5d47e301c5f..683a27f9ba52 100644 --- a/drivers/gpu/drm/tegra/dsi.c +++ b/drivers/gpu/drm/tegra/dsi.c @@ -1552,6 +1552,7 @@ static int tegra_dsi_probe(struct platform_device *pdev) }
platform_set_drvdata(pdev, dsi); + pm_runtime_always_allow(&pdev->dev); pm_runtime_enable(&pdev->dev);
INIT_LIST_HEAD(&dsi->client.list); diff --git a/drivers/gpu/drm/tegra/hdmi.c b/drivers/gpu/drm/tegra/hdmi.c index 50269ffbcb6b..2562bf607be1 100644 --- a/drivers/gpu/drm/tegra/hdmi.c +++ b/drivers/gpu/drm/tegra/hdmi.c @@ -1664,6 +1664,7 @@ static int tegra_hdmi_probe(struct platform_device *pdev) }
platform_set_drvdata(pdev, hdmi); + pm_runtime_always_allow(&pdev->dev); pm_runtime_enable(&pdev->dev);
INIT_LIST_HEAD(&hdmi->client.list); diff --git a/drivers/gpu/drm/tegra/hub.c b/drivers/gpu/drm/tegra/hub.c index e56c0f7d3a13..aced537ac990 100644 --- a/drivers/gpu/drm/tegra/hub.c +++ b/drivers/gpu/drm/tegra/hub.c @@ -844,6 +844,7 @@ static int tegra_display_hub_probe(struct platform_device *pdev) return err;
platform_set_drvdata(pdev, hub); + pm_runtime_always_allow(&pdev->dev); pm_runtime_enable(&pdev->dev);
INIT_LIST_HEAD(&hub->client.list); diff --git a/drivers/gpu/drm/tegra/sor.c b/drivers/gpu/drm/tegra/sor.c index a68d3b36b972..20058f11bf81 100644 --- a/drivers/gpu/drm/tegra/sor.c +++ b/drivers/gpu/drm/tegra/sor.c @@ -3833,6 +3833,7 @@ static int tegra_sor_probe(struct platform_device *pdev) }
platform_set_drvdata(pdev, sor); + pm_runtime_always_allow(&pdev->dev); pm_runtime_enable(&pdev->dev);
/*