• Thierry Reding's avatar
    drm/tegra: Do not implement runtime PM · fd67e9c6
    Thierry Reding authored
    The Tegra DRM driver heavily relies on the implementations for runtime
    suspend/resume to be called at specific times. Unfortunately, there are
    some cases where that doesn't work. One example is if the user disables
    runtime PM for a given subdevice. Another example is that the PM core
    acquires a reference to runtime PM during system sleep, effectively
    preventing devices from going into low power modes. This is intentional
    to avoid nasty race conditions, but it also causes system sleep to not
    function properly on all Tegra systems.
    
    Fix this by not implementing runtime PM at all. Instead, a minimal,
    reference-counted suspend/resume infrastructure is added to the host1x
    bus. This has the benefit that it can be used regardless of the system
    power state (or any transitions we might be in), or whether or not the
    user allows runtime PM.
    
    Atomic modesetting guarantees that these functions will end up being
    called at the right point in time, so the pitfalls for the more generic
    runtime PM do not apply here.
    Signed-off-by: default avatarThierry Reding <treding@nvidia.com>
    fd67e9c6
dsi.c 42.2 KB