• Maxime Ripard's avatar
    drm/vc4: crtc: Fix runtime_pm reference counting · 6764eb69
    Maxime Ripard authored
    At boot on the BCM2711, if the HDMI controllers are running, the CRTC
    driver will disable itself and its associated HDMI controller to work
    around a hardware bug that would leave some pixels stuck in a FIFO.
    
    In order to avoid that issue, we need to run some operations in lockstep
    between the CRTC and HDMI controller, and we need to make sure the HDMI
    controller will be powered properly.
    
    However, since we haven't enabled it through KMS, the runtime_pm state
    is off at this point so we need to make sure the device is powered
    through pm_runtime_resume_and_get, and once the operations are complete,
    we call pm_runtime_put.
    
    However, the HDMI controller will do that itself in its
    post_crtc_powerdown, which means we'll end up calling pm_runtime_put for
    a single pm_runtime_get, throwing the reference counting off. Let's
    remove the pm_runtime_put call in the CRTC code in order to have the
    proper counting.
    
    Fixes: bca10db6 ("drm/vc4: crtc: Make sure the HDMI controller is powered when disabling")
    Signed-off-by: default avatarMaxime Ripard <maxime@cerno.tech>
    Reviewed-by: default avatarJavier Martinez Canillas <javierm@redhat.com>
    Link: https://patchwork.freedesktop.org/patch/msgid/20220203102003.1114673-1-maxime@cerno.tech
    6764eb69
vc4_crtc.c 36.5 KB