From 4de61df3c777ea6265d03be98b315c8644003ceb Mon Sep 17 00:00:00 2001 From: Phil Elwell Date: Wed, 31 Jul 2019 17:36:34 +0100 Subject: [PATCH] drm/vc4: A present but empty dmas disables audio Overlays are unable to remove properties in the base DTB, but they can overwrite them. Allow a present but empty 'dmas' property to also disable the HDMI audio interface. See: https://github.com/raspberrypi/linux/issues/2489 Signed-off-by: Phil Elwell --- drivers/gpu/drm/vc4/vc4_hdmi.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/drivers/gpu/drm/vc4/vc4_hdmi.c +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c @@ -1331,10 +1331,12 @@ static int vc4_hdmi_audio_init(struct vc const __be32 *addr; int index; int ret; + int len; - if (!of_find_property(dev->of_node, "dmas", NULL)) { + if (!of_find_property(dev->of_node, "dmas", &len) || + len == 0) { dev_warn(dev, - "'dmas' DT property is missing, no HDMI audio\n"); + "'dmas' DT property is missing or empty, no HDMI audio\n"); return 0; }