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drm/vc4: hdmi: Disable audio if dmas property is present but empty

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commit db2b927f8668adf3ac765e0921cd2720f5c04172 upstream.

The dmas property is used to hold the dmaengine channel used for audio
output.

Older device trees were missing that property, so if it's not there we
disable the audio output entirely.

However, some overlays have set an empty value to that property, mostly
to workaround the fact that overlays cannot remove a property. Let's add
a test for that case and if it's empty, let's disable it as well.

Cc: <stable@vger.kernel.org>
Signed-off-by: Phil Elwell <phil@raspberrypi.org>
Link: https://lore.kernel.org/r/20220613144800.326124-18-maxime@cerno.tech
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Phil Elwell 2022-06-13 16:47:44 +02:00 committed by Greg Kroah-Hartman
parent 1ff71d4f53
commit de63dbc296
1 changed files with 3 additions and 3 deletions
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6
drivers/gpu/drm/vc4/vc4_hdmi.c
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@ -1231,12 +1231,12 @@ static int vc4_hdmi_audio_init(struct vc4_hdmi *vc4_hdmi)
struct snd_soc_card *card = &vc4_hdmi->audio.card;
struct device *dev = &vc4_hdmi->pdev->dev;
const __be32 *addr;
int index;
int index, len;
int ret;
if (!of_find_property(dev->of_node, "dmas", NULL)) {
if (!of_find_property(dev->of_node, "dmas", &len) || !len) {
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;
}