openwrt/target/linux/bcm27xx/patches-5.15/950-0425-drm-vc4-A-present-but-empty-dmas-disables-audio.patch
Álvaro Fernández Rojas 20ea6adbf1 bcm27xx: add support for linux v5.15
Build system: x86_64
Build-tested: bcm2708, bcm2709, bcm2710, bcm2711
Run-tested: bcm2708/RPiB+, bcm2709/RPi3B, bcm2710/RPi3B, bcm2711/RPi4B

Signed-off-by: Marty Jones <mj8263788@gmail.com>
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
2022-05-17 15:11:22 +02:00

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From 96ddf993aa82e33e910110929816b6c83720dc99 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.org>
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 <phil@raspberrypi.org>
---
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
@@ -1692,10 +1692,12 @@ 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;
}