From: Dom Cobley popcornmix@gmail.com
[ Upstream commit 1698ecb218eb82587dbfc71a2e26ded66e5ecf59 ]
Symptom is random switching of speakers when using multichannel.
Repeatedly running speakertest -c8 occasionally starts with channels jumbled. This is fixed with HD_CTL_WHOLSMP.
The other bit looks beneficial and apears harmless in testing so I'd suggest adding it too.
Documentation says: HD_CTL_WHILSMP_SET Wait for whole sample. When this bit is set MAI transmit will start only when there is at least one whole sample available in the fifo.
Documentation says: HD_CTL_CHALIGN_SET Channel Align When Overflow. This bit is used to realign the audio channels in case of an overflow. If this bit is set, after the detection of an overflow, equal amount of dummy words to the missing words will be written to fifo, filling up the broken sample and maintaining alignment.
Signed-off-by: Dom Cobley popcornmix@gmail.com Signed-off-by: Maxime Ripard maxime@cerno.tech Reviewed-by: Nicolas Saenz Julienne nsaenz@kernel.org Link: https://patchwork.freedesktop.org/patch/msgid/20210525132354.297468-7-maxime... Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/vc4/vc4_hdmi.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c index edee565334d8..155f305e7c4e 100644 --- a/drivers/gpu/drm/vc4/vc4_hdmi.c +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c @@ -1205,7 +1205,9 @@ static int vc4_hdmi_audio_trigger(struct snd_pcm_substream *substream, int cmd, HDMI_WRITE(HDMI_MAI_CTL, VC4_SET_FIELD(vc4_hdmi->audio.channels, VC4_HD_MAI_CTL_CHNUM) | - VC4_HD_MAI_CTL_ENABLE); + VC4_HD_MAI_CTL_WHOLSMP | + VC4_HD_MAI_CTL_CHALIGN | + VC4_HD_MAI_CTL_ENABLE); break; case SNDRV_PCM_TRIGGER_STOP: HDMI_WRITE(HDMI_MAI_CTL,