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- From f54692dc8ff6e0aecf27fdd2ebaed8e22d04f053 Mon Sep 17 00:00:00 2001
- From: wm4 <wm4@nowhere>
- Date: Wed, 13 Jan 2016 19:44:24 +0100
- Subject: [PATCH] bcm2835: only allow stereo if analogue jack is selected
- Sending more than 2 channels to videocore while outputting to analogue
- mysteriously outputs heavy artifacts. So just paint it over with a
- hack: if analogue is explicitly selected as destination, do not
- reporting support for anything other than stereo.
- I'm not sure how to deal with the auto case (destination 0). There's
- probably way to retrieve this and even to listen to plug events, but
- I didn't find one yet, and it's probably not worth the trouble. Just
- don't use this setting, I guess. Unless you like noise.
- Changing the setting while an audio stream is active also doesn't
- work properly. We could probably interrupt running streams by
- returning ENODEV or using kernel hotplug stuff (maybe), but that
- also doesn't seem worth the trouble.
- ---
- sound/arm/bcm2835-ctl.c | 12 ++++++++++++
- 1 file changed, 12 insertions(+)
- --- a/sound/arm/bcm2835-ctl.c
- +++ b/sound/arm/bcm2835-ctl.c
- @@ -423,9 +423,16 @@ static struct cea_channel_speaker_alloca
- { .ca_index = 0x31, .speakers = { FRW, FLW, RR, RL, FC, LFE, FR, FL } },
- };
-
- +static int uses_analogue(bcm2835_chip_t *chip)
- +{
- + return chip->dest == 1;
- +}
- +
- static int snd_bcm2835_chmap_ctl_tlv(struct snd_kcontrol *kcontrol, int op_flag,
- unsigned int size, unsigned int __user *tlv)
- {
- + struct snd_pcm_chmap *info = snd_kcontrol_chip(kcontrol);
- + bcm2835_chip_t *chip = info->private_data;
- unsigned int __user *dst;
- int count = 0;
- int i;
- @@ -442,6 +449,9 @@ static int snd_bcm2835_chmap_ctl_tlv(str
- int chs_bytes;
- int c;
-
- + if (i > 0 && uses_analogue(chip))
- + break;
- +
- for (c = 0; c < 8; c++) {
- if (ch->speakers[c])
- num_chs++;
- @@ -552,6 +562,8 @@ static int snd_bcm2835_chmap_ctl_put(str
- int matches = 1;
- int cur = 0;
- int x;
- + if (i > 0 && uses_analogue(chip))
- + break;
- memset(remap, 0, sizeof(remap));
- for (x = 0; x < substream->runtime->channels; x++) {
- int sp = ucontrol->value.integer.value[x];
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