011f2c26f1
As usual these patches were extracted and rebased from the raspberry pi repo: https://github.com/raspberrypi/linux/tree/rpi-4.4.y Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
61 lines
2.1 KiB
Diff
61 lines
2.1 KiB
Diff
From f54692dc8ff6e0aecf27fdd2ebaed8e22d04f053 Mon Sep 17 00:00:00 2001
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From: wm4 <wm4@nowhere>
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Date: Wed, 13 Jan 2016 19:44:24 +0100
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Subject: [PATCH] bcm2835: only allow stereo if analogue jack is selected
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Sending more than 2 channels to videocore while outputting to analogue
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mysteriously outputs heavy artifacts. So just paint it over with a
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hack: if analogue is explicitly selected as destination, do not
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reporting support for anything other than stereo.
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I'm not sure how to deal with the auto case (destination 0). There's
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probably way to retrieve this and even to listen to plug events, but
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I didn't find one yet, and it's probably not worth the trouble. Just
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don't use this setting, I guess. Unless you like noise.
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Changing the setting while an audio stream is active also doesn't
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work properly. We could probably interrupt running streams by
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returning ENODEV or using kernel hotplug stuff (maybe), but that
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also doesn't seem worth the trouble.
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---
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sound/arm/bcm2835-ctl.c | 12 ++++++++++++
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1 file changed, 12 insertions(+)
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--- a/sound/arm/bcm2835-ctl.c
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+++ b/sound/arm/bcm2835-ctl.c
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@@ -423,9 +423,16 @@ static struct cea_channel_speaker_alloca
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{ .ca_index = 0x31, .speakers = { FRW, FLW, RR, RL, FC, LFE, FR, FL } },
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};
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+static int uses_analogue(bcm2835_chip_t *chip)
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+{
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+ return chip->dest == 1;
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+}
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+
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static int snd_bcm2835_chmap_ctl_tlv(struct snd_kcontrol *kcontrol, int op_flag,
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unsigned int size, unsigned int __user *tlv)
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{
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+ struct snd_pcm_chmap *info = snd_kcontrol_chip(kcontrol);
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+ bcm2835_chip_t *chip = info->private_data;
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unsigned int __user *dst;
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int count = 0;
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int i;
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@@ -442,6 +449,9 @@ static int snd_bcm2835_chmap_ctl_tlv(str
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int chs_bytes;
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int c;
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+ if (i > 0 && uses_analogue(chip))
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+ break;
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+
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for (c = 0; c < 8; c++) {
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if (ch->speakers[c])
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num_chs++;
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@@ -552,6 +562,8 @@ static int snd_bcm2835_chmap_ctl_put(str
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int matches = 1;
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int cur = 0;
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int x;
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+ if (i > 0 && uses_analogue(chip))
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+ break;
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memset(remap, 0, sizeof(remap));
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for (x = 0; x < substream->runtime->channels; x++) {
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int sp = ucontrol->value.integer.value[x];
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