dab5a44067
n 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>
41 lines
1.5 KiB
Diff
41 lines
1.5 KiB
Diff
From 5710f5696b9db1108e1643a5967a5b576c32b8a0 Mon Sep 17 00:00:00 2001
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From: wm4 <wm4@nowhere>
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Date: Tue, 19 Apr 2016 16:29:41 +0200
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Subject: [PATCH] bcm2835: add fallback channel layouts if channel map API is
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not used
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Should be more useful than just forcing stereo.
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We can't match the exact legacy ALSA channel layouts, so this is a
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"best effort" hack.
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I'm not sure what happens if the application requests channel counts
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that are not power-of-2s. The channel map API hopefully forces
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applications which use the channel map API to request the correct
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count by adding padding channels, but the bare API enforces
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nothing. Possibly this could be added to rate_hw_constraint_channels
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at a later point.
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---
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sound/arm/bcm2835-vchiq.c | 11 ++++++++++-
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1 file changed, 10 insertions(+), 1 deletion(-)
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--- a/sound/arm/bcm2835-vchiq.c
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+++ b/sound/arm/bcm2835-vchiq.c
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@@ -598,7 +598,16 @@ int bcm2835_audio_set_params(bcm2835_als
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if (alsa_stream->chip->cea_chmap >= 0) {
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chmap_value = (unsigned)alsa_stream->chip->cea_chmap << 24;
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} else {
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- chmap_value = 0; /* force stereo */
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+ /* fallback layouts for applications which do not use chmap API */
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+ chmap_value = 0x00;
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+ switch (channels) {
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+ case 3: chmap_value = 0x01; break;
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+ case 4: chmap_value = 0x03; break;
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+ case 5: chmap_value = 0x07; break;
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+ case 6: chmap_value = 0x0b; break;
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+ case 7: chmap_value = 0x0f; break;
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+ case 8: chmap_value = 0x13; break;
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+ }
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for (i = 0; i < 8; i++)
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alsa_stream->chip->map_channels[i] = i;
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}
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