* [PATCH 2/2] ALSA: usb-audio: clean up presonus s1810 consts
2026-01-11 0:00 [PATCH 0/2] ALSA: usb-audio: presonus s1810 minor cleanup and document fenugrec via B4 Relay
2026-01-11 0:00 ` [PATCH 1/2] ALSA: usb-audio: presonus s18xx uses little-endian fenugrec via B4 Relay
@ 2026-01-11 0:00 ` fenugrec via B4 Relay
2026-01-11 14:13 ` kernel test robot
1 sibling, 1 reply; 4+ messages in thread
From: fenugrec via B4 Relay @ 2026-01-11 0:00 UTC (permalink / raw)
To: Takashi Iwai; +Cc: linux-sound, linux-kernel, roy.vegard.ovesen, fenugrec
From: fenugrec <fenugrec@mail.com>
- Reorder some #define blocks
- Document mixer/volume levels
- Document some Ctl request fields (tag, len)
- replace some magic numbers with macros
No functional change intended. The information is based on reverse
engineering.
Signed-off-by: fenugrec <fenugrec@mail.com>
---
sound/usb/mixer_s1810c.c | 204 ++++++++++++++++++++++++++++-------------------
1 file changed, 124 insertions(+), 80 deletions(-)
diff --git a/sound/usb/mixer_s1810c.c b/sound/usb/mixer_s1810c.c
index fd9b4d11c7b2..9e9e2f2b6336 100644
--- a/sound/usb/mixer_s1810c.c
+++ b/sound/usb/mixer_s1810c.c
@@ -25,12 +25,6 @@
#include "helper.h"
#include "mixer_s1810c.h"
-#define SC1810C_CMD_REQ 160
-#define SC1810C_CMD_REQTYPE \
- (USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT)
-#define SC1810C_CMD_F1 0x50617269
-#define SC1810C_CMD_F2 0x14
-
/*
* DISCLAIMER: These are just guesses based on the
* dumps I got.
@@ -42,9 +36,8 @@
* * b selects an input channel (see below).
* * c selects an output channel pair (see below).
* * d selects left (0) or right (1) of that pair.
- * * e 0-> disconnect, 0x01000000-> connect,
- * 0x0109-> used for stereo-linking channels,
- * e is also used for setting volume levels
+ * * e level : see MIXER_LEVEL_* defines below.
+ * Also used for setting volume levels
* in which case b is also set so I guess
* this way it is possible to set the volume
* level from the specified input to the
@@ -75,52 +68,98 @@
* For output (0x65):
* * b is the output channel (see above).
* * c is zero.
- * * e I guess the same as with mixer except 0x0109
- * which I didn't see in my dumps.
+ * * e I guess the same as with mixer
+ *
+ */
+/** struct s1810c_ctl_packet - basic vendor request
+ * @selector: device/mixer/output
+ * @b: request-dependant field b
+ * @tag: fixed value identifying type of request
+ * @len: sizeof this struct - 8 (excludes first 2 fields)
+ * i.e. for basic struct s1810c_ctl_packet: len is 5*4=0x14
+ * @c: request-dependant field c
+ * @d: request-dependant field d
+ * @e: request-dependant field e
*
- * The two fixed fields have the same values for
- * mixer and output but a different set for device.
+ * See longer description above. This could be combined
+ * (as a union?) with the longer struct s1810c_state_packet
*/
struct s1810c_ctl_packet {
- __le32 a;
+ __le32 selector;
__le32 b;
- __le32 fixed1;
- __le32 fixed2;
+ __le32 tag;
+ __le32 len;
__le32 c;
__le32 d;
__le32 e;
};
+/** selectors for CMD request
+ */
+#define SC1810C_SEL_DEVICE 0
+#define SC1810C_SEL_MIXER 0x64
+#define SC1810C_SEL_OUTPUT 0x65
+
+
+/** control ids */
#define SC1810C_CTL_LINE_SW 0
#define SC1810C_CTL_MUTE_SW 1
#define SC1824C_CTL_MONO_SW 2
#define SC1810C_CTL_AB_SW 3
#define SC1810C_CTL_48V_SW 4
+/* USB Control (vendor) requests
+ */
+#define SC1810C_CMD_REQ 160
+#define SC1810C_CMD_REQTYPE \
+ (USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT)
+#define SC1810C_CMD_TAG 0x50617269
+#define SC1810C_CMD_LEN 0x14
+
#define SC1810C_SET_STATE_REQ 161
#define SC1810C_SET_STATE_REQTYPE SC1810C_CMD_REQTYPE
-#define SC1810C_SET_STATE_F1 0x64656D73
-#define SC1810C_SET_STATE_F2 0xF4
+#define SC1810C_SET_STATE_TAG 0x64656D73
+#define SC1810C_SET_STATE_LEN 0xF4
#define SC1810C_GET_STATE_REQ 162
#define SC1810C_GET_STATE_REQTYPE \
(USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN)
-#define SC1810C_GET_STATE_F1 SC1810C_SET_STATE_F1
-#define SC1810C_GET_STATE_F2 SC1810C_SET_STATE_F2
-
-#define SC1810C_STATE_F1_IDX 2
-#define SC1810C_STATE_F2_IDX 3
+#define SC1810C_GET_STATE_TAG SC1810C_SET_STATE_TAG
+#define SC1810C_GET_STATE_LEN SC1810C_SET_STATE_LEN
+
+/** Mixer levels normally range from 0 (off) to 0x0100 0000 (0 dB).
+ * raw_level = 2^24 * 10^(db_level / 20), thus
+ * -3dB = 0xb53bf0 (technically, half-power -3.01...dB would be 0xb504f3)
+ * -96dB = 0x109
+ * -99dB = 0xBC
+ * PC software sliders cover -96 to +10dB (0x0329 8b08),
+ * but the value 0 (-inf dB) can be used when e.g. Mixer Bypass is enabled.
+ * Unclear what the hardware's maximum value is.
+ *
+ * Note, when a channel is panned to two channels (stereo),
+ * the mixer level is set to slider value (by default -96dB) minus 3dB,
+ * which explains the -99dB value seen in USB captures.
+ */
+#define MIXER_LEVEL_MUTE 0
+#define MIXER_LEVEL_N99DB 0xbc
+#define MIXER_LEVEL_N3DB 0xb53bf0
+#define MIXER_LEVEL_0DB 0x1000000
-/*
+/**
* This packet includes mixer volumes and
* various other fields, it's an extended
* version of ctl_packet, with a and b
- * being zero and different f1/f2.
+ * being zero and different tag/length.
*/
struct s1810c_state_packet {
__le32 fields[63];
};
+/** indices into s1810c_state_packet.fields[]
+ */
+#define SC1810C_STATE_TAG_IDX 2
+#define SC1810C_STATE_LEN_IDX 3
+
#define SC1810C_STATE_48V_SW 58
#define SC1810C_STATE_LINE_SW 59
#define SC1810C_STATE_MUTE_SW 60
@@ -134,16 +173,16 @@ struct s1810_mixer_state {
};
static int
-snd_s1810c_send_ctl_packet(struct usb_device *dev, u32 a,
+snd_s1810c_send_ctl_packet(struct usb_device *dev, u32 sel,
u32 b, u32 c, u32 d, u32 e)
{
struct s1810c_ctl_packet pkt = { 0 };
int ret = 0;
- pkt.fixed1 = SC1810C_CMD_F1;
- pkt.fixed2 = SC1810C_CMD_F2;
+ pkt.tag = SC1810C_CMD_TAG;
+ pkt.len = SC1810C_CMD_LEN;
- pkt.a = __cpu_to_le32(a);
+ pkt.selector = __cpu_to_le32(sel);
pkt.b = __cpu_to_le32(b);
pkt.c = __cpu_to_le32(c);
pkt.d = __cpu_to_le32(d);
@@ -176,8 +215,8 @@ snd_sc1810c_get_status_field(struct usb_device *dev,
struct s1810c_state_packet pkt_in = { { 0 } };
int ret = 0;
- pkt_out.fields[SC1810C_STATE_F1_IDX] = __cpu_to_le32(SC1810C_SET_STATE_F1);
- pkt_out.fields[SC1810C_STATE_F2_IDX] = __cpu_to_le32(SC1810C_SET_STATE_F2);
+ pkt_out.fields[SC1810C_STATE_TAG_IDX] = __cpu_to_le32(SC1810C_SET_STATE_TAG);
+ pkt_out.fields[SC1810C_STATE_LEN_IDX] = __cpu_to_le32(SC1810C_SET_STATE_LEN);
ret = snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0),
SC1810C_SET_STATE_REQ,
SC1810C_SET_STATE_REQTYPE,
@@ -216,8 +255,8 @@ static int snd_s1810c_init_mixer_maps(struct snd_usb_audio *chip)
switch (chip->usb_id) {
case USB_ID(0x194f, 0x010c): /* 1810c */
/* Set initial volume levels ? */
- a = 0x64;
- e = 0xbc;
+ a = SC1810C_SEL_MIXER;
+ e = MIXER_LEVEL_N99DB;
for (n = 0; n < 2; n++) {
off = n * 18;
for (b = off; b < 18 + off; b++) {
@@ -234,22 +273,21 @@ static int snd_s1810c_init_mixer_maps(struct snd_usb_audio *chip)
* I noticed on UC that DAW channels have different
* initial volumes, so this makes sense.
*/
- e = 0xb53bf0;
+ e = MIXER_LEVEL_N3DB;
}
/* Connect analog outputs ? */
- a = 0x65;
- e = 0x01000000;
+ a = SC1810C_SEL_OUTPUT;
for (b = 1; b < 3; b++) {
- snd_s1810c_send_ctl_packet(dev, a, b, 0, 0, e);
- snd_s1810c_send_ctl_packet(dev, a, b, 0, 1, e);
+ snd_s1810c_send_ctl_packet(dev, a, b, 0, 0, MIXER_LEVEL_0DB);
+ snd_s1810c_send_ctl_packet(dev, a, b, 0, 1, MIXER_LEVEL_0DB);
}
- snd_s1810c_send_ctl_packet(dev, a, 0, 0, 0, e);
- snd_s1810c_send_ctl_packet(dev, a, 0, 0, 1, e);
+ snd_s1810c_send_ctl_packet(dev, a, 0, 0, 0, MIXER_LEVEL_0DB);
+ snd_s1810c_send_ctl_packet(dev, a, 0, 0, 1, MIXER_LEVEL_0DB);
/* Set initial volume levels for S/PDIF mappings ? */
- a = 0x64;
- e = 0xbc;
+ a = SC1810C_SEL_MIXER;
+ e = MIXER_LEVEL_N99DB;
c = 3;
for (n = 0; n < 2; n++) {
off = n * 18;
@@ -257,26 +295,23 @@ static int snd_s1810c_init_mixer_maps(struct snd_usb_audio *chip)
snd_s1810c_send_ctl_packet(dev, a, b, c, 0, e);
snd_s1810c_send_ctl_packet(dev, a, b, c, 1, e);
}
- e = 0xb53bf0;
+ e = MIXER_LEVEL_N3DB;
}
/* Connect S/PDIF output ? */
- a = 0x65;
- e = 0x01000000;
- snd_s1810c_send_ctl_packet(dev, a, 3, 0, 0, e);
- snd_s1810c_send_ctl_packet(dev, a, 3, 0, 1, e);
+ a = SC1810C_SEL_OUTPUT;
+ snd_s1810c_send_ctl_packet(dev, a, 3, 0, 0, MIXER_LEVEL_0DB);
+ snd_s1810c_send_ctl_packet(dev, a, 3, 0, 1, MIXER_LEVEL_0DB);
/* Connect all outputs (again) ? */
- a = 0x65;
- e = 0x01000000;
+ a = SC1810C_SEL_OUTPUT;
for (b = 0; b < 4; b++) {
- snd_s1810c_send_ctl_packet(dev, a, b, 0, 0, e);
- snd_s1810c_send_ctl_packet(dev, a, b, 0, 1, e);
+ snd_s1810c_send_ctl_packet(dev, a, b, 0, 0, MIXER_LEVEL_0DB);
+ snd_s1810c_send_ctl_packet(dev, a, b, 0, 1, MIXER_LEVEL_0DB);
}
/* Basic routing to get sound out of the device */
- a = 0x64;
- e = 0x01000000;
+ a = SC1810C_SEL_MIXER;
for (c = 0; c < 4; c++) {
for (b = 0; b < 36; b++) {
if ((c == 0 && b == 18) || /* DAW1/2 -> Main */
@@ -284,23 +319,29 @@ static int snd_s1810c_init_mixer_maps(struct snd_usb_audio *chip)
(c == 2 && b == 22) || /* DAW4/5 -> Line5/6 */
(c == 3 && b == 24)) { /* DAW5/6 -> S/PDIF */
/* Left */
- snd_s1810c_send_ctl_packet(dev, a, b, c, 0, e);
- snd_s1810c_send_ctl_packet(dev, a, b, c, 1, 0);
+ snd_s1810c_send_ctl_packet(dev,
+ a, b, c, 0, MIXER_LEVEL_0DB);
+ snd_s1810c_send_ctl_packet(dev,
+ a, b, c, 1, MIXER_LEVEL_MUTE);
b++;
/* Right */
- snd_s1810c_send_ctl_packet(dev, a, b, c, 0, 0);
- snd_s1810c_send_ctl_packet(dev, a, b, c, 1, e);
+ snd_s1810c_send_ctl_packet(dev,
+ a, b, c, 0, MIXER_LEVEL_MUTE);
+ snd_s1810c_send_ctl_packet(dev,
+ a, b, c, 1, MIXER_LEVEL_0DB);
} else {
/* Leave the rest disconnected */
- snd_s1810c_send_ctl_packet(dev, a, b, c, 0, 0);
- snd_s1810c_send_ctl_packet(dev, a, b, c, 1, 0);
+ snd_s1810c_send_ctl_packet(dev,
+ a, b, c, 0, MIXER_LEVEL_MUTE);
+ snd_s1810c_send_ctl_packet(dev,
+ a, b, c, 1, MIXER_LEVEL_MUTE);
}
}
}
/* Set initial volume levels for S/PDIF (again) ? */
- a = 0x64;
- e = 0xbc;
+ a = SC1810C_SEL_MIXER;
+ e = MIXER_LEVEL_N99DB;
c = 3;
for (n = 0; n < 2; n++) {
off = n * 18;
@@ -308,29 +349,26 @@ static int snd_s1810c_init_mixer_maps(struct snd_usb_audio *chip)
snd_s1810c_send_ctl_packet(dev, a, b, c, 0, e);
snd_s1810c_send_ctl_packet(dev, a, b, c, 1, e);
}
- e = 0xb53bf0;
+ e = MIXER_LEVEL_N3DB;
}
/* Connect S/PDIF outputs (again) ? */
- a = 0x65;
- e = 0x01000000;
- snd_s1810c_send_ctl_packet(dev, a, 3, 0, 0, e);
- snd_s1810c_send_ctl_packet(dev, a, 3, 0, 1, e);
+ a = SC1810C_SEL_OUTPUT;
+ snd_s1810c_send_ctl_packet(dev, a, 3, 0, 0, MIXER_LEVEL_0DB);
+ snd_s1810c_send_ctl_packet(dev, a, 3, 0, 1, MIXER_LEVEL_0DB);
/* Again ? */
- snd_s1810c_send_ctl_packet(dev, a, 3, 0, 0, e);
- snd_s1810c_send_ctl_packet(dev, a, 3, 0, 1, e);
+ snd_s1810c_send_ctl_packet(dev, a, 3, 0, 0, MIXER_LEVEL_0DB);
+ snd_s1810c_send_ctl_packet(dev, a, 3, 0, 1, MIXER_LEVEL_0DB);
break;
case USB_ID(0x194f, 0x010d): /* 1824c */
/* Set all output faders to unity gain */
- a = 0x65;
+ a = SC1810C_SEL_OUTPUT;
c = 0x00;
- e = 0x01000000;
-
for (b = 0; b < 9; b++) {
- snd_s1810c_send_ctl_packet(dev, a, b, c, 0, e);
- snd_s1810c_send_ctl_packet(dev, a, b, c, 1, e);
+ snd_s1810c_send_ctl_packet(dev, a, b, c, 0, MIXER_LEVEL_0DB);
+ snd_s1810c_send_ctl_packet(dev, a, b, c, 1, MIXER_LEVEL_0DB);
}
/* Set
@@ -345,7 +383,7 @@ static int snd_s1810c_init_mixer_maps(struct snd_usb_audio *chip)
* Daw 17 -> ADAT out 7, (left) Daw 18 -> ADAT out 8 (right)
* Everything else muted
*/
- a = 0x64;
+ a = SC1810C_SEL_MIXER;
/* The first Daw channel is channel 18 */
left = 18;
@@ -354,14 +392,20 @@ static int snd_s1810c_init_mixer_maps(struct snd_usb_audio *chip)
for (b = 0; b < 36; b++) {
if (b == left) {
- snd_s1810c_send_ctl_packet(dev, a, b, c, 0, 0x01000000);
- snd_s1810c_send_ctl_packet(dev, a, b, c, 1, 0x00);
+ snd_s1810c_send_ctl_packet(dev,
+ a, b, c, 0, MIXER_LEVEL_0DB);
+ snd_s1810c_send_ctl_packet(dev,
+ a, b, c, 1, MIXER_LEVEL_MUTE);
} else if (b == right) {
- snd_s1810c_send_ctl_packet(dev, a, b, c, 0, 0x00);
- snd_s1810c_send_ctl_packet(dev, a, b, c, 1, 0x01000000);
+ snd_s1810c_send_ctl_packet(dev,
+ a, b, c, 0, MIXER_LEVEL_MUTE);
+ snd_s1810c_send_ctl_packet(dev,
+ a, b, c, 1, MIXER_LEVEL_0DB);
} else {
- snd_s1810c_send_ctl_packet(dev, a, b, c, 0, 0x00);
- snd_s1810c_send_ctl_packet(dev, a, b, c, 1, 0x00);
+ snd_s1810c_send_ctl_packet(dev,
+ a, b, c, 0, MIXER_LEVEL_MUTE);
+ snd_s1810c_send_ctl_packet(dev,
+ a, b, c, 1, MIXER_LEVEL_MUTE);
}
}
left += 2;
--
2.52.0
^ permalink raw reply related [flat|nested] 4+ messages in thread