On Wed, 20 Sep 2023 17:16:10 +0200,
Ivan Orlov wrote:
>
> MARIAN Seraph M2 is a fully digital PCI soundcard with 2 MADI inputs
> and outputs. This patch introduces the driver for this soundcard, as
> there is no support for it in the mainline kernel yet.
>
> The original driver was written by Florian Faber in 2012. However, it
> contained multiple issues and couldn't be sent upstream. This patch
> represents the driver which is based on the original version.
>
> The driver works well for all supported rates (from 28 kHz to 108 kHz).
> It supports the non-interleaved access mode only, as it is the only
> access mode allowed by the hardware.
>
> Testing with internal and external loopbacks showed that there is no
> issues with the time synchronization and/or data transmission in the
> driver for all possible rates, so it seems to be production-ready.
>
> Signed-off-by: Ivan Orlov <[email protected]>
> ---
> V1 -> V2:
> - Remove redundant documentation fix
> V2 -> V3:
> - Get rid of useless indirection in the driver code
> - Make the order of includes right
> - Remove redundant defines, including the errorneous 'DEBUG' define
> - Fix the issue with wrong clock modes: the previous version set it
> incorrectly
> - Remove 'speedmode' control - now the driver sets the DCO and VCO modes
> depending on
> the sample rate
> - Remove mHz DCO Rate control - the accuracy of calculation won't allow
> us to set it correctly in mHz anyway
> - Remove the 'detune' control - I can't prove that it works correctly.
> - Extract more numeric constants into defines to make the code more
> comprehendable
> - Remove redundant variables and structure fields
> - Remove the custom silence function, as the PCM middle layer will take
> care of it
> - Remove the custom mmap callback, as the standard PCM mmap would work
> as well
>
> MAINTAINERS | 7 +
> sound/pci/Kconfig | 10 +
> sound/pci/Makefile | 2 +
> sound/pci/marianm2.c | 1399 ++++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 1418 insertions(+)
> create mode 100644 sound/pci/marianm2.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 23e73d19f347..d3413ecc4dfb 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -12622,6 +12622,13 @@ L: [email protected]
> S: Maintained
> F: arch/mips/boot/dts/img/pistachio*
>
> +MARIAN SERAPH M2 SOUND CARD DRIVER
> +M: Ivan Orlov <[email protected]>
> +L: [email protected] (moderated for non-subscribers)
> +S: Maintained
> +F: Documentation/sound/cards/marian-m2.rst
> +F: sound/pci/marianm2.c
> +
> MARVELL 88E6XXX ETHERNET SWITCH FABRIC DRIVER
> M: Andrew Lunn <[email protected]>
> L: [email protected]
> diff --git a/sound/pci/Kconfig b/sound/pci/Kconfig
> index 787868c9e91b..e3dad79743e5 100644
> --- a/sound/pci/Kconfig
> +++ b/sound/pci/Kconfig
> @@ -222,6 +222,16 @@ config SND_CMIPCI
> To compile this driver as a module, choose M here: the module
> will be called snd-cmipci.
>
> +config SND_MARIANM2
> + tristate "MARIAN Seraph M2"
> + select SND_PCM
> + help
> + Say Y to include support for MARIAN Seraph M2 sound card
> + <file:Documentation/sound/cards/marian-m2.rst>.
> +
> + To compile this driver as a module, choose M here: the module
> + will be called snd-marianm2
> +
> config SND_OXYGEN_LIB
> tristate
>
> diff --git a/sound/pci/Makefile b/sound/pci/Makefile
> index 04cac7469139..4d2f52c98a74 100644
> --- a/sound/pci/Makefile
> +++ b/sound/pci/Makefile
> @@ -22,6 +22,7 @@ snd-fm801-objs := fm801.o
> snd-intel8x0-objs := intel8x0.o
> snd-intel8x0m-objs := intel8x0m.o
> snd-maestro3-objs := maestro3.o
> +snd-marianm2-objs := marianm2.o
> snd-rme32-objs := rme32.o
> snd-rme96-objs := rme96.o
> snd-sis7019-objs := sis7019.o
> @@ -48,6 +49,7 @@ obj-$(CONFIG_SND_FM801) += snd-fm801.o
> obj-$(CONFIG_SND_INTEL8X0) += snd-intel8x0.o
> obj-$(CONFIG_SND_INTEL8X0M) += snd-intel8x0m.o
> obj-$(CONFIG_SND_MAESTRO3) += snd-maestro3.o
> +obj-$(CONFIG_SND_MARIANM2) += snd-marianm2.o
> obj-$(CONFIG_SND_RME32) += snd-rme32.o
> obj-$(CONFIG_SND_RME96) += snd-rme96.o
> obj-$(CONFIG_SND_SIS7019) += snd-sis7019.o
> diff --git a/sound/pci/marianm2.c b/sound/pci/marianm2.c
> new file mode 100644
> index 000000000000..7f0135ef3202
> --- /dev/null
> +++ b/sound/pci/marianm2.c
> @@ -0,0 +1,1399 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * ALSA driver for MARIAN Seraph audio interfaces
> + *
> + * Copyright (c) 2012 Florian Faber <[email protected]>,
> + * 2023 Ivan Orlov <[email protected]>
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/module.h>
> +#include <linux/pci.h>
> +#include <linux/interrupt.h>
> +#include <sound/core.h>
> +#include <sound/control.h>
> +#include <sound/pcm.h>
> +#include <sound/pcm_params.h>
> +#include <sound/core.h>
> +#include <sound/pcm.h>
> +#include <sound/initval.h>
> +#include <sound/info.h>
> +
> +#define M2_CHANNELS_COUNT 128
> +
> +#define M2_SPEEDMODE 2
> +
> +#define M2_FRAME_SIZE (M2_CHANNELS_COUNT * 4)
> +#define SUBSTREAM_PERIOD_SIZE (2048 * M2_FRAME_SIZE)
> +#define SUBSTREAM_BUF_SIZE (2 * SUBSTREAM_PERIOD_SIZE)
> +#define M2_DMA_BUFSIZE (SUBSTREAM_BUF_SIZE * 2)
> +
> +#define SERAPH_RD_IRQ_STATUS 0x00
> +#define SERAPH_RD_HWPOINTER 0x8C
> +
> +#define SERAPH_WR_DMA_ADR 0x04
> +#define SERAPH_WR_DMA_BLOCKS 0x10
> +
> +#define M2_DISABLE_PLAY_IRQ BIT(1)
> +#define M2_DISABLE_CAPT_IRQ BIT(2)
> +#define M2_ENABLE_LOOPBACK BIT(3)
> +#define SERAPH_WR_DMA_ENABLE 0x84
> +#define SERAPH_WR_IE_ENABLE 0xAC
> +
> +#define PCI_VENDOR_ID_MARIAN 0x1382
> +#define PCI_DEVICE_ID_MARIAN_SERAPH_M2 0x5021
> +
> +#define RATE_SLOW 54000
> +
> +#define FREQ_MIN 28000
> +#define FREQ_MAX 108000
> +
> +#define SPEEDMODE_SLOW 1
> +#define SPEEDMODE_FAST 2
> +
> +#define MARIAN_PORTS_TYPE_INPUT 0
> +#define MARIAN_PORTS_TYPE_OUTPUT 1
> +
> +#define MARIAN_SPI_CLOCK_DIVIDER 0x74
> +
> +#define WCLOCK_NEW_VAL BIT(31)
> +#define SPI_ALL_READY BIT(31)
> +
> +#define M2_CLOCK_SRC_DCO 1
> +#define M2_CLOCK_SRC_SYNCBUS 2
> +#define M2_CLOCK_SRC_MADI1 4
> +#define M2_CLOCK_SRC_MADI2 5
> +
> +#define M2_INP1_SYNC_CTL_ID 0
> +#define M2_INP1_CM_CTL_ID 0
> +#define M2_INP1_FM_CTL_ID 0
> +#define M2_INP1_FREQ_CTL_ID 4
> +#define M2_OUT1_CM_CTL_ID 0
> +#define M2_OUT1_FM_CTL_ID 0
> +#define M2_INP2_SYNC_CTL_ID 1
> +#define M2_INP2_CM_CTL_ID 1
> +#define M2_INP2_FM_CTL_ID 1
> +#define M2_INP2_FREQ_CTL_ID 5
> +#define M2_OUT2_CM_CTL_ID 1
> +#define M2_OUT2_FM_CTL_ID 1
> +
> +#define M2_SPI_STATE 0x70
> +#define M2_SPI_RESET 0x70
> +#define M2_SPI_CHIP_SELECT 0x60
> +#define M2_SPI_BITS_TO_WRITE 0x64
> +#define M2_SPI_BITS_TO_READ 0x68
> +#define M2_SPI_WRITE_DATA 0x6C
> +#define M2_SPI_DELAY 100
> +
> +#define M2_CLOCK_SRC_SELECT 0xC8
> +#define M2_WORD_CLOCK_REG 0x94
> +
> +#define M2_SET_DCO 0x88
> +
> +#define M2_VCO_CLOCK_RANGE 0x8C
> +#define M2_CLOCK_MODE 0x80
> +
> +#define M2_SET_CLOCK_SRC 0x90
> +
> +// MADI FPGA register 0x41
> +// Enable both MADI transmitters (=1)
> +#define M2_TX_ENABLE 0
> +// Use int (=0) or 32bit IEEE float (=1)
> +#define M2_INT_FLOAT 4
> +// Big endian (=0), little endian (=1)
> +#define M2_ENDIANNESS 5
> +// MSB first (=0), LSB first (=1)
> +#define M2_BIT_ORDER 6
> +
> +// MADI FPGA register 0x42
> +// Send 56ch (=0) or 64ch (=1) MADI frames
> +#define M2_PORT1_MODE 0
> +// Send 48kHz (=0) or 96kHz (=1) MADI frames
> +#define M2_PORT1_FRAME 1
> +// Send 56ch (=0) or 64ch (=1) MADI frames
> +#define M2_PORT2_MODE 2
> +// Send 48kHz (=0) or 96kHz (=1) MADI frames
> +#define M2_PORT2_FRAME 3
> +
> +#define M2_CARD_NAME "Seraph M2"
> +
> +struct marian_card {
> + struct snd_pcm_substream *playback_substream;
> + struct snd_pcm_substream *capture_substream;
> +
> + struct snd_card *card;
> + struct snd_pcm *pcm;
> + struct snd_dma_buffer dmabuf;
> +
> + struct snd_dma_buffer playback_buf;
> + struct snd_dma_buffer capture_buf;
> +
> + struct pci_dev *pci;
> + unsigned long port;
> + void __iomem *iobase;
> + int irq;
> +
> + unsigned int idx;
> +
> + /* hardware registers lock */
> + spinlock_t reglock;
> +
> + /* spinlock for SPI communication */
> + spinlock_t spi_lock;
> +
> + /* mutex for frequency measurement */
> + struct mutex freq_mutex;
> +
> + /* Enables or disables hardware loopback */
> + int loopback;
> +
> + /* 0..15, meaning depending on the card type */
> + unsigned int clock_source;
> +
> + /* Frequency of the internal oscillator (Hertz) */
> + unsigned int dco;
> +
> + /* Clock settings mask */
> + u8 shadow_40;
> +
> + /* TX enable/disable mask */
> + u8 shadow_41;
> +
> + /* Port mode mask */
> + u8 shadow_42;
> +
> + /* Frame mode mask */
> + u8 frame;
> +};
> +
> +enum CLOCK_SOURCE {
> + CLOCK_SRC_INTERNAL = 0,
> + CLOCK_SRC_SYNCBUS = 1,
> + CLOCK_SRC_INP1 = 2,
> + CLOCK_SRC_INP2 = 3,
> +};
> +
> +enum m2_num_mode {
> + M2_NUM_MODE_INT = 0,
> + M2_NUM_MODE_FLOAT = 1,
> +};
> +
> +enum m2_endianness_mode {
> + M2_BE = 0,
> + M2_LE = 1,
> +};
> +
> +static const struct pci_device_id snd_marian_ids[] = {
> + {PCI_DEVICE(PCI_VENDOR_ID_MARIAN, PCI_DEVICE_ID_MARIAN_SERAPH_M2), 0, 0, 6},
> + { }
> +};
> +
> +MODULE_DEVICE_TABLE(pci, snd_marian_ids);
> +
> +static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX; // Index 0-MAX
> +static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR; // ID for this card
> +
> +module_param_array(index, int, NULL, 0444);
> +MODULE_PARM_DESC(index, "Index value for MARIAN PCI soundcard");
> +module_param_array(id, charp, NULL, 0444);
> +MODULE_PARM_DESC(id, "ID string for MARIAN PCI soundcard");
> +
> +static int spi_wait_for_ar(struct marian_card *marian)
> +{
> + int tries = 10;
> +
> + while (tries > 0) {
> + if (ioread32(marian->iobase + M2_SPI_STATE) == SPI_ALL_READY)
> + break;
> + udelay(M2_SPI_DELAY);
> + tries--;
> + }
> + if (tries == 0)
> + return -EIO;
> + return 0;
> +}
> +
> +static int marian_spi_transfer(struct marian_card *marian, uint16_t cs, uint16_t bits_write,
> + u8 *data_write, uint16_t bits_read, u8 *data_read)
> +{
> + u32 buf = 0;
> + unsigned int i;
> + int err = 0;
> +
> + spin_lock(&marian->spi_lock);
> +
> + if (spi_wait_for_ar(marian) < 0)
> + iowrite32(0x1234, marian->iobase + M2_SPI_RESET); // Resetting SPI bus
> +
> + iowrite32(cs, marian->iobase + M2_SPI_CHIP_SELECT);
> + iowrite32(bits_write, marian->iobase + M2_SPI_BITS_TO_WRITE);
> + iowrite32(bits_read, marian->iobase + M2_SPI_BITS_TO_READ);
> +
> + if (bits_write <= 32) {
> + // left-align data
> + if (bits_write <= 8)
> + buf = data_write[0] << (32 - bits_write);
> + else if (bits_write <= 16)
> + buf = data_write[0] << 24 | data_write[1] << (32 - bits_write);
> +
> + iowrite32(buf, marian->iobase + M2_SPI_WRITE_DATA);
> + }
> + if (bits_read > 0 && bits_read <= 32) {
> + if (spi_wait_for_ar(marian) < 0) {
> + dev_dbg(marian->card->dev,
> + "Bus didn't signal AR\n");
> + err = -EIO;
> + goto unlock_exit;
> + }
> +
> + buf = ioread32(marian->iobase + MARIAN_SPI_CLOCK_DIVIDER);
> +
> + buf <<= 32 - bits_read;
> + i = 0;
> +
> + while (bits_read > 0) {
> + data_read[i++] = (buf >> 24) & 0xFF;
> + buf <<= 8;
> + bits_read -= 8;
> + }
> + }
> +
> +unlock_exit:
> + spin_unlock(&marian->spi_lock);
> + return err;
> +}
> +
> +static u8 marian_m2_spi_read(struct marian_card *marian, u8 adr)
> +{
> + u8 buf_in;
> +
> + adr = adr & 0x7F;
> +
> + if (marian_spi_transfer(marian, 0x02, 8, &adr, 8, &buf_in) == 0)
> + return buf_in;
> +
> + return 0;
> +}
> +
> +static int marian_m2_spi_write(struct marian_card *marian, u8 adr, u8 val)
> +{
> + u8 buf_out[2];
> +
> + buf_out[0] = 0x80 | adr;
> + buf_out[1] = val;
> +
> + return marian_spi_transfer(marian, 0x02, 16, (u8 *)&buf_out, 0, NULL);
> +}
> +
> +/*
> + * Measure the frequency of a clock source.
> + * The measurement is triggered and the FPGA's ready
> + * signal polled (normally takes up to 2ms). The measurement
> + * has only a certainty of 10-20Hz, this function rounds it up
> + * to the nearest 10Hz step (in 1FS).
> + */
> +static unsigned int marian_measure_freq(struct marian_card *marian, unsigned int source)
> +{
> + u32 val;
> + int tries = 5;
> +
> + mutex_lock(&marian->freq_mutex);
> + iowrite32(source, marian->iobase + M2_CLOCK_SRC_SELECT);
> +
> + mdelay(2);
> +
> + while (tries > 0) {
> + val = ioread32(marian->iobase + M2_WORD_CLOCK_REG);
> + if (val & WCLOCK_NEW_VAL)
> + break;
> +
> + mdelay(1);
> + tries--;
> + }
> +
> + mutex_unlock(&marian->freq_mutex);
> +
> + if (tries > 0)
> + return (((1280000000 / ((val & 0x3FFFF) + 1)) + 5 * M2_SPEEDMODE)
> + / (10 * M2_SPEEDMODE)) * 10;
> +
> + return 0;
> +}
> +
> +static int marian_generic_frequency_info(struct snd_kcontrol *kcontrol,
> + struct snd_ctl_elem_info *uinfo)
> +{
> + uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
> + uinfo->count = 1;
> + uinfo->value.integer.min = FREQ_MIN;
> + uinfo->value.integer.max = FREQ_MAX;
> + uinfo->value.integer.step = 1;
> + return 0;
> +}
> +
> +static int marian_generic_frequency_get(struct snd_kcontrol *kcontrol,
> + struct snd_ctl_elem_value *ucontrol)
> +{
> + struct marian_card *marian = snd_kcontrol_chip(kcontrol);
> +
> + ucontrol->value.integer.value[0] = marian_measure_freq(marian, kcontrol->private_value);
> + return 0;
> +}
> +
> +static int marian_generic_frequency_create(struct marian_card *marian, char *label, u32 idx)
> +{
> + struct snd_kcontrol_new c = {
> + .iface = SNDRV_CTL_ELEM_IFACE_MIXER,
> + .name = label,
> + .private_value = idx,
> + .access = SNDRV_CTL_ELEM_ACCESS_READ | SNDRV_CTL_ELEM_ACCESS_VOLATILE,
> + .info = marian_generic_frequency_info,
> + .get = marian_generic_frequency_get
> + };
> +
> + return snd_ctl_add(marian->card, snd_ctl_new1(&c, marian));
> +}
> +
> +static void marian_generic_set_dco(struct marian_card *marian, unsigned int freq)
> +{
> + u64 val;
> +
> + val = freq;
> + val <<= 36;
> + val /= 80000000;
> +
> + iowrite32((u32)val, marian->iobase + M2_SET_DCO);
> +
> + marian->dco = freq;
> +}
> +
> +static int marian_generic_dco_int_info(struct snd_kcontrol *kcontrol,
> + struct snd_ctl_elem_info *uinfo)
> +{
> + uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
> + uinfo->count = 1;
> + uinfo->value.integer.min = FREQ_MIN;
> + uinfo->value.integer.max = FREQ_MAX;
> + uinfo->value.integer.step = 1;
> + return 0;
> +}
> +
> +static int marian_generic_dco_int_get(struct snd_kcontrol *kcontrol,
> + struct snd_ctl_elem_value *ucontrol)
> +{
> + struct marian_card *marian = snd_kcontrol_chip(kcontrol);
> +
> + ucontrol->value.integer.value[0] = marian->dco;
> +
> + return 0;
> +}
> +
> +static int marian_generic_dco_int_put(struct snd_kcontrol *kcontrol,
> + struct snd_ctl_elem_value *ucontrol)
> +{
> + struct marian_card *marian = snd_kcontrol_chip(kcontrol);
> +
> + spin_lock(&marian->reglock);
> + marian_generic_set_dco(marian, ucontrol->value.integer.value[0]);
> + spin_unlock(&marian->reglock);
The control get/put callbacks can sleep, hence usually it's
spin_lock_irq(). Or if the all places for this lock are sleepable
context, use a mutex instead.
> +static int marian_control_pcm_loopback_info(struct snd_kcontrol *kcontrol,
> + struct snd_ctl_elem_info *uinfo)
> +{
> + uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
> + uinfo->count = 1;
> + uinfo->value.integer.min = 0;
> + uinfo->value.integer.max = 1;
> +
> + return 0;
This can be replaced with snd_ctl_boolean_mono_info.
> +}
> +
> +static int marian_control_pcm_loopback_get(struct snd_kcontrol *kcontrol,
> + struct snd_ctl_elem_value *ucontrol)
> +{
> + struct marian_card *marian = snd_kcontrol_chip(kcontrol);
> +
> + ucontrol->value.integer.value[0] = marian->loopback;
> +
> + return 0;
> +}
> +
> +static int marian_control_pcm_loopback_put(struct snd_kcontrol *kcontrol,
> + struct snd_ctl_elem_value *ucontrol)
> +{
> + struct marian_card *marian = snd_kcontrol_chip(kcontrol);
> +
> + marian->loopback = ucontrol->value.integer.value[0];
Better to normalize with !!ucontrol->value.integer.value[0].
The value check isn't done as default.
> +static int marian_control_pcm_loopback_create(struct marian_card *marian)
> +{
> + struct snd_kcontrol_new c = {
> + .iface = SNDRV_CTL_ELEM_IFACE_PCM,
> + .name = "Loopback",
Better to have "Switch" suffix.
> +static int marian_m2_output_frame_mode_create(struct marian_card *marian, char *label, u32 idx)
> +{
> + struct snd_kcontrol_new c = {
> + .iface = SNDRV_CTL_ELEM_IFACE_MIXER,
> + .name = label,
> + .private_value = idx,
> + .access = SNDRV_CTL_ELEM_ACCESS_READWRITE | SNDRV_CTL_ELEM_ACCESS_VOLATILE,
Does this have to be VOLATILE? Some others look also dubious.
Basically you set the value via this mixer element, then it's
persistent.
thanks,
Takashi
On 9/20/23 19:55, Takashi Iwai wrote:
>> + spin_lock(&marian->reglock);
>> + marian_generic_set_dco(marian, ucontrol->value.integer.value[0]);
>> + spin_unlock(&marian->reglock);
>
> The control get/put callbacks can sleep, hence usually it's
> spin_lock_irq(). Or if the all places for this lock are sleepable
> context, use a mutex instead.
>
Alright, it looks like reglock is used in sleepable context only, so
I'll replace it with mutex. Thanks!
>> +static int marian_control_pcm_loopback_info(struct snd_kcontrol *kcontrol,
>> + struct snd_ctl_elem_info *uinfo)
>> +{
>> + uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
>> + uinfo->count = 1;
>> + uinfo->value.integer.min = 0;
>> + uinfo->value.integer.max = 1;
>> +
>> + return 0;
>
> This can be replaced with snd_ctl_boolean_mono_info.
>
>
Oh, I forgot to use 'snd_ctl_boolean_mono_info' here. Will be done.
>> +}
>> +
>> +static int marian_control_pcm_loopback_get(struct snd_kcontrol *kcontrol,
>> + struct snd_ctl_elem_value *ucontrol)
>> +{
>> + struct marian_card *marian = snd_kcontrol_chip(kcontrol);
>> +
>> + ucontrol->value.integer.value[0] = marian->loopback;
>> +
>> + return 0;
>> +}
>> +
>> +static int marian_control_pcm_loopback_put(struct snd_kcontrol *kcontrol,
>> + struct snd_ctl_elem_value *ucontrol)
>> +{
>> + struct marian_card *marian = snd_kcontrol_chip(kcontrol);
>> +
>> + marian->loopback = ucontrol->value.integer.value[0];
>
> Better to normalize with !!ucontrol->value.integer.value[0].
> The value check isn't done as default.
>
Will be fixed, thanks!
>> +static int marian_control_pcm_loopback_create(struct marian_card *marian)
>> +{
>> + struct snd_kcontrol_new c = {
>> + .iface = SNDRV_CTL_ELEM_IFACE_PCM,
>> + .name = "Loopback",
>
> Better to have "Switch" suffix.
>
Yeah, and I guess some other controls also have to be renamed. Will be
done :)
>> +static int marian_m2_output_frame_mode_create(struct marian_card *marian, char *label, u32 idx)
>> +{
>> + struct snd_kcontrol_new c = {
>> + .iface = SNDRV_CTL_ELEM_IFACE_MIXER,
>> + .name = label,
>> + .private_value = idx,
>> + .access = SNDRV_CTL_ELEM_ACCESS_READWRITE | SNDRV_CTL_ELEM_ACCESS_VOLATILE,
>
> Does this have to be VOLATILE? Some others look also dubious.
> Basically you set the value via this mixer element, then it's
> persistent.
>
As I understand, some controls which depend on external inputs (like the
'Input 1 Freq', which measures frequency on the Input 1), should be
volatile, right?
This one definitely shouldn't, so I will change it to persistent.
Thank you for your prompt reply and review!
--
Kind regards,
Ivan Orlov
>
> thanks,
>
> Takashi