Re: Patch for AICA sound support on SEGA Dreamcast

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At Mon, 03 Apr 2006 15:45:22 +0100,
Adrian McMenamin wrote:
> 
> This provides ALSA sound for the Sega Dreamcast. Seems to work well for
> me, but there is a dearth of testers.
> 
> Signed off by Adrian McMenamin ([email protected])

Thanks for the patch.  Some comments are below.

> diff -ruN /home/adrian/alsa-old/alsa-driver/sh/aica.h /home/adrian/alsa-driver/sh/aica.h
> --- /home/adrian/alsa-old/alsa-driver/sh/aica.h	1970-01-01 01:00:00.000000000 +0100
> +++ /home/adrian/alsa-driver/sh/aica.h	2006-04-03 15:40:07.000000000 +0100
> @@ -0,0 +1,79 @@
(snip)
> +typedef struct {
> +	snd_card_t *card;
> +	snd_pcm_substream_t *substream;
> +	int clicks;
> +	int current_period;
> +	struct timer_list timer;
> +	int master_volume;
> +
> +} snd_card_aica_t;

Please avoid use of typedefs as much as possible.
We (finally :-) got rid of whole typedefs recently from the ALSA core
code.


> +typedef struct aica_channel {
> +	uint32_t cmd;		/* Command ID           */
> +	uint32_t pos;		/* Sample position      */
> +	uint32_t length;	/* Sample length        */
> +	uint32_t freq;		/* Frequency            */
> +	uint32_t vol;		/* Volume 0-255         */
> +	uint32_t pan;		/* Pan 0-255            */
> +	uint32_t sfmt;		/* Sound format         */
> +	uint32_t flags;		/* Bit flags            */
> +} aica_channel_t;

Ditto.


> diff -ruN /home/adrian/alsa-old/alsa-driver/sh/snd_aica.c /home/adrian/alsa-driver/sh/snd_aica.c
> --- /home/adrian/alsa-old/alsa-driver/sh/snd_aica.c	1970-01-01 01:00:00.000000000 +0100
> +++ /home/adrian/alsa-driver/sh/snd_aica.c	2006-04-03 15:40:20.000000000 +0100
> @@ -0,0 +1,802 @@
(snip)
> +
> +static int index = 0;

No need for explicit zero initialization.

> +static char *id = "0";

You should set it to NULL, i.e. don't set value here.

> +static int enable= 1;
> 
> +module_param(index, int, 0444);
> +MODULE_PARM_DESC(index, "Index value for " CARD_NAME " soundcard.");
> +module_param(id, charp, 0444);
> +MODULE_PARM_DESC(id, "ID string for " CARD_NAME " soundcard.");
> +module_param(enable, bool, 0644);
> +MODULE_PARM_DESC(enable, "Enable " CARD_NAME " soundcard.");
> +
> +
> +/* SPU specific functions */
> +
> +inline void spu_write_wait()

Lack of static.  And lack of (void) argument.


> +{
> +	while (1) {
> +		if (!(readl(G2_FIFO) & 0x11))
> +			break;
> +	}

Safer to have a timeout?

> +
> +	return;
> +}
> +
> +
> +
> +static void spu_memset(uint32_t toi, unsigned long what, int length)

The type of second argument should be "void __iomem *" for accessing
readl/writel.


> +{
> +	uint32_t *to = (uint32_t *) (SPU_MEMORY_BASE + toi);
> +	int i;
> +
> +	if (length % 4)
> +		length = (length / 4) + 1;
> +	else
> +		length = length / 4;

Shouldn't be always aligned to 4?  Something like

	snd_assert(length % 4 == 0, return);

> +	spu_write_wait();
> +	for (i = 0; i < length; i++) {
> +		writel(what, to);
> +		to++;
> +		if (i && !(i % 8))
> +			spu_write_wait();
> +	}
> +	return;
> +}
> +
> +static void spu_memload(uint32_t toi, uint8_t * from, int length)

Also "uint8_t __iomem *from" (maybe a "void __iomem *" would be
simpler since you can avoid an explicit cast below).

Also, these lowlevel functions look racy.  Many places call
spu_memload() without a proper lock.

> +{
> +	uint32_t *froml = (uint32_t *) from;
> +	uint32_t *to = (uint32_t *) (SPU_MEMORY_BASE + toi);

Should be "uint32_t __iomem *".

> +	int i, val;
> +	if (length % 4)
> +		length = (length / 4) + 1;
> +	else
> +		length = length / 4;

Similar as spu_memset().

> +	spu_write_wait();
> +	for (i = 0; i < length; i++) {
> +		val = *froml;
> +		writel(val, to);
> +		froml++;
> +		to++;
> +		if (i && !(i % 8))
> +			spu_write_wait();
> +	}
> +	return;
> +
> +}
> +
> +static void spu_disable()

Need (void) for empty argument.

> +{
> +	int i;
> +	uint32_t regval;
> +	spu_write_wait();
> +	regval = readl(ARM_RESET_REGISTER);

readl and writel take void __iomem *.

> +	regval |= 1;
> +	spu_write_wait();
> +	writel(regval, ARM_RESET_REGISTER);
> +	for (i = 0; i < 64; i++) {
> +		spu_write_wait();
> +		regval = readl(SPU_REGISTER_BASE + (i * 0x80));
> +		regval = (regval & ~0x4000) | 0x8000;
> +		spu_write_wait();
> +		writel(regval, SPU_REGISTER_BASE + (i * 0x80));
> +
> +	}
> +
> +}
> +
> +
> +static void spu_enable()

Lack of (void)....  in many others below, too.

> +{
> +	uint32_t regval = readl(ARM_RESET_REGISTER);
> +	regval &= ~1;
> +	spu_write_wait();
> +	writel(regval, ARM_RESET_REGISTER);
> +	return;
> +
> +}
> +
> +
> +/* Halt the sound processor,
> +   clear the memory,
> +   load some default ARM7 code,
> +   and then restart ARM7
> +*/
> +static int spu_init()
> +{
> +
> +	spu_disable();
> +	spu_memset(0, 0, 0x200000 / 4);
> +	*(uint32_t *) SPU_MEMORY_BASE = 0xea000002;

Is it a right code?

> +	spu_enable();
> +	schedule();
> +	return 0;
> +}
> +
> +
> +
> +static aica_channel_t *channel;

Better to assign this to runtime->private_data instead of a static
record.

> +inline static void aica_chn_start()
> +{
> +	spu_write_wait();
> +	writel(AICA_CMD_KICK | AICA_CMD_START,
> +	       (uint32_t *) AICA_CONTROL_POINT);
> +
> +}
> +
> +inline static void aica_chn_halt()
> +{
> +	spu_write_wait();
> +	writel(AICA_CMD_KICK | AICA_CMD_STOP,
> +	       (uint32_t *) AICA_CONTROL_POINT);
> +
> +}
> +
> +
> +/* ALSA code below */
> +
> +static snd_pcm_hardware_t snd_pcm_aica_playback_hw = {

Use struct snd_pcm_hardware, instead.
Refer either ALSA-1.0.11rc4 or 2.6.16 tree.


> +
> +	.info = (SNDRV_PCM_INFO_NONINTERLEAVED),
> +	.formats =
> +	    (SNDRV_PCM_FMTBIT_S8 | SNDRV_PCM_FMTBIT_S16_LE |
> +	     SNDRV_PCM_FMTBIT_IMA_ADPCM),
> +	.rates = SNDRV_PCM_RATE_8000_48000,
> +	.rate_min = 8000,
> +	.rate_max = 48000,
> +	.channels_min = 1,
> +	.channels_max = 2,
> +	.buffer_bytes_max = AICA_BUFFER_SIZE,
> +	.period_bytes_min = AICA_PERIOD_SIZE,
> +	.period_bytes_max = AICA_PERIOD_SIZE,
> +	.periods_min = AICA_PERIOD_NUMBER,
> +	.periods_max = AICA_PERIOD_NUMBER,
> +};
> +
> +/* There is only one sound card on a Dreamcast */
> +static snd_card_aica_t *dreamcastcard = NULL;

Is this static variable really needed?


> +static struct platform_device *pd = NULL;
> +
> +
> +
> +
> +static int stereo_buffer_transfer(snd_pcm_substream_t * substream,

Use struct snd_pcm_substream.

> +				  int buffer_size, int period)
> +{
> +	int transferred;
> +	snd_pcm_runtime_t *runtime;

Use struct snd_pcm_runtime....  in many other places, too.

> +	int period_offset;
> +	period_offset = period;
> +	period_offset %= (AICA_PERIOD_NUMBER / 2);
> +	runtime = substream->runtime;
> +
> +	//snd_printk("period is 0x%X, period_offset is 0x%X, buffer_size is 0x%X\n", period, period_offset, buffer_size);
> +	/* transfer left and then right */
> +	dma_xfer(0,
> +		 runtime->dma_area + (AICA_PERIOD_SIZE * period_offset),
> +		 AICA_CHANNEL0_OFFSET + (AICA_PERIOD_SIZE * period_offset),
> +		 buffer_size / 2, 5);
> +	/* wait for completion */
> +	do {
> +		udelay(5);
> +		transferred = get_dma_residue(0);
> +	}
> +	while (transferred < buffer_size / 2);

Hmm, is this a correct implementation?  It doesf looping in a timer
handler.  Surely it works, but...


> +	dma_xfer(0,
> +		 AICA_BUFFER_SIZE / 2 + runtime->dma_area +
> +		 (AICA_PERIOD_SIZE * period_offset),
> +		 AICA_CHANNEL1_OFFSET + (AICA_PERIOD_SIZE * period_offset),
> +		 buffer_size / 2, 5);
> +	/* have to wait again */
> +	do {
> +		udelay(5);
> +		transferred = get_dma_residue(0);
> +	}
> +	while (transferred < buffer_size / 2);

Ditto.

> +	return 0;
> +}
> +
> +
> +
> +
> +void aica_period_elapsed(unsigned long timer_var)
> +{
> +	int transferred;
> +	int play_period;
> +	snd_pcm_runtime_t *runtime;
> +	runtime = (dreamcastcard->substream)->runtime;

You can use the argument (timer_var) to retrieve an object.

> +
> +	/* Have we played out an additional period? */
> +	play_period =
> +	    frames_to_bytes(runtime,
> +			    readl
> +			    (AICA_CONTROL_CHANNEL_SAMPLE_NUMBER)) /
> +	    AICA_PERIOD_SIZE;
> +	if (play_period == dreamcastcard->current_period) {
> +		dreamcastcard->timer.expires = jiffies + 1;
> +		add_timer(&(dreamcastcard->timer));

I guess you need a proper lock to avoid race here?

> +		return;
> +	}
> +	if (runtime->channels > 1) {
> +		dreamcastcard->current_period = play_period;	/*TO DO: Work out why this doesn't work for 1 channel */
> +
> +		stereo_buffer_transfer(dreamcastcard->substream,
> +				       AICA_PERIOD_SIZE * 2,
> +				       dreamcastcard->clicks);
> +	} else {
> +		dma_xfer(0,
> +			 runtime->dma_area +
> +			 (AICA_PERIOD_SIZE * dreamcastcard->clicks),
> +			 AICA_CHANNEL0_OFFSET +
> +			 (AICA_PERIOD_SIZE * dreamcastcard->clicks),
> +			 AICA_PERIOD_SIZE, 5);
> +		do {
> +			/* Try to fine tune the delay to keep it as short as possible */
> +			udelay(5);
> +			/* get_dma_residue reports residue until completion when it reports total bytes transferred */
> +			transferred = get_dma_residue(0);
> +		}
> +		while (transferred < AICA_PERIOD_SIZE);

Another busy loop in timer callback.

> +	}
> +
> +	snd_pcm_period_elapsed(dreamcastcard->substream);
> +	dreamcastcard->clicks++;
> +	dreamcastcard->clicks %= AICA_PERIOD_NUMBER;
> +	/* reschedule the timer */
> +	dreamcastcard->timer.expires = jiffies + 1;
> +	add_timer(&(dreamcastcard->timer));
> +	return;
> +}
> +
> +static int snd_aicapcm_pcm_open(snd_pcm_substream_t * substream)
> +{
> +	if (!enable) return -ENOENT;

This check is useless.  If needed, do it in module initialization.

> +	channel = kmalloc(sizeof(aica_channel_t), GFP_KERNEL);
> +	if (!channel)
> +		return -ENOMEM;
> +	/* set defaults for channel */
> +	channel->sfmt = SM_8BIT;
> +	channel->cmd = AICA_CMD_START;
> +	channel->vol = dreamcastcard->master_volume;
> +	channel->pan = 0x80;
> +	channel->pos = 0;
> +	channel->flags = 0;	/* default to mono */
> +	snd_pcm_runtime_t *runtime;

Should be in the beginning of the function.

> +	runtime = substream->runtime;
> +	runtime->hw = snd_pcm_aica_playback_hw;
> +	spu_enable();
> +	dreamcastcard->clicks = 0;
> +	dreamcastcard->current_period = 0;
> +	return 0;
> +
> +}
> +
> +static int snd_aicapcm_pcm_close(snd_pcm_substream_t * substream)
> +{
> +	del_timer(&dreamcastcard->timer);
> +	kfree(channel);
> +	spu_disable();
> +	return 0;
> +}
> +
> +static int snd_aicapcm_pcm_hw_free(snd_pcm_substream_t * substream)
> +{
> +	/* Free the DMA buffer */
> +	return snd_pcm_lib_free_pages(substream);
> +}
> +
> +static int snd_aicapcm_pcm_hw_params(snd_pcm_substream_t * substream,
> +				     snd_pcm_hw_params_t * hw_params)
> +{
> +	/* Allocate a DMA buffer using ALSA built-ins */
> +	return
> +	    snd_pcm_lib_malloc_pages(substream,
> +				     params_buffer_bytes(hw_params));
> +}
> +
> +static int snd_aicapcm_pcm_prepare(snd_pcm_substream_t * substream)
> +{
> +
> +	/* Set up the playback */
> +	/* basic settings to test working */
> +	if ((substream->runtime)->format == SNDRV_PCM_FORMAT_S16_LE)
> +		channel->sfmt = SM_16BIT;
> +	channel->freq = substream->runtime->rate;
> +	dreamcastcard->substream = substream;

This one is never unset...

> +	return 0;
> +}
> +
> +
> +static void startup_aica()
> +{
> +	spu_memload(AICA_CHANNEL0_CONTROL_OFFSET, (uint8_t *) channel,
> +		    sizeof(aica_channel_t));
> +	aica_chn_start();
> +	return;
> +}
> +
> +
> +static void spu_begin_dma(snd_pcm_substream_t * substream)
> +{
> +	int buffer_size;
> +	snd_pcm_runtime_t *runtime;
> +	runtime = substream->runtime;
> +	buffer_size = frames_to_bytes(runtime, runtime->buffer_size);
> +	if (runtime->channels == 1)
> +		dma_xfer(0, runtime->dma_area, AICA_CHANNEL0_OFFSET,
> +			 buffer_size, 5);
> +	else {
> +		int transfer_status;
> +		channel->flags |= 0x01;
> +		transfer_status =
> +		    stereo_buffer_transfer(substream, buffer_size, 0);
> +		if (transfer_status != 0)
> +			return;
> +		dreamcastcard->clicks =
> +		    buffer_size / (AICA_PERIOD_SIZE * runtime->channels);
> +	}
> +	startup_aica();
> +	init_timer(&(dreamcastcard->timer));
> +	dreamcastcard->timer.function = aica_period_elapsed;

This is dangerous.  The timer can be running, e.g. when a PCM stream
is replayed.

> +
> +
> +	dreamcastcard->timer.expires = jiffies + 4;

Why 4?

> +	add_timer(&(dreamcastcard->timer));
> +	return;
> +}
> +
> +static int snd_aicapcm_pcm_trigger(snd_pcm_substream_t * substream,
> +				   int cmd)
> +{
> +
> +	switch (cmd) {
> +	case SNDRV_PCM_TRIGGER_START:
> +		spu_begin_dma(substream);
> +		break;
> +	case SNDRV_PCM_TRIGGER_STOP:
> +		aica_chn_halt();

Isn't better to stop the timer here?

> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +
> +	return 0;
> +}
> +
> +static snd_pcm_uframes_t snd_aicapcm_pcm_pointer(snd_pcm_substream_t *
> +						 substream)
> +{
> +	return readl(AICA_CONTROL_CHANNEL_SAMPLE_NUMBER);
> +
> +}
> +
> +
> +static snd_pcm_ops_t snd_aicapcm_playback_ops = {
> +	.open = snd_aicapcm_pcm_open,
> +	.close = snd_aicapcm_pcm_close,
> +	.ioctl = snd_pcm_lib_ioctl,
> +	.hw_params = snd_aicapcm_pcm_hw_params,
> +	.hw_free = snd_aicapcm_pcm_hw_free,
> +	.prepare = snd_aicapcm_pcm_prepare,
> +	.trigger = snd_aicapcm_pcm_trigger,
> +	.pointer = snd_aicapcm_pcm_pointer,
> +};
> +
> +
> +static int snd_aicapcm_free(snd_card_aica_t * dreamcastcard)
> +{
> +	release_mem_region(ARM_RESET_REGISTER, 0x4);
> +	release_mem_region(SPU_MEMORY_BASE, 0x200000);
> +	return 0;
> +}
> +
> +/*	Set up the PCM playback device
> +	card is pointer to the overall AICA device
> +	pcm_index is number of PCM instances - 1
> +
> +	TO DO: set up to handle more than one pcm instance
> +*/
> +
> +
> +static int __init snd_aicapcmchip(snd_card_aica_t * dreamcastcard,
> +				  int pcm_index)
> +{
> +	snd_pcm_t *pcm;
> +	int err;
> +
> +	/* Can we lock the memory */
> +
> +	if (request_mem_region(ARM_RESET_REGISTER, 4, "AICA ARM control")
> +	    == NULL)
> +		return -ENOMEM;
> +	if (request_mem_region(SPU_MEMORY_BASE, 0x200000, "AICA Sound RAM")
> +	    == NULL) {
> +		release_mem_region(ARM_RESET_REGISTER, 0x4);
> +		return -ENOMEM;
> +	}
> +
> +	/* AICA has no capture ability */
> +	if ((err =
> +	     snd_pcm_new(dreamcastcard->card, "AICA PCM", pcm_index, 1, 0,
> +			 &pcm)) < 0)
> +		return err;
> +	pcm->private_data = dreamcastcard;
> +	dreamcastcard->card->private_data = pcm;

What the purpose of this assignment?

> +	strcpy(pcm->name, "AICA PCM");
> +
> +	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK,
> +			&snd_aicapcm_playback_ops);
> +
> +	/* Allocate the DMA buffers */
> +	err =
> +	    snd_pcm_lib_preallocate_pages_for_all(pcm,
> +						  SNDRV_DMA_TYPE_CONTINUOUS,
> +						  snd_dma_continuous_data
> +						  (GFP_KERNEL),
> +						  AICA_BUFFER_SIZE,
> +						  AICA_BUFFER_SIZE);
> +
> +	return err;
> +}
> +
> +/* Mixer controls */
> +static int aica_pcmswitch_info(snd_kcontrol_t * kcontrol,
> +			       snd_ctl_elem_info_t * uinfo)
> +{
> +	uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
> +	uinfo->count = 1;
> +	uinfo->value.integer.min = 0;
> +	uinfo->value.integer.max = 1;
> +	return 0;
> +}
> +
> +static int aica_pcmswitch_get(snd_kcontrol_t * kcontrol,
> +			      snd_ctl_elem_value_t * ucontrol)
> +{
> +	ucontrol->value.integer.value[0] = 1;	/* TO DO: Fix me */
> +	return 0;
> +}
> +
> +static int aica_pcmswitch_put(snd_kcontrol_t * kcontrol,
> +			      snd_ctl_elem_value_t * ucontrol)
> +{
> +	if (ucontrol->value.integer.value[0] == 1)
> +		return 0;	/* TO DO: Fix me */
> +	else
> +		aica_chn_halt();
> +	return 0;
> +}

I guess this doesn't work (to reenable the DMA)?


> +static int aica_pcmvolume_info(snd_kcontrol_t * kcontrol,
> +			       snd_ctl_elem_info_t * uinfo)
> +{
> +
> +	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
> +	uinfo->count = 1;
> +	uinfo->value.integer.min = 0;
> +	uinfo->value.integer.max = 0xFF;
> +
> +	return 0;
> +}
> +
> +static int aica_pcmvolume_get(snd_kcontrol_t * kcontrol,
> +			      snd_ctl_elem_value_t * ucontrol)
> +{
> +	if (!channel)
> +		return -ETXTBSY;	/* we've not yet been set up */
> +	ucontrol->value.integer.value[0] = channel->vol;
> +	return 0;
> +}
> +
> +static int aica_pcmvolume_put(snd_kcontrol_t * kcontrol,
> +			      snd_ctl_elem_value_t * ucontrol)
> +{
> +	if (!channel) {
> +		snd_printk("No channel yet\n");
> +		return -ETXTBSY;	/* too soon */
> +	}
> +
> +	else if (channel->vol == ucontrol->value.integer.value[0])
> +		return 0;
> +
> +	else {
> +		channel->vol = ucontrol->value.integer.value[0];
> +		dreamcastcard->master_volume = ucontrol->value.integer.value[0];
> +		spu_memload(AICA_CHANNEL0_CONTROL_OFFSET,
> +			    (uint8_t *) channel, sizeof(aica_channel_t));
> +	}
> +	return 1;
> +}
> +
> +static snd_kcontrol_new_t snd_aica_masterswitch_control __devinitdata = {
> +	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
> +	.name = "Playback Switch",

Should be "Master Playback Switch".

> +	.info = aica_pcmswitch_info,
> +	.get = aica_pcmswitch_get,
> +	.put = aica_pcmswitch_put
> +};

... But why do you need two different switches for the very same
thing? 

> +static snd_kcontrol_new_t snd_aica_pcmswitch_control __devinitdata = {
> +	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
> +	.name = "PCM Playback Switch",
> +	.index = 0,
> +	.info = aica_pcmswitch_info,
> +	.get = aica_pcmswitch_get,
> +	.put = aica_pcmswitch_put
> +};
> +
> +
> +static snd_kcontrol_new_t snd_aica_mastervolume_control __devinitdata = {
> +	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
> +	.name = "Playback Volume",

Should be "Master Playback Volume".

> +	.info = aica_pcmvolume_info,
> +	.get = aica_pcmvolume_get,
> +	.put = aica_pcmvolume_put
> +};
> +
> +static snd_kcontrol_new_t snd_aica_pcmvolume_control __devinitdata = {
> +	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
> +	.name = "PCM Playback Volume",
> +	.index = 0,
> +	.info = aica_pcmvolume_info,
> +	.get = aica_pcmvolume_get,
> +	.put = aica_pcmvolume_put
> +};

... And again two mixer elements for the very same volume control.


> +
> +
> +static struct device_driver aica_driver = {
> +	.name = "AICA",
> +	.bus = &platform_bus_type,
> +};
> +
> +
> +/* Fill up the members of the embedded device structure */
> +
> +static void populate_dreamcastaicadev(struct device *dev)
> +{
> +	dev->bus = &platform_bus_type;
> +	dev->driver = &aica_driver;
> +	driver_register(dev->driver);
> +	device_bind_driver(dev);
> +}

Looks not right for the recent platform_device...
You can do it better in platform_driver.probe and remove callbacks.


> +static int load_aica_firmware()
> +{
> +	int err;
> +	err = 0;
> +	spu_init();
> +	const struct firmware *fw_entry;
> +	err = request_firmware(&fw_entry, "aica_firmware.bin", &pd->dev);
> +	if (err)
> +		return err;
> +	/* write firware into memory */
> +	spu_disable();
> +	spu_memload(0, fw_entry->data, fw_entry->size);
> +	spu_enable();
> +	release_firmware(fw_entry);
> +	return err;
> +}
> +
> +static int __devinit add_aicamixer_controls()
> +{
> +	int err;
> +	err = snd_ctl_add
> +	     (dreamcastcard->card,
> +	      snd_ctl_new1(&snd_aica_pcmvolume_control,
> +			   dreamcastcard));
> +	     if (err < 0){
> +		snd_printk("pcmvolume failed\n");
> +		return err;
> +	     }
> +	    
> +	    err= snd_ctl_add
> +	     (dreamcastcard->card,
> +	      snd_ctl_new1(&snd_aica_pcmswitch_control,
> +			   dreamcastcard));
> +	     if (err < 0){
> +		snd_printk("pcmswitch failed\n");
> +		return err;
> +	     }
> +
> +	    
> +	    err = snd_ctl_add
> +	     (dreamcastcard->card,
> +	      snd_ctl_new1(&snd_aica_mastervolume_control,
> +			   dreamcastcard));
> +	     if (err < 0){
> +		snd_printk("mastervolume failed\n");
> +		return err;
> +	     }
> +
> +	    
> +	    err = snd_ctl_add
> +	     (dreamcastcard->card,
> +	      snd_ctl_new1(&snd_aica_masterswitch_control,
> +			   dreamcastcard));
> +	     if (err < 0){
> +		snd_printk("masterswitch failed\n");
> +		return err;
> +	     }
> +
> +	    
> +	  
> +	/* succeeded */
> +	return 0;
> +}
> +
> +
> +
> +static int __init aica_init(void)
> +{
> +
> +
> +	int err;
> +	int idx;
> +
> +	/* Are we in a Dreamcast at all? */
> +	if (!mach_is_dreamcast())
> +		return -ENODEV;
> +	dreamcastcard = kmalloc(sizeof(snd_card_aica_t), GFP_KERNEL);
> +	if (!dreamcastcard)
> +		return -ENOMEM;
> +	dreamcastcard->card = NULL;
> +	/* Can only be one real device on a Dreamcast
> +	   but we might have the dummy or some other driver loaded */
> +	for (idx = 0; idx < SNDRV_CARDS; idx++) {
> +		dreamcastcard->card =
> +		    snd_card_new(idx, "AICA", THIS_MODULE, 0);
> +		if (dreamcastcard->card)
> +			break;
> +	}

The code looks odd.  Simply call snd_card_new() once because this driver
supports only one instance anyway.

> +	if (!dreamcastcard->card) {
> +		kfree(dreamcastcard);
> +		return -ENODEV;
> +	}
> +	strcpy(dreamcastcard->card->driver, "snd_card_aica");
> +	strcpy(dreamcastcard->card->shortname, "AICA");
> +	strcpy(dreamcastcard->card->longname,
> +	       "Yamaha AICA Super Intelligent Sound Processor for SEGA Dreamcast");
> +
> +	/* Load the PCM 'chip' */
> +	if ((err = snd_aicapcmchip(dreamcastcard, 0)) < 0)
> +		goto freedreamcast;
> +
> +
> +	pd = platform_device_register_simple(dreamcastcard->card->driver,
> +					     -1, NULL, 0);
> +
> +	if (IS_ERR(pd)) {
> +		err = -ENODEV;
> +		goto freepcm;
> +	}
> +
> +	populate_dreamcastaicadev(&pd->dev);
> +	snd_card_set_dev(dreamcastcard->card, &pd->dev);
> +	/* Register the card with ALSA subsystem */
> +	if ((err = snd_card_register(dreamcastcard->card)) < 0)
> +		goto freepcm;
> +
> +	/* Load the firmware */
> +	err = load_aica_firmware();

The firmware should be loaded before registration of the card
instance.  snd_card_register() will create device files.  It means
that user-space apps are allowed to access the driver.

> +
> +	if (err)
> +		goto freepcm;
> +
> +
> +	/* Add basic controls */
> +	if (add_aicamixer_controls() < 0) goto freepcm;

This should be done before snd_card_register(), too.


> +	snd_printk
> +	    ("ALSA Driver for Yamaha AICA Super Intelligent Sound Processor on slot %d\n",
> +	     idx);
> +
> +	return 0;
> +
> +      freepcm:
> +	snd_aicapcm_free(dreamcastcard);
> +
> +      freedreamcast:
> +	snd_card_free(dreamcastcard->card);
> +
> +	if (pd) {
> +		struct device_driver *drv = (&pd->dev)->driver;
> +		device_release_driver(&pd->dev);
> +		driver_unregister(drv);
> +		platform_device_unregister(pd);
> +		pd = NULL;
> +	}
> +	kfree(dreamcastcard);
> +	return err;
> +
> +
> +}
> +
> +static void __exit aica_exit(void)
> +{
> +
> +	if (likely(dreamcastcard->card)) {

You don't need such an optimization in this place at all.

> +		snd_aicapcm_free(dreamcastcard);
> +		snd_card_free(dreamcastcard->card);
> +		kfree(dreamcastcard);
> +		if (likely(pd)) {
> +			struct device_driver *drv = (&pd->dev)->driver;
> +			device_release_driver(&pd->dev);
> +			driver_unregister(drv);
> +			platform_device_unregister(pd);
> +		}

This should be in remove callback.


Takashi
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