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drm: apple: audio: legacy path: 256 KiB audio elements, PM reference held until the DMA stopped #1697

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drm: apple: audio: legacy path: 256 KiB audio elements, PM reference held until the DMA stopped #1697

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217ad61
drm: apple: audio: ask for up to 256 KiB of audio elements, as macOS
Oct 11, 2026
36d7929
drm: apple: audio: drop the runtime PM reference only after the DMA s…
Oct 11, 2026
d060023
drm: apple: audio: test the legacy stream's PM reference and element …
RyanTheTide Nov 12, 2026
27f1c0d
selftests: apple-dcp, apple-afkv2: kvzalloc() and kvfree() for the ca…
RyanTheTide Nov 12, 2026
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8 changes: 4 additions & 4 deletions drivers/gpu/drm/apple/afk.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3186,7 +3186,7 @@ int afk_service_call_timeout_len(struct apple_epic_service *service, u16 group,
if (!service)
return -ENODEV;

bfr = kzalloc(bfr_len, GFP_KERNEL);
bfr = kvzalloc(bfr_len, GFP_KERNEL);
if (!bfr)
return -ENOMEM;

Expand Down Expand Up @@ -3256,7 +3256,7 @@ int afk_service_call_timeout_len(struct apple_epic_service *service, u16 group,
}

out:
kfree(bfr);
kvfree(bfr);
return ret;
}

Expand Down Expand Up @@ -3294,7 +3294,7 @@ int afk_service_call_with_reply_len(struct apple_epic_service *service,
&bfr_len) || bfr_len > U32_MAX)
return -EOVERFLOW;

bfr = kzalloc(bfr_len, GFP_KERNEL);
bfr = kvzalloc(bfr_len, GFP_KERNEL);
if (!bfr)
return -ENOMEM;

Expand Down Expand Up @@ -3339,7 +3339,7 @@ int afk_service_call_with_reply_len(struct apple_epic_service *service,
}

out:
kfree(bfr);
kvfree(bfr);
return ret;
}

Expand Down
302 changes: 302 additions & 0 deletions drivers/gpu/drm/apple/audio-legacy-test.c
View file
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Original file line number Diff line number Diff line change
@@ -0,0 +1,302 @@
// SPDX-License-Identifier: GPL-2.0-only OR MIT
/*
* Included by audio.c: on the legacy (pre-14.7) audio service a stopped
* stream keeps its runtime PM reference until sync_stop has waited for the
* DMA terminate, a failed START leaves exactly one reference to put, and the
* element catalog is asked for with the full 256 KiB capacity.
* The production trigger and sync_stop run; the audio service's link calls
* and the DMA channel are stubbed.
*/
#include <kunit/platform_device.h>
#include <kunit/static_stub.h>
#include <kunit/test.h>

struct dcpaud_legacy_test {
struct dma_device dma;
struct dma_chan channel;
struct dma_async_tx_descriptor desc;
char sequence[32];
unsigned int nsequence;
/* The runtime PM usage count when the terminate was waited for */
int usage_at_drain;
int startlink_err;
size_t elements_asked;
size_t catalog;
struct device *dev;
};

static struct dcpaud_legacy_test *dcpaud_legacy_current;

static void dcpaud_legacy_record(char step)
{
struct dcpaud_legacy_test *t = dcpaud_legacy_current;

if (t->nsequence < sizeof(t->sequence) - 1)
t->sequence[t->nsequence++] = step;
}

static int dcpaud_legacy_terminate(struct dma_chan *chan)
{
dcpaud_legacy_record('X');
return 0;
}

static void dcpaud_legacy_drain(struct dma_chan *chan)
{
struct dcpaud_legacy_test *t = dcpaud_legacy_current;

t->usage_at_drain = atomic_read(&t->dev->power.usage_count);
dcpaud_legacy_record('D');
}

static dma_cookie_t dcpaud_legacy_submit(struct dma_async_tx_descriptor *tx)
{
return 1;
}

static struct dma_async_tx_descriptor *
dcpaud_legacy_prep(struct dma_chan *chan, dma_addr_t buf, size_t len, size_t period,
enum dma_transfer_direction dir, unsigned long flags)
{
struct dcpaud_legacy_test *t = dcpaud_legacy_current;

dcpaud_legacy_record('Q');
t->desc.chan = chan;
t->desc.tx_submit = dcpaud_legacy_submit;
return &t->desc;
}

static void dcpaud_legacy_issue(struct dma_chan *chan)
{
}

static enum dma_status dcpaud_legacy_status(struct dma_chan *chan, dma_cookie_t cookie,
struct dma_tx_state *state)
{
return DMA_COMPLETE;
}

static int dcpaud_legacy_startlink(struct device *dev, struct dcp_sound_cookie *cookie)
{
dcpaud_legacy_record('T');
return dcpaud_legacy_current->startlink_err;
}

static int dcpaud_legacy_stoplink(struct device *dev)
{
dcpaud_legacy_record('S');
return 0;
}

static void dcpaud_legacy_rpm_disable(void *data)
{
pm_runtime_disable(data);
}

static void dcpaud_legacy_close(void *data)
{
snd_dmaengine_pcm_close(data);
}

/* A legacy service instance with a sink, and a configured stream on it */
static struct snd_pcm_substream *dcpaud_legacy_setup(struct kunit *test,
struct dcp_audio **audio)
{
struct dcpaud_legacy_test *t = kunit_kzalloc(test, sizeof(*t), GFP_KERNEL);
struct dcp_audio *dcpaud = kunit_kzalloc(test, sizeof(*dcpaud), GFP_KERNEL);
struct snd_pcm_substream *sub = kunit_kzalloc(test, sizeof(*sub), GFP_KERNEL);
struct snd_pcm_runtime *runtime = kunit_kzalloc(test, sizeof(*runtime), GFP_KERNEL);
struct snd_pcm *pcm = kunit_kzalloc(test, sizeof(*pcm), GFP_KERNEL);
struct platform_device *pdev;

KUNIT_ASSERT_NOT_NULL(test, t);
KUNIT_ASSERT_NOT_NULL(test, dcpaud);
KUNIT_ASSERT_NOT_NULL(test, sub);
KUNIT_ASSERT_NOT_NULL(test, runtime);
KUNIT_ASSERT_NOT_NULL(test, pcm);
pdev = kunit_platform_device_alloc(test, "dcpaud-legacy", PLATFORM_DEVID_AUTO);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, pdev);
platform_set_drvdata(pdev, dcpaud);
dcpaud->dev = &pdev->dev;
dcpaud->dcp_dev = &pdev->dev;
mutex_init(&dcpaud->data_lock);
INIT_DELAYED_WORK(&dcpaud->void_work, dcpaud_void_work);
dcpaud->connected = true;
dcpaud->substream = sub;

/* Runtime PM on, without callbacks: only the usage count matters */
pm_runtime_no_callbacks(dcpaud->dev);
pm_runtime_enable(dcpaud->dev);
KUNIT_ASSERT_EQ(test, kunit_add_action_or_reset(test, dcpaud_legacy_rpm_disable,
dcpaud->dev), 0);

dcpaud_legacy_current = t;
t->dev = dcpaud->dev;
t->usage_at_drain = -1;
t->channel.device = &t->dma;
t->dma.device_terminate_all = dcpaud_legacy_terminate;
t->dma.device_synchronize = dcpaud_legacy_drain;
t->dma.device_tx_status = dcpaud_legacy_status;
t->dma.device_prep_dma_cyclic = dcpaud_legacy_prep;
t->dma.device_issue_pending = dcpaud_legacy_issue;
kunit_activate_static_stub(test, dcp_audiosrv_startlink, dcpaud_legacy_startlink);
kunit_activate_static_stub(test, dcp_audiosrv_stoplink, dcpaud_legacy_stoplink);

pcm->private_data = dcpaud;
pcm->nonatomic = true;
sub->pcm = pcm;
sub->runtime = runtime;
mutex_init(&sub->self_group.mutex);
spin_lock_init(&sub->self_group.lock);
sub->group = &sub->self_group;
runtime->frame_bits = 64;
runtime->rate = 48000;
runtime->buffer_size = 8192;
runtime->period_size = 512;
KUNIT_ASSERT_EQ(test, snd_dmaengine_pcm_open(sub, &t->channel), 0);
KUNIT_ASSERT_EQ(test, kunit_add_action_or_reset(test, dcpaud_legacy_close, sub), 0);

*audio = dcpaud;
return sub;
}

static int dcpaud_legacy_usage(struct dcp_audio *dcpaud)
{
return atomic_read(&dcpaud->dev->power.usage_count);
}

static void dcpaud_legacy_stop_waits_for_dma(struct kunit *test)
{
struct dcp_audio *audio;
struct snd_pcm_substream *sub = dcpaud_legacy_setup(test, &audio);

KUNIT_ASSERT_EQ(test, dcp_pcm_trigger(sub, SNDRV_PCM_TRIGGER_START), 0);
KUNIT_EXPECT_EQ(test, dcpaud_legacy_usage(audio), 1);

/* The terminate is only started: the DPA stays powered */
KUNIT_ASSERT_EQ(test, dcp_pcm_trigger(sub, SNDRV_PCM_TRIGGER_STOP), 0);
KUNIT_EXPECT_STREQ(test, dcpaud_legacy_current->sequence, "TQXS");
KUNIT_EXPECT_EQ(test, dcpaud_legacy_usage(audio), 1);

/* The reference goes once the terminate was waited for */
KUNIT_ASSERT_EQ(test, dcp_pcm_sync_stop(sub), 0);
KUNIT_EXPECT_STREQ(test, dcpaud_legacy_current->sequence, "TQXSD");
KUNIT_EXPECT_EQ(test, dcpaud_legacy_current->usage_at_drain, 1);
KUNIT_EXPECT_EQ(test, dcpaud_legacy_usage(audio), 0);
KUNIT_EXPECT_FALSE(test, audio->pm_held);

/* A second sync_stop (close after prepare) has nothing to put */
KUNIT_ASSERT_EQ(test, dcp_pcm_sync_stop(sub), 0);
KUNIT_EXPECT_EQ(test, dcpaud_legacy_usage(audio), 0);
}

static void dcpaud_legacy_suspend_waits_for_dma(struct kunit *test)
{
struct dcp_audio *audio;
struct snd_pcm_substream *sub = dcpaud_legacy_setup(test, &audio);

KUNIT_ASSERT_EQ(test, dcp_pcm_trigger(sub, SNDRV_PCM_TRIGGER_START), 0);
KUNIT_ASSERT_EQ(test, dcp_pcm_trigger(sub, SNDRV_PCM_TRIGGER_SUSPEND), 0);
KUNIT_EXPECT_EQ(test, dcpaud_legacy_usage(audio), 1);
KUNIT_ASSERT_EQ(test, dcp_pcm_sync_stop(sub), 0);
KUNIT_EXPECT_STREQ(test, dcpaud_legacy_current->sequence, "TQXSD");
KUNIT_EXPECT_EQ(test, dcpaud_legacy_current->usage_at_drain, 1);
KUNIT_EXPECT_EQ(test, dcpaud_legacy_usage(audio), 0);
}

static void dcpaud_legacy_failed_start(struct kunit *test)
{
struct dcp_audio *audio;
struct snd_pcm_substream *sub = dcpaud_legacy_setup(test, &audio);

/* START fails at the link; ALSA undoes it with a STOP */
dcpaud_legacy_current->startlink_err = -EIO;
KUNIT_ASSERT_EQ(test, dcp_pcm_trigger(sub, SNDRV_PCM_TRIGGER_START), -EIO);
KUNIT_ASSERT_EQ(test, dcp_pcm_trigger(sub, SNDRV_PCM_TRIGGER_STOP), 0);
KUNIT_EXPECT_EQ(test, dcpaud_legacy_usage(audio), 1);

/* Retried before sync_stop ran: still one reference */
dcpaud_legacy_current->startlink_err = 0;
KUNIT_ASSERT_EQ(test, dcp_pcm_trigger(sub, SNDRV_PCM_TRIGGER_START), 0);
KUNIT_EXPECT_EQ(test, dcpaud_legacy_usage(audio), 1);
KUNIT_ASSERT_EQ(test, dcp_pcm_trigger(sub, SNDRV_PCM_TRIGGER_STOP), 0);
KUNIT_ASSERT_EQ(test, dcp_pcm_sync_stop(sub), 0);
KUNIT_EXPECT_STREQ(test, dcpaud_legacy_current->sequence, "TXSTQXSD");
KUNIT_EXPECT_EQ(test, dcpaud_legacy_usage(audio), 0);
}

static void dcpaud_legacy_void_takes_no_reference(struct kunit *test)
{
struct dcp_audio *audio;
struct snd_pcm_substream *sub = dcpaud_legacy_setup(test, &audio);

/* No sink: the stream plays into the void; a 10 s period never elapses here */
audio->open_unplugged = true;
sub->runtime->period_size = 480000;
KUNIT_ASSERT_EQ(test, dcp_pcm_trigger(sub, SNDRV_PCM_TRIGGER_START), 0);
KUNIT_EXPECT_TRUE(test, audio->void_running);
KUNIT_ASSERT_EQ(test, dcp_pcm_trigger(sub, SNDRV_PCM_TRIGGER_STOP), 0);
KUNIT_ASSERT_EQ(test, dcp_pcm_sync_stop(sub), 0);
KUNIT_EXPECT_STREQ(test, dcpaud_legacy_current->sequence, "D");
KUNIT_EXPECT_EQ(test, dcpaud_legacy_usage(audio), 0);
}

static int dcpaud_legacy_get_elements(struct device *dev, void *elements, size_t maxsize)
{
struct dcpaud_legacy_test *t = dcpaud_legacy_current;

t->elements_asked = maxsize;
/* What the service returns: cut off at the buffer's end */
memset(elements, 0xa5, min(t->catalog, maxsize));
return 0;
}

static int dcpaud_legacy_get_attrs(struct device *dev, void *attrs, size_t maxsize)
{
return 0;
}

static void dcpaud_legacy_free(void *data)
{
kvfree(data);
}

static void dcpaud_legacy_elements_capacity(struct kunit *test)
{
struct dcp_audio *audio;
u8 *elements;

dcpaud_legacy_setup(test, &audio);
elements = kvzalloc(DCPAUD_ELEMENTS_MAXSIZE, GFP_KERNEL);
KUNIT_ASSERT_NOT_NULL(test, elements);
KUNIT_ASSERT_EQ(test, kunit_add_action_or_reset(test, dcpaud_legacy_free, elements), 0);
audio->elements = elements;
audio->productattrs = kunit_kzalloc(test, DCPAUD_PRODUCTATTRS_MAXSIZE, GFP_KERNEL);
KUNIT_ASSERT_NOT_NULL(test, audio->productattrs);
kunit_activate_static_stub(test, dcp_audiosrv_get_elements, dcpaud_legacy_get_elements);
kunit_activate_static_stub(test, dcp_audiosrv_get_product_attrs, dcpaud_legacy_get_attrs);

/* A TV behind a USB-C to HDMI adapter: 17312 bytes of elements */
dcpaud_legacy_current->catalog = 17312;
KUNIT_ASSERT_FALSE(test, dcpaud_native_link(audio));
KUNIT_ASSERT_EQ(test, dcpaud_read_remote_info(audio), 0);
KUNIT_EXPECT_EQ(test, dcpaud_legacy_current->elements_asked, (size_t)SZ_256K);
KUNIT_EXPECT_EQ(test, elements[17311], 0xa5);
KUNIT_EXPECT_EQ(test, elements[17312], 0);
}

static struct kunit_case dcpaud_legacy_cases[] = {
KUNIT_CASE(dcpaud_legacy_stop_waits_for_dma),
KUNIT_CASE(dcpaud_legacy_suspend_waits_for_dma),
KUNIT_CASE(dcpaud_legacy_failed_start),
KUNIT_CASE(dcpaud_legacy_void_takes_no_reference),
KUNIT_CASE(dcpaud_legacy_elements_capacity),
{}
};

static struct kunit_suite dcpaud_legacy_suite = {
.name = "apple-dcpaud-legacy",
.test_cases = dcpaud_legacy_cases,
};

kunit_test_suite(dcpaud_legacy_suite);
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