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drm: apple: audio: limit the number of periods to what SIO can serve #277

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drm: apple: audio: limit the number of periods to what SIO can serve #277

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13 changes: 10 additions & 3 deletions drivers/gpu/drm/apple/audio.c
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Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,13 @@
#define DCPAUD_ELEMENTS_MAXSIZE 16384
#define DCPAUD_PRODUCTATTRS_MAXSIZE 1024

/*
* SIO takes one of its 64 descriptor slots per period, shared by all its
* channels, and up to three DP audio outputs use one SIO. A stream with
* more periods fails START with -ENOMEM.
*/
#define DCPAUD_PERIODS_MAX 16

struct dcp_audio {
struct device *dev;
struct device *dcp_dev;
Expand Down Expand Up @@ -72,7 +79,7 @@ static const struct snd_pcm_hardware dcp_pcm_hw = {
.period_bytes_min = 4096, /* TODO */
.period_bytes_max = SIZE_MAX,
.periods_min = 2,
.periods_max = UINT_MAX,
.periods_max = DCPAUD_PERIODS_MAX,
};

/*
Expand All @@ -98,7 +105,7 @@ static const struct snd_pcm_hardware dcp_pcm_hw_unplugged = {
.period_bytes_min = 4096,
.period_bytes_max = SIZE_MAX,
.periods_min = 2,
.periods_max = UINT_MAX,
.periods_max = DCPAUD_PERIODS_MAX,
};

static int dcpaud_read_remote_info(struct dcp_audio *dcpaud)
Expand Down Expand Up @@ -311,7 +318,7 @@ static int dcp_pcm_open(struct snd_pcm_substream *substream)
hw.info = SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_MMAP_VALID |
SNDRV_PCM_INFO_INTERLEAVED;
hw.periods_min = 2;
hw.periods_max = UINT_MAX;
hw.periods_max = DCPAUD_PERIODS_MAX;
hw.period_bytes_min = 256;
hw.period_bytes_max = SIZE_MAX; // TODO dma_get_max_seg_size(dma_dev);
hw.buffer_bytes_max = SIZE_MAX;
Expand Down