[alsa-devel] What is the meaning of the mask values in the pcm hw constraints struct ?

[Neil Jones]

I am developing an ASoC driver for a custom SoC (not in tree yet), I
have written the platform and board modules and my hardware detects and
installs ok, im now trying to play sound using aplay but im having
issues.

I get the error "aplay: set_params:1022: Unable to install hw params:"
I have traced the problem to a failing ioctl call
(snd_pcm_playback_ioctl) the error occurs in snd_pcm_hw_refine when
refining the mask for the SNDRV_PCM_HW_PARAM_ACCESS mask, all the bit
fields in my runtime->hw_constraints are zero for this field, but the
requested params have the value 7, Im not sure what this means, the
SNDRV_PCM_ACCESS_xxx defines in asound.h only go upto 4 ?

I have attached logs below (with RULES_DEBUG turned on) hopefully this
may shed some light.

Thanks in advance for any help,

Neil Jones


Logs:

# /usr/bin/aplay /var/snd48khz.wav
Playing WAVE '/var/snd48khz.wav' : Signed 16 bit Little Endian, Rate
48000 Hz, Stereo
aplay: set_params:1022: Unable to install hw params:
ACCESS:  RW_INTERLEAVED
FORMAT:  S16_LE
SUBFORMAT:  STD
SAMPLE_BITS: 16
FRAME_BITS: 32
CHANNELS: 2
RATE: 48000
PERIOD_TIME: (85333 85334)
PERIOD_SIZE: 4096
PERIOD_BYTES: 16384
PERIODS: (5 6)
BUFFER_TIME: 500000
BUFFER_SIZE: 24000
BUFFER_BYTES: 96000
TICK_TIME: 0

(klog)
...
Rule 0 [4030f9f4]: FORMAT = 4 -> 4
Rule 2 [4030f750]: SAMPLE_BITS = [16 16] -> [16 16]
Rule 4 [4030f90c]: FRAME_BITS = [16 16] -> [16 16]
Rule 5 [4030f90c]: FRAME_BITS = [16 16] -> [16 16]
Rule 7 [4030f90c]: RATE = [48000 48000] -> [48000 48000]
Rule 8 [4030f90c]: RATE = [48000 48000] -> [48000 48000]
Rule 9 [4030f750]: PERIODS = [1 128] -> [1 128]
Rule 10 [4030f750]: PERIOD_SIZE = [16 4096] -> [16 4096]
Rule 12 [4030f828]: PERIOD_SIZE = [16 4096] -> [16 4096]
Rule 15 [4030f828]: BUFFER_SIZE = [16 65536] -> [16 65536]
Rule 18 [4030f90c]: PERIOD_TIME = (166 128000] -> (333 85334)
Rule 19 [4030f90c]: BUFFER_TIME = (166 2048000] -> (333 1365334)
Rule 7 [4030f90c]: RATE = [48000 48000] -> [48000 48000]
Rule 8 [4030f90c]: RATE = [48000 48000] -> [48000 48000]
Rule 12 [4030f828]: PERIOD_SIZE = [16 4096] -> [16 4096]
Rule 15 [4030f828]: BUFFER_SIZE = [16 65536] -> [16 65536]
ACCESS = 0000000000000007 -> 0000000000000000
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