[alsa-devel] snd_pcm_set_params faild on set_buffer_time_near and set_period_time_near
Martin Geier
martin.geier at streamunlimited.com
Fri Jul 24 13:16:44 CEST 2015
Patch with fixed name and description.
Martin
On 24.07.2015 10:21, Takashi Iwai wrote:
> On Fri, 24 Jul 2015 09:52:14 +0200,
> Martin Geier wrote:
>> Thanks for help,
>>
>> in attachment is patch with suggest change.
>> Is the patch acceptable?
> I prefer a bit clearer name like params_saved or such, but yes, it's
> what I had in my mind, too. Could you tidy it up and resubmit with
> the more description -- why it's needed and what does it? Last but
> not least, it'd be helpful if you give also signed-off-by tag.
>
>
> thanks,
>
> Takashi
>
>> Martin
>>
>> On 23.07.2015 10:11, Takashi Iwai wrote:
>>> On Tue, 21 Jul 2015 10:52:01 +0200,
>>> Martin Geier wrote:
>>>> Hallo,
>>>>
>>>> I tried to configure alsa device with snd_pcm_set_params function,
>>>> requested
>>>> parameters was:
>>>> channel 2, rate: 22050, soft_resample: 1, latency: 50000
>>>>
>>>> Function snd_pcm_hw_params_set_buffer_time_near and
>>>> snd_pcm_hw_param_set_near
>>>> is called with:
>>>> min: 50000, max: 50000, mindir: 0, maxdir: -1
>>>>
>>>> and input params was:
>>>>
>>>> ACCESS: RW_INTERLEAVED
>>>> FORMAT: S16_LE
>>>> SUBFORMAT: STD
>>>> SAMPLE_BITS: 16
>>>> FRAME_BITS: 32
>>>> CHANNELS: 2
>>>> RATE: 22050
>>>> PERIOD_TIME: (362 743039)
>>>> PERIOD_SIZE: [8 16384]
>>>> PERIOD_BYTES: [32 65536]
>>>> PERIODS: [2 19]
>>>> BUFFER_TIME: (725 1486078)
>>>> BUFFER_SIZE: [16 32768]
>>>> BUFFER_BYTES: [64 131072]
>>>> TICK_TIME: ALL
>>>>
>>>> unfortunately, this function fails, on function snd_pcm_hw_param_set_first:
>>>>
>>>> ALSA ERROR hw_params: set_near (BUFFER_TIME)
>>>> value = 50000 : Invalid argument
>>>> ACCESS: RW_INTERLEAVED
>>>> FORMAT: S16_LE
>>>> SUBFORMAT: STD
>>>> SAMPLE_BITS: 16
>>>> FRAME_BITS: 32
>>>> CHANNELS: 2
>>>> RATE: 22050
>>>> PERIOD_TIME: (4580 5533)
>>>> PERIOD_SIZE: NONE
>>>> PERIOD_BYTES: [404 488]
>>>> PERIODS: 10
>>>> BUFFER_TIME: (50022 50023)
>>>> BUFFER_SIZE: 1103
>>>> BUFFER_BYTES: 4412
>>>> TICK_TIME: ALL
>>>>
>>>> This shouldn't be problem because in snd_pcm_set_params is
>>>> snd_pcm_hw_params_set_period_time_near called.
>>>> This function should be called with same params as
>>>> snd_pcm_hw_params_set_buffer_time_near
>>>> but the input params are:
>>>>
>>>> snd_pcm_hw_param_set_near: min: 12500, max: 12500, mindir: 0, maxdir: -1
>>>> hw_params: snd_pcm_hw_param_set_near (PERIOD_TIME)
>>>> ACCESS: RW_INTERLEAVED
>>>> FORMAT: S16_LE
>>>> SUBFORMAT: STD
>>>> SAMPLE_BITS: 16
>>>> FRAME_BITS: 32
>>>> CHANNELS: 2
>>>> RATE: 22050
>>>> PERIOD_TIME: (4580 5533)
>>>> PERIOD_SIZE: NONE
>>>> PERIOD_BYTES: [404 488]
>>>> PERIODS: 10
>>>> BUFFER_TIME: (50022 50023)
>>>> BUFFER_SIZE: 1103
>>>> BUFFER_BYTES: 4412
>>>> TICK_TIME: ALL
>>>>
>>>> because in snd_pcm_hw_param_set_near is
>>>>
>>>> if (last)
>>>> err = snd_pcm_hw_param_set_last(pcm, params, var, val, dir);
>>>> else
>>>> err = snd_pcm_hw_param_set_first(pcm, params, var, val, dir);
>>>> if (err < 0)
>>>> dump_hw_params(params, "set_near", var, *val, err);
>>>> return err;
>>>>
>>>> and in error part is only debug output and not restore original parameters.
>>>>
>>>> Environment:
>>>> alsa-lib 1.0.27.1
>>>> TI AM335x soc
>>>>
>>>> Simple fix is attached, but I am not sure if it is correct.
>>> Thanks for analysis and patch. It's however rather a bug in
>>> snd_pcm_set_params(). There is no guarantee to keep the old value in
>>> snd_pcm_set_*(), thus the caller needs to take care of it instead.
>>>
>>>
>>> Takashi
>>> _______________________________________________
>>> Alsa-devel mailing list
>>> Alsa-devel at alsa-project.org
>>> http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
>> --
>> *StreamUnlimited*
>> High Tech Campus Vienna, Gutheil-Schoder-Gasse 10, A-1102 Vienna, Austria
>> Levocska 9, 851 01 Bratislava, Slovakia
>> Email: martin.geier at streamunlimited.com
>> www.streamunlimited.com
>>
>> Meet us at:
>> IFA - Berlin, 4-9 September 2015
>> HK Electronics - Hong Kong, 13-16 October 2015
>> CEDIA - Dallas, 14-17 October 2015
>> [1.2 <text/html; windows-1252 (7bit)>]
>>
>> >From 2d4e94d974678bbd4826b33c59c275d1f34edc20 Mon Sep 17 00:00:00 2001
>> From: Martin Geier <martin.geier at streamunlimited.com>
>> Date: Fri, 24 Jul 2015 09:30:57 +0200
>> Subject: [PATCH] restore hw params on set rate failed
>>
>> ---
>> pcm.c | 4 +++-
>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/src/pcm/pcm.c b/src/pcm/pcm.c
>> index ca4d416..b6de73e 100644
>> --- a/src/pcm/pcm.c
>> +++ b/src/pcm/pcm.c
>> @@ -7883,7 +7883,7 @@ int snd_pcm_set_params(snd_pcm_t *pcm,
>> int soft_resample,
>> unsigned int latency)
>> {
>> - snd_pcm_hw_params_t *params;
>> + snd_pcm_hw_params_t *params, pparams;
>> snd_pcm_sw_params_t *swparams;
>> const char *s = snd_pcm_stream_name(snd_pcm_stream(pcm));
>> snd_pcm_uframes_t buffer_size, period_size;
>> @@ -7936,9 +7936,11 @@ int snd_pcm_set_params(snd_pcm_t *pcm,
>> return -EINVAL;
>> }
>> /* set the buffer time */
>> + pparams = *params;
>> err = INTERNAL(snd_pcm_hw_params_set_buffer_time_near)(pcm, params, &latency, NULL);
>> if (err < 0) {
>> /* error path -> set period size as first */
>> + *params = pparams;
>> /* set the period time */
>> period_time = latency / 4;
>> err = INTERNAL(snd_pcm_hw_params_set_period_time_near)(pcm, params, &period_time, NULL);
>> --
>> 1.9.1
>>
--
*StreamUnlimited*
High Tech Campus Vienna, Gutheil-Schoder-Gasse 10, A-1102 Vienna, Austria
Levocska 9, 851 01 Bratislava, Slovakia
Email: martin.geier at streamunlimited.com
www.streamunlimited.com
Meet us at:
IFA - Berlin, 4-9 September 2015
HK Electronics - Hong Kong, 13-16 October 2015
CEDIA - Dallas, 14-17 October 2015
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