[alsa-devel] Async ops SOC compress issue

[b_lkasam at codeaurora.org]

Hi ALSA team,
Need inputs wrt one issue seen with soc-compress code.

Please help check below issue seen in soc-compress file wrt handling 
multiple BEs
with async ops ASYNC_DPCM_SND_SOC_HW_PARAMS set for given FE dailink/BE 
dailinks also.

Issue :
pcm_prepare failure when 2 BE's on same FE enabled during compress 
playback,
seen only when both BE's have SOC_HW_PARAM defined as an async_op.

Analysis:
- With SOC_HW_PARAMS defined as async_op on both BE's,
hw_params api for both of these BE's are scheduled for asynchronous 
execution.

- It is observed that dpcm_be_hw_params_prepare is getting invoked 
twice, but for the same BE.

Below are the issue logs taken for above scenario.

12-21 16:38:32.074     0     0 D SDM660 Compress1: connected new DPCM 
playback path SDM660 Compress1 -> INT4_MI2S_RX
12-21 16:38:32.075     0     0 D SDM660 Compress1: connected new DPCM 
playback path SDM660 Compress1 -> INT0_MI2S_RX

12-21 16:38:32.075     0     0 D INT0_MI2S_RX: ASoC: open playback BE 
INT0_MI2S_RX
12-21 16:38:32.076     0     0 D INT4_MI2S_RX: ASoC: open playback BE 
INT4_MI2S_RX

12-21 16:38:32.077     0     0 E soc_compr_set_params_fe: : async 
schedule hw_params for be INT0_MI2S_RX
12-21 16:38:32.077     0     0 E soc_compr_set_params_fe: : async 
schedule hw_params for be INT4_MI2S_RX

12-21 16:38:32.078     0     0 E dpcm_be_hw_params_prepare: : BE 
INT4_MI2S_RX -> dpcm_fe_dai_hw_params_be
12-21 16:38:32.079     0     0 E msm-dai-q6-mi2s soc: 
qcom,msm-dai-mi2s:qcom,msm-dai-q6-int-mi2s4: msm_dai_q6_mi2s_hw_params: 
dai id 11 dai_data->channels = 1

12-21 16:38:32.143     0     0 E dpcm_be_hw_params_prepare: : BE 
INT4_MI2S_RX -> dpcm_fe_dai_hw_params_be
12-21 16:38:32.173     0     0 E msm-dai-q6-mi2s soc: 
qcom,msm-dai-mi2s:qcom,msm-dai-q6-int-mi2s4: msm_dai_q6_mi2s_hw_params: 
ERROR    dai id 11 dai_data->channels = 1

It is not clear why dpcm_be_hw_params_prepare is happening for same BE 
twice even though async schedule was done for both.

- With async_synchronize call after scheduling of hw_param, the behavior 
is as expected.
hw_param for both BE's are success.


diff --git a/sound/soc/soc-compress.c b/sound/soc/soc-compress.c
index ad3cc68..b0a1995 100644
--- a/sound/soc/soc-compress.c
+++ b/sound/soc/soc-compress.c
@@ -535,6 +535,7 @@ static int soc_compr_set_params_fe(struct 
snd_compr_stream *cstream,
                                 }
                         }
                 }
+               async_synchronize_full_domain(&async_domain); - Adding 
this code fixing the issue, but looks not correct way, please suggest
                 for (i = 0; i < j; i++) {
                         cstream->be = be_list[i];
                         dpcm_be_hw_params_prepare(cstream);



With regards
Laxminath Kasam