June 2017 - Alsa-devel - mailman.alsa-project.org

[alsa-devel] [PATCH 0/2] ASoC: da7219: Resolve HP detect issues relating to MCLK
by Adam Thomson 19 Jun '17

19 Jun '17

The patch set resolves issues in the HP detect feature, relating to MCLK, where the feature can misdetect headphones as lineout. Adam Thomson (2): ASoC: da7219: Fix HP detection procedure for all MCLK frequencies ASoC: Intel: bxt: Move codec sysclk config to codec_init function sound/soc/codecs/da7219-aad.c | 31 ++++++++++++---- sound/soc/codecs/da7219.c | 53 ++++++++++++++++++--------- sound/soc/codecs/da7219.h | 5 ++- sound/soc/intel/boards/bxt_da7219_max98357a.c | 14 ++++--- 4 files changed, 73 insertions(+), 30 deletions(-) -- 1.9.1

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[alsa-devel] [PATCH] ASoC: compress: Derive substream from stream based on direction
by bgoswami＠codeaurora.org 19 Jun '17

19 Jun '17

From: Satish Babu Patakokila <sbpata(a)codeaurora.org> Currently compress driver hardcodes direction as playback to get substream from the stream. This results in getting the incorrect substream for compressed capture usecase. To fix this, remove the hardcoding and derive substream based on the stream direction. Signed-off-by: Satish Babu Patakokila <sbpata(a)codeaurora.org> Signed-off-by: Banajit Goswami <bgoswami(a)codeaurora.org> --- sound/soc/soc-compress.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/sound/soc/soc-compress.c b/sound/soc/soc-compress.c index bfd71b8..206f36b 100644 --- a/sound/soc/soc-compress.c +++ b/sound/soc/soc-compress.c @@ -81,7 +81,8 @@ static int soc_compr_open(struct snd_compr_stream *cstream) static int soc_compr_open_fe(struct snd_compr_stream *cstream) { struct snd_soc_pcm_runtime *fe = cstream->private_data; - struct snd_pcm_substream *fe_substream = fe->pcm->streams[0].substream; + struct snd_pcm_substream *fe_substream = + fe->pcm->streams[cstream->direction].substream; struct snd_soc_platform *platform = fe->platform; struct snd_soc_dai *cpu_dai = fe->cpu_dai; struct snd_soc_dpcm *dpcm; @@ -467,7 +468,8 @@ static int soc_compr_set_params_fe(struct snd_compr_stream *cstream, struct snd_compr_params *params) { struct snd_soc_pcm_runtime *fe = cstream->private_data; - struct snd_pcm_substream *fe_substream = fe->pcm->streams[0].substream; + struct snd_pcm_substream *fe_substream = + fe->pcm->streams[cstream->direction].substream; struct snd_soc_platform *platform = fe->platform; struct snd_soc_dai *cpu_dai = fe->cpu_dai; int ret = 0, stream; -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project

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[alsa-devel] [PATCH] ASoC: zx-i2s: flip I2S master/slave mode
by Shawn Guo 19 Jun '17

19 Jun '17

From: Shawn Guo <shawn.guo(a)linaro.org> The SND_SOC_DAIFMT_MASTER bits are defined to specify the master/slave mode for Codec, not I2S. So the I2S master/slave mode should be flipped according to SND_SOC_DAIFMT_MASTER bits. Signed-off-by: Shawn Guo <shawn.guo(a)linaro.org> --- sound/soc/zte/zx-i2s.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/sound/soc/zte/zx-i2s.c b/sound/soc/zte/zx-i2s.c index dd124d5acf01..16195ee776e5 100644 --- a/sound/soc/zte/zx-i2s.c +++ b/sound/soc/zte/zx-i2s.c @@ -203,13 +203,15 @@ static int zx_i2s_set_fmt(struct snd_soc_dai *cpu_dai, unsigned int fmt) switch (fmt & SND_SOC_DAIFMT_MASTER_MASK) { case SND_SOC_DAIFMT_CBM_CFM: - i2s->master = 1; - val |= ZX_I2S_TIMING_MAST; - break; - case SND_SOC_DAIFMT_CBS_CFS: + /* Codec is master, and I2S is slave. */ i2s->master = 0; val |= ZX_I2S_TIMING_SLAVE; break; + case SND_SOC_DAIFMT_CBS_CFS: + /* Codec is slave, and I2S is master. */ + i2s->master = 1; + val |= ZX_I2S_TIMING_MAST; + break; default: dev_err(cpu_dai->dev, "Unknown master/slave format\n"); return -EINVAL; -- 1.9.1

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[alsa-devel] [PATCH] ALSA: hda: Fix potential race at unregistration and unsol events
by Takashi Iwai 19 Jun '17

19 Jun '17

When the codec device is unregistered / freed, it may release the resource while being used in an unsolicited event like the jack detection work. This leads to use-after-free. The fix here is to unregister the device at first, i.e. removing the codec from the list, then flushing the pending works to assure that all unsol events are gone. After this point, we're free from accessing the codec via unsol events, thus can release the resources gracefully. The issue was spotted originally by Intel CI, but it couldn't be reproduced reliably by its nature. So let's hope this fix really addresses the whole issues. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=196045 Reported-by: Martin Peres <martin.peres(a)free.fr> Signed-off-by: Takashi Iwai <tiwai(a)suse.de> --- sound/hda/hdac_bus.c | 1 + sound/hda/hdac_device.c | 1 + 2 files changed, 2 insertions(+) diff --git a/sound/hda/hdac_bus.c b/sound/hda/hdac_bus.c index 0e81ea89a596..714a51721a31 100644 --- a/sound/hda/hdac_bus.c +++ b/sound/hda/hdac_bus.c @@ -212,5 +212,6 @@ void snd_hdac_bus_remove_device(struct hdac_bus *bus, bus->caddr_tbl[codec->addr] = NULL; clear_bit(codec->addr, &bus->codec_powered); bus->num_codecs--; + flush_work(&bus->unsol_work); } EXPORT_SYMBOL_GPL(snd_hdac_bus_remove_device); diff --git a/sound/hda/hdac_device.c b/sound/hda/hdac_device.c index 03c9872c31cf..19deb306facb 100644 --- a/sound/hda/hdac_device.c +++ b/sound/hda/hdac_device.c @@ -159,6 +159,7 @@ void snd_hdac_device_unregister(struct hdac_device *codec) if (device_is_registered(&codec->dev)) { hda_widget_sysfs_exit(codec); device_del(&codec->dev); + snd_hdac_bus_remove_device(codec->bus, codec); } } EXPORT_SYMBOL_GPL(snd_hdac_device_unregister); -- 2.13.1

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[alsa-devel] [PATCH v3] ALSA: firewire-lib: Fix stall of process context at packet error
by Takashi Sakamoto 19 Jun '17

19 Jun '17

At Linux v3.5, packet processing can be done in process context of ALSA PCM application as well as software IRQ context for OHCI 1394. Below is an example of the callgraph (some calls are omitted). ioctl(2) with e.g. HWSYNC (sound/core/pcm_native.c) ->snd_pcm_common_ioctl1() ->snd_pcm_hwsync() ->snd_pcm_stream_lock_irq (sound/core/pcm_lib.c) ->snd_pcm_update_hw_ptr() ->snd_pcm_udpate_hw_ptr0() ->struct snd_pcm_ops.pointer() (sound/firewire/*) = Each handler on drivers in ALSA firewire stack (sound/firewire/amdtp-stream.c) ->amdtp_stream_pcm_pointer() (drivers/firewire/core-iso.c) ->fw_iso_context_flush_completions() ->struct fw_card_driver.flush_iso_completion() (drivers/firewire/ohci.c) = flush_iso_completions() ->struct fw_iso_context.callback.sc (sound/firewire/amdtp-stream.c) = in_stream_callback() or out_stream_callback() ->... ->snd_pcm_stream_unlock_irq When packet queueing error occurs or detecting invalid packets in 'in_stream_callback()' or 'out_stream_callback()', 'snd_pcm_stop_xrun()' is called on local CPU with disabled IRQ. (sound/firewire/amdtp-stream.c) in_stream_callback() or out_stream_callback() ->amdtp_stream_pcm_abort() ->snd_pcm_stop_xrun() ->snd_pcm_stream_lock_irqsave() ->snd_pcm_stop() ->snd_pcm_stream_unlock_irqrestore() The process is stalled on the CPU due to attempt to acquire recursive lock. [ 562.630853] INFO: rcu_sched detected stalls on CPUs/tasks: [ 562.630861] 2-...: (1 GPs behind) idle=37d/140000000000000/0 softirq=38323/38323 fqs=7140 [ 562.630862] (detected by 3, t=15002 jiffies, g=21036, c=21035, q=5933) [ 562.630866] Task dump for CPU 2: [ 562.630867] alsa-source-OXF R running task 0 6619 1 0x00000008 [ 562.630870] Call Trace: [ 562.630876] ? vt_console_print+0x79/0x3e0 [ 562.630880] ? msg_print_text+0x9d/0x100 [ 562.630883] ? up+0x32/0x50 [ 562.630885] ? irq_work_queue+0x8d/0xa0 [ 562.630886] ? console_unlock+0x2b6/0x4b0 [ 562.630888] ? vprintk_emit+0x312/0x4a0 [ 562.630892] ? dev_vprintk_emit+0xbf/0x230 [ 562.630895] ? do_sys_poll+0x37a/0x550 [ 562.630897] ? dev_printk_emit+0x4e/0x70 [ 562.630900] ? __dev_printk+0x3c/0x80 [ 562.630903] ? _raw_spin_lock+0x20/0x30 [ 562.630909] ? snd_pcm_stream_lock+0x31/0x50 [snd_pcm] [ 562.630914] ? _snd_pcm_stream_lock_irqsave+0x2e/0x40 [snd_pcm] [ 562.630918] ? snd_pcm_stop_xrun+0x16/0x70 [snd_pcm] [ 562.630922] ? in_stream_callback+0x3e6/0x450 [snd_firewire_lib] [ 562.630925] ? handle_ir_packet_per_buffer+0x8e/0x1a0 [firewire_ohci] [ 562.630928] ? ohci_flush_iso_completions+0xa3/0x130 [firewire_ohci] [ 562.630932] ? fw_iso_context_flush_completions+0x15/0x20 [firewire_core] [ 562.630935] ? amdtp_stream_pcm_pointer+0x2d/0x40 [snd_firewire_lib] [ 562.630938] ? pcm_capture_pointer+0x19/0x20 [snd_oxfw] [ 562.630943] ? snd_pcm_update_hw_ptr0+0x47/0x3d0 [snd_pcm] [ 562.630945] ? poll_select_copy_remaining+0x150/0x150 [ 562.630947] ? poll_select_copy_remaining+0x150/0x150 [ 562.630952] ? snd_pcm_update_hw_ptr+0x10/0x20 [snd_pcm] [ 562.630956] ? snd_pcm_hwsync+0x45/0xb0 [snd_pcm] [ 562.630960] ? snd_pcm_common_ioctl1+0x1ff/0xc90 [snd_pcm] [ 562.630962] ? futex_wake+0x90/0x170 [ 562.630966] ? snd_pcm_capture_ioctl1+0x136/0x260 [snd_pcm] [ 562.630970] ? snd_pcm_capture_ioctl+0x27/0x40 [snd_pcm] [ 562.630972] ? do_vfs_ioctl+0xa3/0x610 [ 562.630974] ? vfs_read+0x11b/0x130 [ 562.630976] ? SyS_ioctl+0x79/0x90 [ 562.630978] ? entry_SYSCALL_64_fastpath+0x1e/0xad This commit fixes the above bug. This assumes two cases: 1. Any error is detected in software IRQ context of OHCI 1394 context. In this case, PCM substream should be aborted in packet handler. On the other hand, it should not be done in any process context. TO distinguish these two context, use 'in_interrupt()' macro. 2. Any error is detect in process context of ALSA PCM application. In this case, PCM substream should not be aborted in packet handler because PCM substream lock is acquired. The task to abort PCM substream should be done in ALSA PCM core. For this purpose, SNDRV_PCM_POS_XRUN is returned at 'struct snd_pcm_ops.pointer()'. Suggested-by: Clemens Ladisch <clemens(a)ladisch.de> Fixes: e9148dddc3c7("ALSA: firewire-lib: flush completed packets when reading PCM position") Cc: <stable(a)vger.kernel.org> # 4.9+ Signed-off-by: Takashi Sakamoto <o-takashi(a)sakamocchi.jp> --- sound/firewire/amdtp-stream.c | 8 ++++++-- sound/firewire/amdtp-stream.h | 2 +- 2 files changed, 7 insertions(+), 3 deletions(-) diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c index 9678bc75dc5b..3fc581a5ad62 100644 --- a/sound/firewire/amdtp-stream.c +++ b/sound/firewire/amdtp-stream.c @@ -701,7 +701,9 @@ static void out_stream_callback(struct fw_iso_context *context, u32 tstamp, cycle = increment_cycle_count(cycle, 1); if (s->handle_packet(s, 0, cycle, i) < 0) { s->packet_index = -1; - amdtp_stream_pcm_abort(s); + if (in_interrupt()) + amdtp_stream_pcm_abort(s); + WRITE_ONCE(s->pcm_buffer_pointer, SNDRV_PCM_POS_XRUN); return; } } @@ -753,7 +755,9 @@ static void in_stream_callback(struct fw_iso_context *context, u32 tstamp, /* Queueing error or detecting invalid payload. */ if (i < packets) { s->packet_index = -1; - amdtp_stream_pcm_abort(s); + if (in_interrupt()) + amdtp_stream_pcm_abort(s); + WRITE_ONCE(s->pcm_buffer_pointer, SNDRV_PCM_POS_XRUN); return; } diff --git a/sound/firewire/amdtp-stream.h b/sound/firewire/amdtp-stream.h index 6d613f2eb612..ed6eafd10992 100644 --- a/sound/firewire/amdtp-stream.h +++ b/sound/firewire/amdtp-stream.h @@ -135,7 +135,7 @@ struct amdtp_stream { /* For a PCM substream processing. */ struct snd_pcm_substream *pcm; struct tasklet_struct period_tasklet; - unsigned int pcm_buffer_pointer; + snd_pcm_uframes_t pcm_buffer_pointer; unsigned int pcm_period_pointer; /* To wait for first packet. */ -- 2.11.0

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[alsa-devel] [PATCH v3] ALSA: core: let low-level driver or userspace disable rewinds
by Subhransu S. Prusty 19 Jun '17

19 Jun '17

From: Pierre-Louis Bossart <pierre-louis.bossart(a)linux.intel.com> Add new hw_params flag to explicitly tell driver that rewinds will never be used. This can be used by low-level driver to optimize DMA operations and reduce power consumption. Use this flag only when data written in ring buffer will never be invalidated, e.g. any update of appl_ptr is final. Note that the update of appl_ptr include both a read/write data operation as well as snd_pcm_forward() whose behavior is not modified. Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart(a)linux.intel.com> Signed-off-by: Ramesh Babu <ramesh.babu(a)intel.com> Signed-off-by: Subhransu S. Prusty <subhransu.s.prusty(a)intel.com> --- v2 -> v3 return error for rewind operation if no_rewinds set. include/sound/pcm.h | 1 + include/uapi/sound/asound.h | 1 + sound/core/pcm_native.c | 8 ++++++++ 3 files changed, 10 insertions(+) diff --git a/include/sound/pcm.h b/include/sound/pcm.h index 79fedf517070..c1e2b87cd409 100644 --- a/include/sound/pcm.h +++ b/include/sound/pcm.h @@ -368,6 +368,7 @@ struct snd_pcm_runtime { unsigned int rate_num; unsigned int rate_den; unsigned int no_period_wakeup: 1; + unsigned int no_rewinds:1; /* -- SW params -- */ int tstamp_mode; /* mmap timestamp is updated */ diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h index fd41697cb4d3..c697ff90450d 100644 --- a/include/uapi/sound/asound.h +++ b/include/uapi/sound/asound.h @@ -365,6 +365,7 @@ struct snd_pcm_info { #define SNDRV_PCM_HW_PARAMS_NORESAMPLE (1<<0) /* avoid rate resampling */ #define SNDRV_PCM_HW_PARAMS_EXPORT_BUFFER (1<<1) /* export buffer */ #define SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP (1<<2) /* disable period wakeups */ +#define SNDRV_PCM_HW_PARAMS_NO_REWINDS (1<<3) /* disable rewinds */ struct snd_interval { unsigned int min, max; diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index bf5d0f2acfb9..6769f4751fa0 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -554,6 +554,8 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream, runtime->no_period_wakeup = (params->info & SNDRV_PCM_INFO_NO_PERIOD_WAKEUP) && (params->flags & SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP); + runtime->no_rewinds = + (params->flags & SNDRV_PCM_HW_PARAMS_NO_REWINDS) ? 1 : 0; bits = snd_pcm_format_physical_width(runtime->format); runtime->sample_bits = bits; @@ -2521,6 +2523,9 @@ static snd_pcm_sframes_t snd_pcm_playback_rewind(struct snd_pcm_substream *subst if (frames == 0) return 0; + if (runtime->no_rewinds) + return -ENODEV; + snd_pcm_stream_lock_irq(substream); ret = do_pcm_hwsync(substream); if (!ret) @@ -2539,6 +2544,9 @@ static snd_pcm_sframes_t snd_pcm_capture_rewind(struct snd_pcm_substream *substr if (frames == 0) return 0; + if (runtime->no_rewinds) + return -ENODEV; + snd_pcm_stream_lock_irq(substream); ret = do_pcm_hwsync(substream); if (!ret) -- 1.9.1

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[alsa-devel] [RFC][PATCH] ALSA: pcm: introduce ACK_APPLPTR flag and bump up interface version to v2.0.14
by Takashi Sakamoto 19 Jun '17

19 Jun '17

Hi, This patchset includes commits for both kernel/user land for an issue addressed in this message thread[1]. In a development period for v4.13, it's clear that there's a type of devices which demand userspace applications to change their behaviour. These devices can take care of application-side pointer on PCM buffer for their data transmission. As a result, these devices achieve some advantages. For these devices, drivers need to get feedback about current position of the pointer from applications when they queue/dequeue PCM frames on the buffer. ALSA PCM core partly assist the above design. The core can call a handler in driver side when applications operate PCM frames by ioctl(2) with SNDRV_PCM_IOCTL_[READ|WRITE][N|I] command. However, when operating for mapped PCM buffer, it can't assist applications for the above design. In this scenario, applications should call ioctl(2) with SNDRV_PCM_IOCTL_SYNC_PTR after handle any PCM frames on the buffer. This patchset bumps up interface version with new info flag to notify the above change to user land developers. This patchset is written with below ideas: 1. Stuffs in user land can tell their assists for the above design to kernel land by using hw_param flag. When they don't assist, they see on hw_params data that mmap operation is not supported. 2. Drivers can acknowledge the above flag. When registering appropriate PCM rules in advance, they can calculate values for each parameters in both cases that stuffs in user land can/cannot assist it. This is useful for packet-oriented drivers to judge utilizing any interrupt context for packetization. 3. This is device-specific issue, independently of platform architecture. On x86/ppc/alpha platforms, status/control data of PCM substream is still available in process' VMA of application via page frame mapping. [1] http://mailman.alsa-project.org/pipermail/alsa-devel/2017-June/121438.html For kernel land: Takashi Sakamoto (1): ALSA: pcm: introduce ACK_APPLPTR flag and bump up interface version to 2.0.14 include/uapi/sound/asound.h | 11 ++++++++++- sound/core/pcm_native.c | 25 +++++++++++++++++++++++++ 2 files changed, 35 insertions(+), 1 deletion(-) For user land: Takashi Sakamoto (2): ALSA: pcm: introduce ACK_APPLPTR flag and bump up interface version to 2.0.14 pcm: add support for interface version 2.0.14 include/sound/asound.h | 11 ++++++++++- src/pcm/pcm_hw.c | 43 +++++++++++++++++++++++++++++++++++++------ 2 files changed, 47 insertions(+), 7 deletions(-) -- 2.11.0

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[alsa-devel] [PATCH] ALSA: pcm: Fix possible inconsistent appl_ptr update via mmap
by Takashi Iwai 19 Jun '17

19 Jun '17

The ALSA PCM core refers to the appl_ptr value stored on the mmapped page that is shared between kernel and user-space. Although the reference is performed in the PCM stream lock, it doesn't guarantee the atomic access when the value gets updated concurrently from the user-space on another CPU. In most of codes, this is no big problem, but still there are a few places that may result in slight inconsistencies because they access runtime->control->appl_ptr multiple times; that is, the second read might be a different value from the first value. It can be even backward or jumping, as we have no control for it. Hence, the calculation may give an unexpected value. Luckily, there is no security vulnerability by that, as far as I've checked. But still we should address it. This patch tries to reduce such possible cases. The fix is simple -- we just read once, store it to a local variable and use it for the rest calculations. Signed-off-by: Takashi Iwai <tiwai(a)suse.de> --- sound/core/pcm_lib.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index 631cd598ba6c..cda258d91490 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -65,15 +65,16 @@ void snd_pcm_playback_silence(struct snd_pcm_substream *substream, snd_pcm_ufram if (runtime->silence_size < runtime->boundary) { snd_pcm_sframes_t noise_dist, n; - if (runtime->silence_start != runtime->control->appl_ptr) { - n = runtime->control->appl_ptr - runtime->silence_start; + snd_pcm_uframes_t appl_ptr = runtime->control->appl_ptr; + if (runtime->silence_start != appl_ptr) { + n = appl_ptr - runtime->silence_start; if (n < 0) n += runtime->boundary; if ((snd_pcm_uframes_t)n < runtime->silence_filled) runtime->silence_filled -= n; else runtime->silence_filled = 0; - runtime->silence_start = runtime->control->appl_ptr; + runtime->silence_start = appl_ptr; } if (runtime->silence_filled >= runtime->buffer_size) return; @@ -2224,7 +2225,9 @@ snd_pcm_sframes_t __snd_pcm_lib_xfer(struct snd_pcm_substream *substream, continue; /* draining */ } frames = size > avail ? avail : size; - cont = runtime->buffer_size - runtime->control->appl_ptr % runtime->buffer_size; + appl_ptr = runtime->control->appl_ptr; + appl_ofs = appl_ptr % runtime->buffer_size; + cont = runtime->buffer_size - appl_ofs; if (frames > cont) frames = cont; if (snd_BUG_ON(!frames)) { @@ -2232,8 +2235,6 @@ snd_pcm_sframes_t __snd_pcm_lib_xfer(struct snd_pcm_substream *substream, snd_pcm_stream_unlock_irq(substream); return -EINVAL; } - appl_ptr = runtime->control->appl_ptr; - appl_ofs = appl_ptr % runtime->buffer_size; snd_pcm_stream_unlock_irq(substream); err = writer(substream, appl_ofs, data, offset, frames, transfer); -- 2.13.1

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[alsa-devel] [PATCH 0/7] ASoC: stm32: sai: misc fixes
by olivier moysan 19 Jun '17

19 Jun '17

This patch-set gathers various fixes on STM32 SAI driver. olivier moysan (7): dt-bindings: stm32: sai: fix DT example ASoC: stm32: change SAI configuration flag ASoC: stm32: sai: typo fixes ASoC: stm32: sai: remove spurious trace ASoC: stm32: sai: change stop sequence ASoC: stm32: sai: fix clock management ASoC: stm32: sai: manage master clock .../devicetree/bindings/sound/st,stm32-sai.txt | 25 ++++------ sound/soc/stm/Kconfig | 10 ++-- sound/soc/stm/Makefile | 4 +- sound/soc/stm/stm32_sai.c | 2 +- sound/soc/stm/stm32_sai.h | 1 - sound/soc/stm/stm32_sai_sub.c | 57 +++++++++++++--------- 6 files changed, 54 insertions(+), 45 deletions(-) -- 1.9.1

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[alsa-devel] MIDI Clock issue when aconnect multiple times to same device.
by Allan Klinbail 19 Jun '17

19 Jun '17

Hi All, I have noticed an issue with the handling of MIDI clock when making multiple connections to and from the same device.. Specifically with EMAGIC AMT-8 and Unitor 8 Mk2 (I can't confirm it is happening for other devices). The scenario is MIDI Port 1 is receiving MIDI clock along with note information for devices on ports 2 & 3 .. (in this scenario sending at 120 BPM) The MIDI clock signal is automatically distributed by the device to all other ports. When connecting Input 1 to output 2 (to send MIDI from the first external device to the second).. The MIDI clock appears to be retransmitted a second time.. the device on port 2 then believes it is receiving a clock signal at approximately 168 BPM. This signal is not stable When connecting input 1 to output 3 the MIDI clock seems to be distributed another time to the EMAGIC .. which is now sending out an even more unstable clock signal at approximate 189 BPM.. It is possible to filter physical inputs from receiving MIDI Clock or outputs from sending. This does not solve this issue (Filtering the input stops the clock altogether, filtering the output stops it from being received by the desired device) However it is not possible to filter the messaging going to to the unit from a connection established with aconnect (or using tools like qjackctl). I am not sure if it is possible to fix the driver for this issue,especially if the MIDI clock source is external. However, I thought it best to alert you to this situation. thanks Allan

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