[alsa-devel] [PATCH v6] ASoC: omap-mcbsp: Add PM QoS support for McBSP to prevent glitches

[Matt Ranostay]

On Wed, Jan 11, 2017 at 11:55 PM, Peter Ujfalusi <peter.ujfalusi at ti.com> wrote:
> On 01/12/2017 09:35 AM, Matt Ranostay wrote:
>> We can get audio errors if hitting deeper idle states on omaps:
>>
>> [alsa.c:230] error: Fatal problem with alsa output, error -5.
>> [audio.c:614] error: Error in writing audio (Input/output error?)!
>>
>> This seems to happen with off mode idle enabled as power for the
>> whole SoC may get cut off between filling the McBSP fifo using DMA.
>> While active DMA blocks deeper idle states in hardware, McBSP
>> activity does not seem to do so.
>>
>> Basing the QoS latency calculation on the FIFO size, threshold,
>> sample rate, and channels.
>>
>> Based on the original patch by Tony Lindgren
>> Link: https://patchwork.kernel.org/patch/9305867/
>>
>> Cc: Tony Lindgren <tony at atomide.com>
>> Cc: Peter Ujfalusi <peter.ujfalusi at ti.com>
>> Signed-off-by: Matt Ranostay <matt at ranostay.consulting>
>> ---
>> Changes from v1:
>> * add calculations for latency per number of FIFO locations
>>
>> Changes from v2:
>> * add missing mcbsp.h header change
>>
>> Changes from v3:
>> * base the latency calculations on threshold, buffer size, sample
>>   rate, and channels
>>
>> Changes from v4:
>> * using Peter Ujfalusi's suggestions for restoring a higher latency on
>> audio stream completion, or if not applicable remove the QoS request
>>
>> Changes from v5:
>> * clean up latency checking logic
>> * move logic to .prepare and .shutdown to avoid functions that can sleep
>>
>> Changes from v6:
>> * move QoS removal to asoc_mcbsp_remove from omap_mcbsp_cleanup
>
> Looks good.
>
> You can add my
> Acked-by: Peter Ujfalusi <peter.ujfalusi at ti.com>
>
> to v7...

Will do.
>
>>
>>  sound/soc/omap/mcbsp.c      |  1 +
>>  sound/soc/omap/mcbsp.h      |  3 +++
>>  sound/soc/omap/omap-mcbsp.c | 47 ++++++++++++++++++++++++++++++++++++++++++++-
>>  3 files changed, 50 insertions(+), 1 deletion(-)
>>
>> diff --git a/sound/soc/omap/mcbsp.c b/sound/soc/omap/mcbsp.c
>> index 06fec5699cc8..8fdb949a266e 100644
>> --- a/sound/soc/omap/mcbsp.c
>> +++ b/sound/soc/omap/mcbsp.c
>> @@ -25,6 +25,7 @@
>>  #include <linux/io.h>
>>  #include <linux/slab.h>
>>  #include <linux/pm_runtime.h>
>> +#include <linux/pm_qos.h>
>
> Which would not add this include line ;)
>

Good god how did I miss that? **facepalm** Will fix in the final v7 :)

>>
>>  #include <linux/platform_data/asoc-ti-mcbsp.h>
>>
>
> --
> Péter