Re: [PATCH v3] ALSA: control: Verify put() result when in debug mode

[Cezary Rojewski <cezary.rojewski@intel.com>]

On 2026-02-06 1:28 PM, Takashi Iwai wrote:
> On Fri, 06 Feb 2026 12:32:50 +0100,
> Cezary Rojewski wrote:
>>
>> The put() operation is expected to return:
>> 1) 0 on success if no changes were made
>> 2) 1 on success if changes were made
>> 3) error code otherwise

...

> Also, this message doesn't show any relevant information about which
> card, device and which control caused the error, and that makes
> debugging harder.  Put some prefix to identify the problematic
> control.

Quick peak to what I'm currently logging - output from 'cat trace':


#           TASK-PID     CPU#  |||||  TIMESTAMP  FUNCTION
#              | |         |   |||||     |         |
           amixer-1177    [003] .....    97.421022: snd_ctl_put_success: 
expected=0, actual=0 for ctl "Master Playback Volume" of numid=1 from 
dev="bdw_rt286", card="broadwell-rt286"

           amixer-1181    [003] .....    99.065279: snd_ctl_put_success: 
expected=1, actual=1 for ctl "Master Playback Volume" of numid=1 from 
dev="bdw_rt286", card="broadwell-rt286"

           amixer-1185    [003] .....   144.007205: snd_ctl_put_fail: 
expected=1, actual=0 for ctl "Loopback Mute" of numid=5 from 
dev="bdw_rt286", card="broadwell-rt286"


The format for trace_snd_ctl_put event class:

         TP_printk("expected=%d, actual=%d for ctl \"%s\" of numid=%d 
from dev=\"%s\", card=\"%s\"\n",
                   __entry->expected, __entry->actual,
                   __get_str(kname), __entry->numid,
                   __get_str(dname), __get_str(cname))


kname = kctl->id.name
dname = dev_name(card->dev)
cname = shortname or longname, shortname prio

Is there something still to be added?