Re: [PATCH v2 4/6] kselftest/alsa: mixer-test: Skip write verification for volatile controls

[Takashi Iwai <tiwai@xxxxxxx>]

On Fri, 14 Jun 2024 17:57:37 +0200,
Mark Brown wrote:
> 
> On Fri, Jun 14, 2024 at 05:37:13PM +0200, Takashi Iwai wrote:
> 
> > @@ -616,6 +616,10 @@ static int write_and_verify(struct ctl_data *ctl,
> >  	if (!snd_ctl_elem_info_is_readable(ctl->info))
> >  		return err;
> >  
> > +	/* Skip the verification for volatile controls, too */
> > +	if (snd_ctl_elem_info_is_volatile(ctl->info))
> > +		return err;
> > +
> 
> I think we should do the checks in test_ctl_get_value() still - a read
> and then ctl_value_is_valid() on whatever we read.  It doesn't need to
> match the value we wrote but it should still be valid for the control.

So something like below?


Takashi

-- 8< --
From: Takashi Iwai <tiwai@xxxxxxx>
Subject: [PATCH v3] kselftest/alsa: mixer-test: Allow value mismatch for volatile controls

The control elements with volatile flag don't guarantee that the
written values are actually saved for the next reads, hence we can't
verify the written values reliably.  Return as success for volatile
controls even if the value verification after writes fails, in order
to avoid false-positive.

Reported-by: Paul Menzel <pmenzel@xxxxxxxxxxxxx>
Closes: https://lore.kernel.org/r/1d44be36-9bb9-4d82-8953-5ae2a4f09405@xxxxxxxxxxxxx
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
 tools/testing/selftests/alsa/mixer-test.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/testing/selftests/alsa/mixer-test.c b/tools/testing/selftests/alsa/mixer-test.c
index 1c04e5f638a0..62b77737f0de 100644
--- a/tools/testing/selftests/alsa/mixer-test.c
+++ b/tools/testing/selftests/alsa/mixer-test.c
@@ -668,6 +668,10 @@ static int write_and_verify(struct ctl_data *ctl,
 		ksft_print_msg("%s read and written values differ\n",
 			       ctl->name);
 
+	/* Allow difference for volatile controls */
+	if (snd_ctl_elem_info_is_volatile(ctl->info))
+		return 0;
+
 	return -1;
 }
 
-- 
2.43.0