[alsa-devel] Possible problem with snd_pcm_oss_sync()

[Timur Tabi]

-------- Original Message --------
Subject: 	RE: Regarding MPC8610 BSP question and issue
Date: 	Tue, 20 May 2008 08:55:46 -0700
From: 	Hayasaka Manabu <manabu.hayasaka at freescale.com>
To: 	Hayasaka Manabu <manabu.hayasaka at freescale.com>, Johnson Kelly
<Kelly.Johnson at freescale.com>
CC: 	sun york <yorksun at freescale.com>, Namiki Ayumi
<namiki at freescale.com>, Beck Glenn <Glenn.Beck at freescale.com>, Cox Kevin
<K.Cox at freescale.com>, Hamano Masahiro <M.Hamano at freescale.com>, Tabi
Timur <timur at freescale.com>
References:
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<4807899D.3000901 at freescale.com>
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<48110FCF.7070302 at freescale.com>
<BD243C8D8F65694A966948E9D51F9815C29409 at zja67exm21.fsl.freescale.net>
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<482B1D10.7090402 at freescale.com> <482B2699.8020409 at freescale.com>

I'm working with a customer that has discovered a possible problem with OSS
emulation.  Unfortunately, I don't have a lot of experience with OSS, so I need
help understanding whether the customer's observations point to a real problem
or not.

The customer is using an old application called "bplay" to test OSS audio
support on our hardware.  The application works fine on x86, but fails on our
PowerPC board.  It could be an endian issue, but I doubt it.

Here is the forwarded email (slightly edited).  Can someone familiar with the
OSS "sync" functionality comment?

---------------

They reported that it seemed some ioctl commands in the OSS emulation did not
work correctly.

The tested procedure of the ioctl commands are as following,

#1) Stopped audio stream output after doing followings:
1. Opening /dev/mixer
2. Getting a channel value (0x00000001) that is used for "ioctl(fd,
SOUND_MIXER_READ_DEVMASK, &Sndsts);".
3. Write audio volume information by "ioctl(fd,
SOUND_MIXER_WRITE_VOLUME, &Value);",

#2) Stopped audio stream output after doing following:
1. Opening /dev/dsp
2. Executing command "ioctl(fd, SNDCTL_DSP_SYNC, NULL);",

XXXX found that by commenting out the "sync_audio" function on the source
code of "bplay" made "bplay" work. So XXXX suspects the implementation of the
ioctl on the OSS emulation may have a problem.

-- 
Timur Tabi
Linux kernel developer at Freescale