On Sat, Aug 31, 2013 at 08:14:14PM +0100, Russell King - ARM Linux wrote:

On Sat, Aug 31, 2013 at 05:28:26PM +0200, Lars-Peter Clausen wrote:

quoted

On 08/31/2013 02:34 PM, Russell King - ARM Linux wrote:
[...]

quoted

The same conditions apply as per my previous posting - the DAI link
needs to be setup and the associated DAPM routes to tell the CPU DAI
which outputs are in use, like this:

DAI link:
                .name = "S/PDIF1",
                .stream_name = "IEC958 Playback",
                .platform_name = "mvebu-audio.1",
                .cpu_dai_name = "mvebu-audio.1",
                .codec_dai_name = "dit-hifi",
                .codec_name = "spdif-dit",

static const struct snd_soc_dapm_route routes[] = {
        { "Playback", NULL, "spdifdo" },
};

This is still not exactly the right way to implement this though. Add a
second DAI to your CPU driver, like this:

What you're suggesting is the DPCM solution.

That would be fine _if_ it works, which it doesn't.  Not only does it
cause the kernel to spit out various warnings (caused by the creation
of multiple procfs files with the same name) but it also causes a kernel
oops when VLC tries to use it (due to NULL ops in the ALSA PCM.)

Here's the warning I get - I've left the syslog stamp in these as
evidence for how long this has been known - and I reported these to
Mark when I found them:

Aug 10 15:17:18 cubox kernel: WARNING: at /home/rmk/git/linux-cubox/fs/proc/generic.c:356 proc_register+0xac/0x128()
Aug 10 15:17:18 cubox kernel: proc_dir_entry 'asound/oss' already registered
Aug 10 15:17:18 cubox kernel: Modules linked in: snd_soc_spdif_tx m25p80 orion_wdt mtd snd_soc_kirkwood snd_soc_kirkwood_spdif
Aug 10 15:17:18 cubox kernel: CPU: 0 PID: 388 Comm: kworker/u2:2 Not tainted 3.10.0+ #645
Aug 10 15:17:18 cubox kernel: Workqueue: deferwq deferred_probe_work_func
Aug 10 15:17:18 cubox kernel: [<c0013d7c>] (unwind_backtrace+0x0/0xf8) from [<c0011bec>] (show_stack+0x10/0x14)
Aug 10 15:17:18 cubox kernel: [<c0011bec>] (show_stack+0x10/0x14) from [<c0048b80>] (warn_slowpath_common+0x4c/0x68)
Aug 10 15:17:18 cubox kernel: [<c0048b80>] (warn_slowpath_common+0x4c/0x68) from [<c0048c30>] (warn_slowpath_fmt+0x30/0x40)
Aug 10 15:17:18 cubox kernel: [<c0048c30>] (warn_slowpath_fmt+0x30/0x40) from [<c0124804>] (proc_register+0xac/0x128)
Aug 10 15:17:18 cubox kernel: [<c0124804>] (proc_register+0xac/0x128) from [<c0124910>] (proc_create_data+0x90/0xac)
Aug 10 15:17:18 cubox kernel: [<c0124910>] (proc_create_data+0x90/0xac) from [<c0302b48>] (snd_info_register+0x54/0xf0)
Aug 10 15:17:18 cubox kernel: [<c0302b48>] (snd_info_register+0x54/0xf0) from [<c03190e8>] (snd_pcm_oss_register_minor+0xcc/0x1cc)
Aug 10 15:17:18 cubox kernel: [<c03190e8>] (snd_pcm_oss_register_minor+0xcc/0x1cc) from [<c030bdec>] (snd_pcm_dev_register+0x1ac/0x290)
Aug 10 15:17:18 cubox kernel: [<c030bdec>] (snd_pcm_dev_register+0x1ac/0x290) from [<c03069c8>] (snd_device_register_all+0x40/0x80)
Aug 10 15:17:18 cubox kernel: [<c03069c8>] (snd_device_register_all+0x40/0x80) from [<c030192c>] (snd_card_register+0x24/0x228)
Aug 10 15:17:18 cubox kernel: [<c030192c>] (snd_card_register+0x24/0x228) from [<c03252a4>] (snd_soc_instantiate_card+0x7b4/0x868)
Aug 10 15:17:18 cubox kernel: [<c03252a4>] (snd_soc_instantiate_card+0x7b4/0x868) from [<c03255c4>] (snd_soc_register_card+0x26c/0x324)
Aug 10 15:17:18 cubox kernel: [<c03255c4>] (snd_soc_register_card+0x26c/0x324) from [<bf00c0b4>] (kirkwood_spdif_probe+0x88/0xd8 [snd_soc_kirkwood_spdif])
Aug 10 15:17:18 cubox kernel: [<bf00c0b4>] (kirkwood_spdif_probe+0x88/0xd8 [snd_soc_kirkwood_spdif]) from [<c0259468>] (platform_drv_probe+0x18/0x1c)
Aug 10 15:17:18 cubox kernel: [<c0259468>] (platform_drv_probe+0x18/0x1c) from [<c0258144>] (really_probe+0x74/0x1f4)
Aug 10 15:17:18 cubox kernel: [<c0258144>] (really_probe+0x74/0x1f4) from [<c02583d8>] (driver_probe_device+0x30/0x48)
Aug 10 15:17:18 cubox kernel: [<c02583d8>] (driver_probe_device+0x30/0x48) from [<c0256a48>] (bus_for_each_drv+0x60/0x8c)
Aug 10 15:17:18 cubox kernel: [<c0256a48>] (bus_for_each_drv+0x60/0x8c) from [<c0258368>] (device_attach+0x80/0xa4)
Aug 10 15:17:18 cubox kernel: [<c0258368>] (device_attach+0x80/0xa4) from [<c02577a8>] (bus_probe_device+0x88/0xac)
Aug 10 15:17:18 cubox kernel: [<c02577a8>] (bus_probe_device+0x88/0xac) from [<c0257c34>] (deferred_probe_work_func+0x6c/0x9c)
Aug 10 15:17:18 cubox kernel: [<c0257c34>] (deferred_probe_work_func+0x6c/0x9c) from [<c0060a74>] (process_one_work+0x190/0x3f4)
Aug 10 15:17:18 cubox kernel: [<c0060a74>] (process_one_work+0x190/0x3f4) from [<c0062544>] (worker_thread+0xf4/0x318)
Aug 10 15:17:18 cubox kernel: [<c0062544>] (worker_thread+0xf4/0x318) from [<c006800c>] (kthread+0xa8/0xb4)
Aug 10 15:17:18 cubox kernel: [<c006800c>] (kthread+0xa8/0xb4) from [<c000e4a8>] (ret_from_fork+0x14/0x2c)
Aug 10 15:17:18 cubox kernel: ---[ end trace 174d2956b4f53cd5 ]---
Aug 10 15:17:18 cubox kernel: ------------[ cut here ]------------
Aug 10 15:17:18 cubox kernel: WARNING: at /home/rmk/git/linux-cubox/fs/proc/generic.c:356 proc_register+0xac/0x128()
Aug 10 15:17:18 cubox kernel: proc_dir_entry 'asound/oss' already registered
Aug 10 15:17:18 cubox kernel: Modules linked in: snd_soc_spdif_tx m25p80 orion_wdt mtd snd_soc_kirkwood snd_soc_kirkwood_spdif
Aug 10 15:17:18 cubox kernel: CPU: 0 PID: 388 Comm: kworker/u2:2 Tainted: G   W    3.10.0+ #645
Aug 10 15:17:18 cubox kernel: Workqueue: deferwq deferred_probe_work_func
Aug 10 15:17:18 cubox kernel: [<c0013d7c>] (unwind_backtrace+0x0/0xf8) from [<c0011bec>] (show_stack+0x10/0x14)
Aug 10 15:17:18 cubox kernel: [<c0011bec>] (show_stack+0x10/0x14) from [<c0048b80>] (warn_slowpath_common+0x4c/0x68)
Aug 10 15:17:18 cubox kernel: [<c0048b80>] (warn_slowpath_common+0x4c/0x68) from [<c0048c30>] (warn_slowpath_fmt+0x30/0x40)
Aug 10 15:17:18 cubox kernel: [<c0048c30>] (warn_slowpath_fmt+0x30/0x40) from [<c0124804>] (proc_register+0xac/0x128)
Aug 10 15:17:18 cubox kernel: [<c0124804>] (proc_register+0xac/0x128) from [<c0124910>] (proc_create_data+0x90/0xac)
Aug 10 15:17:18 cubox kernel: [<c0124910>] (proc_create_data+0x90/0xac) from [<c0302b48>] (snd_info_register+0x54/0xf0)
Aug 10 15:17:18 cubox kernel: [<c0302b48>] (snd_info_register+0x54/0xf0) from [<c03190e8>] (snd_pcm_oss_register_minor+0xcc/0x1cc)
Aug 10 15:17:18 cubox kernel: [<c03190e8>] (snd_pcm_oss_register_minor+0xcc/0x1cc) from [<c030bdec>] (snd_pcm_dev_register+0x1ac/0x290)
Aug 10 15:17:18 cubox kernel: [<c030bdec>] (snd_pcm_dev_register+0x1ac/0x290) from [<c03069c8>] (snd_device_register_all+0x40/0x80)
Aug 10 15:17:18 cubox kernel: [<c03069c8>] (snd_device_register_all+0x40/0x80) from [<c030192c>] (snd_card_register+0x24/0x228)
Aug 10 15:17:18 cubox kernel: [<c030192c>] (snd_card_register+0x24/0x228) from [<c03252a4>] (snd_soc_instantiate_card+0x7b4/0x868)
Aug 10 15:17:18 cubox kernel: [<c03252a4>] (snd_soc_instantiate_card+0x7b4/0x868) from [<c03255c4>] (snd_soc_register_card+0x26c/0x324)
Aug 10 15:17:18 cubox kernel: [<c03255c4>] (snd_soc_register_card+0x26c/0x324) from [<bf00c0b4>] (kirkwood_spdif_probe+0x88/0xd8 [snd_soc_kirkwood_spdif])
Aug 10 15:17:18 cubox kernel: [<bf00c0b4>] (kirkwood_spdif_probe+0x88/0xd8 [snd_soc_kirkwood_spdif]) from [<c0259468>] (platform_drv_probe+0x18/0x1c)
Aug 10 15:17:18 cubox kernel: [<c0259468>] (platform_drv_probe+0x18/0x1c) from [<c0258144>] (really_probe+0x74/0x1f4)
Aug 10 15:17:18 cubox kernel: [<c0258144>] (really_probe+0x74/0x1f4) from [<c02583d8>] (driver_probe_device+0x30/0x48)
Aug 10 15:17:18 cubox kernel: [<c02583d8>] (driver_probe_device+0x30/0x48) from [<c0256a48>] (bus_for_each_drv+0x60/0x8c)
Aug 10 15:17:18 cubox kernel: [<c0256a48>] (bus_for_each_drv+0x60/0x8c) from [<c0258368>] (device_attach+0x80/0xa4)
Aug 10 15:17:18 cubox kernel: [<c0258368>] (device_attach+0x80/0xa4) from [<c02577a8>] (bus_probe_device+0x88/0xac)
Aug 10 15:17:18 cubox kernel: [<c02577a8>] (bus_probe_device+0x88/0xac) from [<c0257c34>] (deferred_probe_work_func+0x6c/0x9c)
Aug 10 15:17:18 cubox kernel: [<c0257c34>] (deferred_probe_work_func+0x6c/0x9c) from [<c0060a74>] (process_one_work+0x190/0x3f4)
Aug 10 15:17:18 cubox kernel: [<c0060a74>] (process_one_work+0x190/0x3f4) from [<c0062544>] (worker_thread+0xf4/0x318)
Aug 10 15:17:18 cubox kernel: [<c0062544>] (worker_thread+0xf4/0x318) from [<c006800c>] (kthread+0xa8/0xb4)
Aug 10 15:17:18 cubox kernel: [<c006800c>] (kthread+0xa8/0xb4) from [<c000e4a8>] (ret_from_fork+0x14/0x2c)

I also get a load of these:

Aug 10 16:09:27 cubox kernel: S!PDIF1: ASoC: no backend DAIs enabled for S/PDIF1

from time to time as there's no way to tell ASoC in a DPCM confirmation
that although the CPU DAI has capture capability, the capture side is
not connected to any codec.

And here's the oops:

Aug 10 22:06:17 cubox kernel: Unable to handle kernel NULL pointer dereference at virtual address 00000008
Aug 10 22:06:17 cubox kernel: pgd = d2450000
Aug 10 22:06:17 cubox kernel: [00000008] *pgd=12285831, *pte=00000000, *ppte=00000000
Aug 10 22:06:17 cubox kernel: Internal error: Oops: 17 [#1] PREEMPT ARM
Aug 10 22:06:17 cubox kernel: Modules linked in: fuse bnep rfcomm bluetooth ext2 ext3 jbd snd_soc_spdif_tx m25p80 orion_wdt mtd snd_soc_kirkwood snd_soc_kirkwood_spdif
Aug 10 22:06:17 cubox kernel: CPU: 0 PID: 2514 Comm: vlc Not tainted 3.10.0+ #652
Aug 10 22:06:17 cubox kernel: task: d8102800 ti: d38fa000 task.ti: d38fa000
Aug 10 22:06:17 cubox kernel: PC is at snd_pcm_info+0xc8/0xd8
Aug 10 22:06:17 cubox kernel: LR is at 0x30232065
Aug 10 22:06:17 cubox kernel: pc : [<c030f724>]    lr : [<30232065>]    psr: a00f0013
Aug 10 22:06:17 cubox kernel: sp : d38fbea8  ip : d8c2ead0  fp : c05de6d8
Aug 10 22:06:17 cubox kernel: r10: c05de7d0  r9 : fffffdfd  r8 : 00000000
Aug 10 22:06:17 cubox kernel: r7 : d8c268a8  r6 : d8c26800  r5 : d8c26c00  r4 : d8c2ea00
Aug 10 22:06:17 cubox kernel: r3 : 00000000  r2 : d8c2ea00  r1 : 00000001  r0 : d8c26c00
Aug 10 22:06:17 cubox kernel: Flags: NzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
Aug 10 22:06:17 cubox kernel: Control: 10c5387d  Table: 12450019  DAC: 00000015
Aug 10 22:06:17 cubox kernel: Process vlc (pid: 2514, stack limit = 0xd38fa248)
Aug 10 22:06:17 cubox kernel: Stack: (0xd38fbea8 to 0xd38fc000)
Aug 10 22:06:17 cubox kernel: bea0:                   c0af7144 d8c2ea00 d8c26c00 ab5032b8 00000001 c030f768
Aug 10 22:06:17 cubox kernel: bec0: 00000000 d8c20000 ab5032b8 c030a67c 0000001b d116b840 d8380330 c1205531
Aug 10 22:06:17 cubox kernel: bee0: 0000001b d116b840 d8263fc0 d8c20000 ab5032b8 c03056b0 00000001 c05e6e80
Aug 10 22:06:17 cubox kernel: bf00: c05e6e88 c05be828 00020120 00000000 d38fa000 600f0013 00000001 0000001b
Aug 10 22:06:17 cubox kernel: bf20: d38fa000 00020000 ab5032b8 c0088fec 00000001 00000000 d38fa000 00000000
Aug 10 22:06:17 cubox kernel: bf40: 600f0013 ca17c380 0000001b ab5032b8 d8380330 0000001b d38fa000 00020000
Aug 10 22:06:17 cubox kernel: bf60: ab5032b8 c00e50bc c00edecc 00020000 ab5032b8 00000001 ca17c380 ab5032b8
Aug 10 22:06:17 cubox kernel: bf80: c1205531 c00e5394 ab50366c 00000001 00000000 000120b0 ab50366c 00000036
Aug 10 22:06:17 cubox kernel: bfa0: c000e5a8 c000e3e0 00000000 000120b0 0000001b c1205531 ab5032b8 a91a3e10
Aug 10 22:06:17 cubox kernel: bfc0: 00000000 000120b0 ab50366c 00000036 ab503454 00000001 00000000 ab5032b8
Aug 10 22:06:17 cubox kernel: [<c030f724>] (snd_pcm_info+0xc8/0xd8) from [<c030f768>] (snd_pcm_info_user+0x34/0x9c)
Aug 10 22:06:17 cubox kernel: [<c030f768>] (snd_pcm_info_user+0x34/0x9c) from [<c030a67c>] (snd_pcm_control_ioctl+0x274/0x280)
Aug 10 22:06:17 cubox kernel: [<c030a67c>] (snd_pcm_control_ioctl+0x274/0x280) from [<c03056b0>] (snd_ctl_ioctl+0xc0/0x55c)
Aug 10 22:06:17 cubox kernel: [<c03056b0>] (snd_ctl_ioctl+0xc0/0x55c) from [<c00e50bc>] (do_vfs_ioctl+0x80/0x31c)
Aug 10 22:06:17 cubox kernel: [<c00e50bc>] (do_vfs_ioctl+0x80/0x31c) from [<c00e5394>] (SyS_ioctl+0x3c/0x60)
Aug 10 22:06:17 cubox kernel: [<c00e5394>] (SyS_ioctl+0x3c/0x60) from [<c000e3e0>] (ret_fast_syscall+0x0/0x48)
Aug 10 22:06:17 cubox kernel: Code: e1a00005 e59530dc e3a01001 e1a02004 (e5933008)

This is caused because substream->ops is NULL.  Why that's the case,
I don't know, but I believe the PCM which is trying to be operated on
is the one registered against the backend (by snd_pcm_new_internal).

This is why I'm soo frustrated with Mark: Mark just churns the same
old useless statements out without _listening_ to anything I've said
or providing anything useful to help with the problems I find.