On Sat, Aug 10, 2013 at 05:11:23PM +0100, Russell King - ARM Linux wrote:

On Tue, Aug 06, 2013 at 02:32:06PM +0100, Mark Brown wrote:

quoted

On Tue, Aug 06, 2013 at 12:30:15AM +0100, Russell King - ARM Linux wrote:

quoted

I put it to you that DPCM in mainline is incomplete and nonfunctional
as it currently stands.  Moreover, it requires either those who know
that code to continue to develop it, or someone else who understands
the direction that this code is supposed to go picks up to complete it.

I'd be most distressed if it were far off working; it's close enough to
the out of tree code I've worked with and I know there were drivers in
progress when it was submitted.  We've certainly had at least one bug
fix from the out of tree users, I'd be surprised if we had anything more
substantial than bitrot in the current code.

Right, so, I've looked at this again today, and I've sort-of got it
working.

I'm not so sure about that:

Unable to handle kernel NULL pointer dereference at virtual address 00000008
pgd = d2450000
[00000008] *pgd=12285831, *pte=00000000, *ppte=00000000
Internal error: Oops: 17 [#1] PREEMPT ARM
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
CPU: 0 PID: 2514 Comm: vlc Not tainted 3.10.0+ #652
task: d8102800 ti: d38fa000 task.ti: d38fa000
PC is at snd_pcm_info+0xc8/0xd8
LR is at 0x30232065
pc : [<c030f724>]    lr : [<30232065>]    psr: a00f0013
sp : d38fbea8  ip : d8c2ead0  fp : c05de6d8
r10: c05de7d0  r9 : fffffdfd  r8 : 00000000
r7 : d8c268a8  r6 : d8c26800  r5 : d8c26c00  r4 : d8c2ea00
r3 : 00000000  r2 : d8c2ea00  r1 : 00000001  r0 : d8c26c00
Flags: NzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
Control: 10c5387d  Table: 12450019  DAC: 00000015
Process vlc (pid: 2514, stack limit = 0xd38fa248)
Stack: (0xd38fbea8 to 0xd38fc000)
bea0:                   c0af7144 d8c2ea00 d8c26c00 ab5032b8 00000001 c030f768
bec0: 00000000 d8c20000 ab5032b8 c030a67c 0000001b d116b840 d8380330 c1205531
bee0: 0000001b d116b840 d8263fc0 d8c20000 ab5032b8 c03056b0 00000001 c05e6e80
bf00: c05e6e88 c05be828 00020120 00000000 d38fa000 600f0013 00000001 0000001b
bf20: d38fa000 00020000 ab5032b8 c0088fec 00000001 00000000 d38fa000 00000000
bf40: 600f0013 ca17c380 0000001b ab5032b8 d8380330 0000001b d38fa000 00020000
bf60: ab5032b8 c00e50bc c00edecc 00020000 ab5032b8 00000001 ca17c380 ab5032b8
bf80: c1205531 c00e5394 ab50366c 00000001 00000000 000120b0 ab50366c 00000036
bfa0: c000e5a8 c000e3e0 00000000 000120b0 0000001b c1205531 ab5032b8 a91a3e10
bfc0: 00000000 000120b0 ab50366c 00000036 ab503454 00000001 00000000 ab5032b8
bfe0: b69a00f4 ab5032a4 b6933109 b6e0d07c a00f0010 0000001b aaaaaaaa aaaaaaaa
[<c030f724>] (snd_pcm_info+0xc8/0xd8) from [<c030f768>] (snd_pcm_info_user+0x34/0x9c)
[<c030f768>] (snd_pcm_info_user+0x34/0x9c) from [<c030a67c>] (snd_pcm_control_ioctl+0x274/0x280)
[<c030a67c>] (snd_pcm_control_ioctl+0x274/0x280) from [<c03056b0>] (snd_ctl_ioctl+0xc0/0x55c)
[<c03056b0>] (snd_ctl_ioctl+0xc0/0x55c) from [<c00e50bc>] (do_vfs_ioctl+0x80/0x31c)
[<c00e50bc>] (do_vfs_ioctl+0x80/0x31c) from [<c00e5394>] (SyS_ioctl+0x3c/0x60)
[<c00e5394>] (SyS_ioctl+0x3c/0x60) from [<c000e3e0>] (ret_fast_syscall+0x0/0x48)
Code: e1a00005 e59530dc e3a01001 e1a02004 (e5933008)

That is caused by:

        /* AB: FIXME!!! This is definitely nonsense */
        if (runtime) {
                info->sync = runtime->sync;
                substream->ops->ioctl(substream, SNDRV_PCM_IOCTL1_INFO, info);
        }

where substream->ops is NULL.

So, we're back to square one and DPCM not being correctly functional.