kernel/git/stable/linux.git/sound/firewire, branch linux-4.8.y

ALSA: fireworks: accessing to user space outside spinlock

2016-08-31T14:17:15+00:00

In hwdep interface of fireworks driver, accessing to user space is in a critical section with disabled local interrupt. Depending on architecture, accessing to user space can cause page fault exception. Then local processor stores machine status and handles the synchronous event. A handler corresponding to the event can call task scheduler to wait for preparing pages. In a case of usage of single core processor, the state to disable local interrupt is worse because it don't handle usual interrupts from hardware. This commit fixes this bug, performing the accessing outside spinlock. This commit also gives up counting the number of queued response messages to simplify ring-buffer management. Reported-by: Vaishali Thakkar Cc: stable@vger.kernel.org Fixes: 555e8a8f7f14('ALSA: fireworks: Add command/response functionality into hwdep interface') Signed-off-by: Takashi Sakamoto Signed-off-by: Takashi Iwai

ALSA: firewire-tascam: accessing to user space outside spinlock

2016-08-31T12:24:37+00:00

In hwdep interface of firewire-tascam driver, accessing to user space is in a critical section with disabled local interrupt. Depending on architecture, accessing to user space can cause page fault exception. Then local processor stores machine status and handle the synchronous event. A handler corresponding to the event can call task scheduler to wait for preparing pages. In a case of usage of single core processor, the state to disable local interrupt is worse because it doesn't handle usual interrupts from hardware. This commit fixes this bug, by performing the accessing outside spinlock. Reported-by: Vaishali Thakkar Cc: stable@vger.kernel.org Fixes: e5e0c3dd257b('ALSA: firewire-tascam: add hwdep interface') Signed-off-by: Takashi Sakamoto Signed-off-by: Takashi Iwai

ALSA: firewire-lib: change a member of event structure to suppress sparse wanings to bool type

2016-05-18T14:32:09+00:00

Commit a9c4284bf5a9 ("ALSA: firewire-lib: add context information to tracepoints") adds new members to tracepoint events of this module, to represent context information. One of the members is bool type and this causes sparse warnings. 16:1: warning: expression using sizeof bool 60:1: warning: expression using sizeof bool 16:1: warning: odd constant _Bool cast (ffffffffffffffff becomes 1) 60:1: warning: odd constant _Bool cast (ffffffffffffffff becomes 1) This commit suppresses the warnings, by changing type of the member to 'unsigned int'. Additionally, this commit applies '!!' idiom to get 0/1 from 'in_interrupt()'. Fixes: a9c4284bf5a9 ("ALSA: firewire-lib: add context information to tracepoints") Signed-off-by: Takashi Sakamoto Signed-off-by: Takashi Iwai

ALSA: firewire-lib: drop skip argument from helper functions to queue a packet

2016-05-11T18:36:28+00:00

On most of audio and music units on IEEE 1394 bus which ALSA firewire stack supports (or plans to support), CIP with two quadlets header is used. Thus, there's no cases to queue packets with blank payload. If such packets are going to be queued, it means that they're for skips of the cycle. This commit simplifies helper functions to queue a packet. Signed-off-by: Takashi Sakamoto Acked-by: Clemens Ladisch Signed-off-by: Takashi Iwai

ALSA: firewire-lib: add context information to tracepoints

2016-05-11T18:36:00+00:00

In current implementation, packet processing is done in both of software IRQ contexts of IR/IT contexts and process contexts. This is usual interrupt handling of IR/IT context for 1394 OHCI. (in hardware IRQ context) irq_handler() (drivers/firewire/ohci.c) ->tasklet_schedule() (in software IRQ context) handle_it_packet() or handle_ir_packet_per_buffer() (drivers/firewire/ohci.c) ->flush_iso_completions() ->struct fw_iso_context.callback.sc() = out_stream_callback() or in_stream_callback() However, we have another chance for packet processing. It's done in PCM frame handling via ALSA PCM interfaces. (in process context) ioctl(i.e. SNDRV_PCM_IOCTL_HWSYNC) ->snd_pcm_hwsync() (sound/core/pcm_native.c) ->snd_pcm_update_hw_ptr() (sound/core/pcm_lib.c) ->snd_pcm_update_hw_ptr0() ->struct snd_pcm_ops.pointer() = amdtp_stream_pcm_pointer() ->fw_iso_context_flush_completions() (drivers/firewire/core-iso.c) ->struct fw_card_driver.flush_iso_completions() = ohci_flush_iso_completions() (drivers/firewire/ohci.c) ->flush_iso_completions() ->struct fw_iso_context.callback.sc() = out_stream_callback() or in_stream_callback() This design is for a better granularity of PCM pointer. When ioctl(2) is executed with some commands for ALSA PCM interface, queued packets are handled at first. Then, the latest number of handled PCM frames is reported. The number can represent PCM frames transferred in most near isochronous cycle. Current tracepoints include no information to distinguish running contexts. When tracing the interval of software IRQ context, this is not good. This commit adds more information for current context. Additionally, the index of packet processed in one context is added in a case that packet processing is executed in continuous context of the same kind, As a result, the output includes 11 fields with additional two fields to commit 0c95c1d6197f ("ALSA: firewire-lib: add tracepoints to dump a part of isochronous packet data"): 17131.9186: out_packet: 07 7494 ffc0 ffc1 00 000700c0 9001a496 058 45 1 13 17131.9186: out_packet: 07 7495 ffc0 ffc1 00 000700c8 9001ba00 058 46 1 14 17131.9186: out_packet: 07 7496 ffc0 ffc1 00 000700d0 9001ffff 002 47 1 15 17131.9189: out_packet: 07 7497 ffc0 ffc1 00 000700d0 9001d36a 058 00 0 00 17131.9189: out_packet: 07 7498 ffc0 ffc1 00 000700d8 9001e8d4 058 01 0 01 17131.9189: out_packet: 07 7499 ffc0 ffc1 00 000700e0 9001023e 058 02 0 00 17131.9206: in_packet: 07 7447 ffc1 ffc0 01 3f070072 9001783d 058 32 1 00 17131.9206: in_packet: 07 7448 ffc1 ffc0 01 3f070072 90ffffff 002 33 1 01 17131.9206: in_packet: 07 7449 ffc1 ffc0 01 3f07007a 900191a8 058 34 1 02 (Here, some common fields are omitted so that a line is within 80 characters.) The legend is: - The second of cycle scheduled for the packet - The count of cycle scheduled for the packet - The ID of node as source (hex) - The ID of node as destination (hex) - The value of isochronous channel - The first quadlet of CIP header (hex) - The second quadlet of CIP header (hex) - The number of included quadlets - The index of packet in a buffer maintained by this module - 0 in process context, 1 in IRQ context - The index of packet processed in the context Signed-off-by: Takashi Sakamoto Signed-off-by: Takashi Iwai

ALSA: firewire-lib: permit to flush queued packets only in process context for better PCM period granularity

2016-05-11T18:34:53+00:00

These three commits were merged to improve PCM pointer granularity. commit 76fb87894828 ("ALSA: firewire-lib: taskletize the snd_pcm_period_elapsed() call") commit e9148dddc3c7 ("ALSA: firewire-lib: flush completed packets when reading PCM position") commit 92b862c7d685 ("ALSA: firewire-lib: optimize packet flushing") The point of them is to handle queued packets not only in software IRQ context of IR/IT contexts, but also in process context. As a result of handling packets, period tasklet is scheduled when acrossing PCM period boundary. This is to prevent recursive call of 'struct snd_pcm_ops.pointer()' in the same context. When the pointer callback is executed in the process context, it's better to avoid the second callback in the software IRQ context. The software IRQ context runs immediately after scheduled in the process context because few packets are queued yet. For the aim, 'pointer_flush' is used, however it causes a race condition between the process context and software IRQ context of IR/IT contexts. Practically, this race is not so critical because it influences process context to skip flushing queued packet and to get worse granularity of PCM pointer. The race condition is quite rare but it should be improved for stable service. The similar effect can be achieved by using 'in_interrupt()' macro. This commit obsoletes 'pointer_flush' with it. Acked-by: Clemens Ladisch Signed-off-by: Takashi Sakamoto Signed-off-by: Takashi Iwai

ALSA: firewire-lib: enable the same feature as CIP_SKIP_INIT_DBC_CHECK flag

2016-05-10T15:04:01+00:00

In former commit, drivers in ALSA firewire stack always starts IT context before IR context. If IR context starts after packets are transmitted by peer unit, packet discontinuity may be detected because the context starts in the middle of packet streaming. This situation is rare because IT context usually starts immediately. However, it's better to solve this issue. This is suppressed with CIP_SKIP_INIT_DBC_CHECK flag. This commit enables the same feature as CIP_SKIP_INIT_DBC_CHECK. Signed-off-by: Takashi Sakamoto Signed-off-by: Takashi Iwai

ALSA: firewire-lib: code cleanup for outgoing packet handling

2016-05-10T15:04:01+00:00

In previous commit, this module has no need to reuse parameters of incoming packets for outgoing packets anymore. This commit arranges some needless codes for outgoing packet processing. Signed-off-by: Takashi Sakamoto Signed-off-by: Takashi Iwai

ALSA: firewire-lib: code cleanup for incoming packet handling

2016-05-10T15:04:00+00:00

In previous commit, this module has no need to reuse parameters of incoming packets for outgoing packets anymore. This commit arranges some needless codes for incoming packet processing. Signed-off-by: Takashi Sakamoto Signed-off-by: Takashi Iwai

ALSA: firewire-lib: handle IT/IR contexts in each software interrupt context

2016-05-10T15:03:59+00:00

In clause 6.3 of IEC 61883-6:2000, there's an explanation about processing of presentation timestamp. In the clause, we can see "If a function block receives a CIP, processes it and subsequently re-transmits it, then the SYT of the outgoing CIP shall be the sum of the incoming SYT and the processing delay." ALSA firewire stack has an implementation to partly satisfy this specification. Developers assumed the stack to perform as an Audio function block[1]. Following to the assumption, current implementation of ALSA firewire stack use one software interrupt context to handle both of in/out packets. In most case, this is processed in 1394 OHCI IR context independently of the opposite context. Thus, this implementation uses longer CPU time in the software interrupt context. This is not better for whole system. Against the assumption, I confirmed that each ASIC for IEC 61883-1/6 doesn't necessarily expect it to the stack. Thus, current implementation of ALSA firewire stack includes over-engineering. This commit purges the implementation. As a result, packets of one direction are handled in one software interrupt context and spends minimum CPU time. [1] [alsa-devel] [PATCH 0/8] [RFC] new driver for Echo Audio's Fireworks based devices http://mailman.alsa-project.org/pipermail/alsa-devel/2013-June/062660.html Signed-off-by: Takashi Sakamoto Signed-off-by: Takashi Iwai