From a7611e84bd06c70c8b0cd88cd1e474c3c42fee3e Mon Sep 17 00:00:00 2001 From: Clemens Ladisch Date: Mon, 12 Mar 2012 21:46:55 +0100 Subject: firewire: cdev: fix IR multichannel event documentation State more precisely when fw_cdev_event_iso_interrupt_mc is sent. While the comment tried to reflect an amibuity in the OHCI specification, there is only one method that is useful in practice, and this also matches all the hardware implementations I've tested. Signed-off-by: Clemens Ladisch Signed-off-by: Stefan Richter --- include/linux/firewire-cdev.h | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'include/linux/firewire-cdev.h') diff --git a/include/linux/firewire-cdev.h b/include/linux/firewire-cdev.h index 357dbfc2829e..cc1b570a2eb3 100644 --- a/include/linux/firewire-cdev.h +++ b/include/linux/firewire-cdev.h @@ -267,9 +267,8 @@ struct fw_cdev_event_iso_interrupt { * * This event is sent in multichannel contexts (context type * %FW_CDEV_ISO_CONTEXT_RECEIVE_MULTICHANNEL) for &fw_cdev_iso_packet buffer - * chunks that have the %FW_CDEV_ISO_INTERRUPT bit set. Whether this happens - * when a packet is completed and/or when a buffer chunk is completed depends - * on the hardware implementation. + * chunks that have been completely filled and that have the + * %FW_CDEV_ISO_INTERRUPT bit set. * * The buffer is continuously filled with the following data, per packet: * - the 1394 iso packet header as described at &fw_cdev_event_iso_interrupt, -- cgit v1.2.3 From 18d627113b830cda80792e96b28341bcd41cf40c Mon Sep 17 00:00:00 2001 From: Clemens Ladisch Date: Sun, 18 Mar 2012 19:05:29 +0100 Subject: firewire: prevent dropping of completed iso packet header data The buffer for the header data of completed iso packets has a fixed size, so it is possible to configure a stream with a big interval between interrupt packets or with big headers so that this buffer would overflow. Previously, ohci.c would drop any data that would not fit, but this could make unsuspecting applications believe that fewer than the actual number of packets have completed. Instead of dropping data, add calls to flush_iso_completion() so that there are as many events as needed to report all of the data. Signed-off-by: Clemens Ladisch Signed-off-by: Stefan Richter --- include/linux/firewire-cdev.h | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'include/linux/firewire-cdev.h') diff --git a/include/linux/firewire-cdev.h b/include/linux/firewire-cdev.h index cc1b570a2eb3..b9bd349c6930 100644 --- a/include/linux/firewire-cdev.h +++ b/include/linux/firewire-cdev.h @@ -207,12 +207,15 @@ struct fw_cdev_event_request2 { * @closure: See &fw_cdev_event_common; * set by %FW_CDEV_CREATE_ISO_CONTEXT ioctl * @type: See &fw_cdev_event_common; always %FW_CDEV_EVENT_ISO_INTERRUPT - * @cycle: Cycle counter of the interrupt packet + * @cycle: Cycle counter of the last completed packet * @header_length: Total length of following headers, in bytes * @header: Stripped headers, if any * * This event is sent when the controller has completed an &fw_cdev_iso_packet - * with the %FW_CDEV_ISO_INTERRUPT bit set. + * with the %FW_CDEV_ISO_INTERRUPT bit set, or when there have been so many + * completed packets without the interrupt bit set that the kernel's internal + * buffer for @header is about to overflow. (In the latter case, kernels with + * ABI version < 5 drop header data up to the next interrupt packet.) * * Isochronous transmit events (context type %FW_CDEV_ISO_CONTEXT_TRANSMIT): * @@ -440,6 +443,8 @@ union fw_cdev_event { * - added %FW_CDEV_EVENT_ISO_INTERRUPT_MULTICHANNEL, * %FW_CDEV_ISO_CONTEXT_RECEIVE_MULTICHANNEL, and * %FW_CDEV_IOC_SET_ISO_CHANNELS + * 5 (3.4) - send %FW_CDEV_EVENT_ISO_INTERRUPT events when needed to + * avoid dropping data */ /** -- cgit v1.2.3 From d1bbd20972936b9b178fda3eb1ec417cb27fdc01 Mon Sep 17 00:00:00 2001 From: Clemens Ladisch Date: Sun, 18 Mar 2012 19:06:39 +0100 Subject: firewire: allow explicit flushing of iso packet completions Extend the kernel and userspace APIs to allow reporting all currently completed isochronous packets, even if the next interrupt packet has not yet been reached. This is required to determine the status of the packets at the end of a paused or stopped stream, and useful for more precise synchronization of audio streams. Signed-off-by: Clemens Ladisch Signed-off-by: Stefan Richter --- include/linux/firewire-cdev.h | 35 ++++++++++++++++++++++++++++++----- 1 file changed, 30 insertions(+), 5 deletions(-) (limited to 'include/linux/firewire-cdev.h') diff --git a/include/linux/firewire-cdev.h b/include/linux/firewire-cdev.h index b9bd349c6930..d50036953497 100644 --- a/include/linux/firewire-cdev.h +++ b/include/linux/firewire-cdev.h @@ -212,10 +212,11 @@ struct fw_cdev_event_request2 { * @header: Stripped headers, if any * * This event is sent when the controller has completed an &fw_cdev_iso_packet - * with the %FW_CDEV_ISO_INTERRUPT bit set, or when there have been so many - * completed packets without the interrupt bit set that the kernel's internal - * buffer for @header is about to overflow. (In the latter case, kernels with - * ABI version < 5 drop header data up to the next interrupt packet.) + * with the %FW_CDEV_ISO_INTERRUPT bit set, when explicitly requested with + * %FW_CDEV_IOC_FLUSH_ISO, or when there have been so many completed packets + * without the interrupt bit set that the kernel's internal buffer for @header + * is about to overflow. (In the last case, kernels with ABI version < 5 drop + * header data up to the next interrupt packet.) * * Isochronous transmit events (context type %FW_CDEV_ISO_CONTEXT_TRANSMIT): * @@ -271,7 +272,8 @@ struct fw_cdev_event_iso_interrupt { * This event is sent in multichannel contexts (context type * %FW_CDEV_ISO_CONTEXT_RECEIVE_MULTICHANNEL) for &fw_cdev_iso_packet buffer * chunks that have been completely filled and that have the - * %FW_CDEV_ISO_INTERRUPT bit set. + * %FW_CDEV_ISO_INTERRUPT bit set, or when explicitly requested with + * %FW_CDEV_IOC_FLUSH_ISO. * * The buffer is continuously filled with the following data, per packet: * - the 1394 iso packet header as described at &fw_cdev_event_iso_interrupt, @@ -421,6 +423,9 @@ union fw_cdev_event { #define FW_CDEV_IOC_RECEIVE_PHY_PACKETS _IOW('#', 0x16, struct fw_cdev_receive_phy_packets) #define FW_CDEV_IOC_SET_ISO_CHANNELS _IOW('#', 0x17, struct fw_cdev_set_iso_channels) +/* available since kernel version 3.4 */ +#define FW_CDEV_IOC_FLUSH_ISO _IOW('#', 0x18, struct fw_cdev_flush_iso) + /* * ABI version history * 1 (2.6.22) - initial version @@ -445,6 +450,7 @@ union fw_cdev_event { * %FW_CDEV_IOC_SET_ISO_CHANNELS * 5 (3.4) - send %FW_CDEV_EVENT_ISO_INTERRUPT events when needed to * avoid dropping data + * - added %FW_CDEV_IOC_FLUSH_ISO */ /** @@ -854,6 +860,25 @@ struct fw_cdev_stop_iso { __u32 handle; }; +/** + * struct fw_cdev_flush_iso - flush completed iso packets + * @handle: handle of isochronous context to flush + * + * For %FW_CDEV_ISO_CONTEXT_TRANSMIT or %FW_CDEV_ISO_CONTEXT_RECEIVE contexts, + * report any completed packets. + * + * For %FW_CDEV_ISO_CONTEXT_RECEIVE_MULTICHANNEL contexts, report the current + * offset in the receive buffer, if it has changed; this is typically in the + * middle of some buffer chunk. + * + * Any %FW_CDEV_EVENT_ISO_INTERRUPT or %FW_CDEV_EVENT_ISO_INTERRUPT_MULTICHANNEL + * events generated by this ioctl are sent synchronously, i.e., are available + * for reading from the file descriptor when this ioctl returns. + */ +struct fw_cdev_flush_iso { + __u32 handle; +}; + /** * struct fw_cdev_get_cycle_timer - read cycle timer register * @local_time: system time, in microseconds since the Epoch -- cgit v1.2.3