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This commit adds PCM functionality to transmit/receive PCM frames on isochronous packet streaming. This commit enables userspace applications to start/stop packet streaming via ALSA PCM interface. Sampling rate requested by applications is used as sampling transmission frequency of IEC 61883-1/6packet streaming. As I described in followed commits, units in this series manages sampling clock frequency independently of sampling transmission frequency, and they supports resampling between their packet streaming/data block processing layer and sampling data processing layer. This commit take this driver to utilize these features for usability. When internal clock is selected as source signal of sampling clock, this driver allows user space applications to start PCM substreams at any rate which packet streaming engine supports as sampling transmission frequency. In this case, this driver expects units to perform resampling PCM frames for rx/tx packets when sampling clock frequency and sampling transmission frequency are mismatched. This is for daily use cases. When any external clock is selected as the source signal, this driver gets configured sampling rate from units, then restricts available sampling rate to the rate for PCM applications. This is for studio use cases. Models in this series supports 64.0/128.0 kHz of sampling rate, however these frequencies are not supported by IEC 61883-6 as sampling transmission frequency. Therefore, packet streaming engine of ALSA firewire stack can't handle them. When units are configured to use any external clock as source signal of sampling clock and one of these unsupported rate is configured as rate of the sampling clock, this driver returns EIO to user space applications. Anyway, this driver doesn't voluntarily configure parameters of sampling clock. It's better for users to work with appropriate user space implementations to configure the parameters in advance of usage. Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp> Signed-off-by: Takashi Iwai <tiwai@suse.de> |
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Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.