15 December 2008, 17:53

Kernel Log: What's coming in 2.6.28 - Part 6: Changes to the audio drivers

As the development of Linux kernel 2.6.28 is approaching completion, this kernel log will mention a few changes that haven't made it into the "What's coming in 2.6.28" series so far. This includes the changes to the audio drivers – these drivers were already raised to the status of the Alsa development branch early on in the current development cycle, but were then updated several times. While the audio drivers of Linux 2.6.28 will roughly correspond to the Alsa driver version 1.0.18, they already include several minor improvements and corrections not yet contained in the latest version of the official Alsa driver archive.

The changes incorporated into the main development branch include a new userspace interface used by applications to detect which audio input or output devices are connected to which audio jacks (Jack Sensing). Also new is the snd-usb-us122l driver for the Tascam US-122L USB Audio/MIDI Interface; the snd-virtuoso driver can now also handle the Asus Xonar HDAV1.3 and the Xonar HDAV1.3 Deluxe.

There is also added or improved support for the AC97 and HD audio codecs by various vendors – for example for AD1882A and AD1980 by Analog Devices, ALC662 and 663 by Realtek, as well as VT1708S and VT1702 by VIA. There are also many new drivers for the ASoC (ALSA System on Chip) framework used particularly in embedded systems – for example drivers for the WM8903, WM8580, WM8900 and WM8971 codecs by Wolfson Microelectronics.

As in almost every new kernel version, the developers extended the whitelists for the automatic application of specific hardware workarounds, which allows drivers to automatically apply the special treatment for audio codecs required with many PCs, notebooks and mainboards for more types of hardware than before – in 2.6.28, this includes the Dell Studio 15, the HP Compaq 6730s and the Medion MD96630. On the other hand, the kernel developers removed the hal2 OSS driver. OSS emulation in the Alsa soundcore model is now optional, which allows alternative implementations – like the as yet experimental OSS proxy, which is based on the equally experimental CUSE (character devices in user space) (see also the article on LWN.net). Apart from Jaroslav Kysela, who has been working for Red Hat for several months now, the kernel sources now also officially list Alsa developer and Suse employee Takashi Iwai as an audio driver maintainer.

Further commits in connection with the audio drivers:

Further background and information about developments in the Linux kernel and its environment can also be found in previous issues of the kernel log at heise open:

Older Kernel logs can be found in the archives or by using the search function at heise open. (thl/c't)

(djwm)

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