14 May 2010, 09:10

Kernel Log: Coming in 2.6.34 (Part 5) - Drivers

by Thorsten Leemhuis

Hundreds of new and improved drivers significantly improve hardware support in the 2.6.34 kernel.

In his release email for Linux 2.6.34-rc7 last weekend, Linus Torvalds indicated that version 2.6.34 of the Linux kernel will be released soon. The following article describes the advancements in terms of drivers and their infrastructure and concludes our "Coming in 2.6.34" mini series about the most important new features of Linux 2.6.34. The most important changes in the areas of network support, file systems, storage subsystem, graphics hardware and architecture as well as virtualisation were discussed in parts one, two, three and four of the series, along with the drivers associated with these kernel areas.

Audio and video

The main Git-Pull request by audio subsystem maintainer Takashi Iwai lists the most important new features of the kernel's audio drivers, which are now on the same level as version 1.0.22.1 of the ALSA drivers.

For instance, the sound drivers now support 8-channel audio output via HDMI for GeForce graphics cards with GT21x GPUs as well as for NVIDIA's series MCP89 motherboard chip-sets. The kernel now offers the first components of the driver code required to support version 2.0 of the USB audio specification. New too is support for the Xonar DS sound card by ASUS and a driver for the Edirol UA-101 audio/MIDI interface.

The V4L/DVB subsystem, which handles TV hardware, was supplemented with the tlg2300 drivers for the Telegent Tlg2300 chip as well as the nGene driver for the identically named chip by Micronas (1, 2). The developers have also added the cpia1 Gspca subdriver for CpiA webcam chips; this chip was previously handled by cpia, a driver which has now been marked as deprecated; various other webcam drivers for which the kernel offers different Gspca-based drivers have also been tagged this way.

Input devices and notebooks

The input subsystem has been given drivers for touch screen interfaces by various vendors. Also new are drivers for Apple's Magic Mouse and Logitech's G940 Flight System.

Vendor-specific notebook drivers will now be maintained by Matthew Garrett as part of the "x86 platform drivers" subsystem. This subsystem now includes a simple eeepc-wmi driver which previously only controlled display brightness and works with recent ASUS Eee PCs that use WMI for the function keys. Numerous detail improvements were made to the drivers for notebooks by ASUS, Dell, Lenovo/IBM, MSI and Toshiba; these drivers were previously handled by the ACPI maintainer.

USB and staging

The xHCI driver for USB 3.0 controller chips, which was previously called xhci, has been renamed xhci_hcd to match the naming scheme used for other USB host controller drivers. A modification implemented by Torvalds himself now causes the USB storage driver to wait just one second instead of the previous five before it addresses a newly connected USB memory device. Various distributions reduced or completely disabled the delay quite some time ago. Torvalds says it is unclear whether devices that require such a delay are still in use; it could be that this issue is purely historical. The modification is designed to help clarify this question; "Let's see if anybody screams" said Torvalds.

The crystalhd driver for the Broadcom Crystal HD video accelerator has been added to the staging branch. Major improvements – including one which enhances performance – were made to the udlfb DisplayLink driver, which is also located in the staging area (1, 2, 3). Various changes to the rtl8192e driver are to considerably reduce the power consumption of the identically named Realtek chips during operation. The kernel developers have removed the altpciechdma, b3dfg mimio and p9auth staging drivers because nobody showed any interest in developing them further. A new addition is the dt3155 driver for DT3155 Digitisers.

In brief

Drivers and extensions for Intel's motherboard chip-sets so far only referred to as Cougar Point and expected to be released early next year have been added to various subsystems.
The AHCI driver now offers FIS-based switching – a technology for addressing multiple hard disks via one SATA connection which is used by some external disk housings with SATA port multipliers.
Performance improvements to the CFQ I/O scheduler are among the major changes to the block layer, highlighted by maintainer Jens Axboe in his main Git-Pull request.

Minor gems

Many further minor, but by no means insignificant, changes can be found in the list below, which contains the commit headers referring to the respective change. Like many of the references in the text above, the links point to the relevant commit in the web front end of the Git branch for the kernel sources maintained by Linus Torvalds at kernel.org. The commit comments and the patches themselves provide extensive further information on the respective changes.

Audio

FireWire

HID, Input

Hwmonitor, I2C, Watchdog

Notebook and system specific drivers

Staging

Storage

Block-Layer, DM and MD

Libata

MFD, MMC, MTD

SCSI

Other storage:

USB

V4L/DVB

Other drivers

Latecomers

The previous five parts of the Kernel Log mini series have already given a detailed overview of the many changes in of the Linux kernel. All of the major enhancements have already been mentioned there, as they entered the main development branch during the first phase of the development cycle. But some small, usually not quite as important changes that fall in the "minor gems" section, were late entries to the kernel – for completeness, we have included these changes in the following list.

The ipheth driver that allows for tethering with an iPhone device is a late inclusion, as are:

Network

For other articles on 2.6.34 and links to the rest of the "Coming in 2.6.34" series, see The H's Kernel Log - 2.6.34 Tracking page. New editions of Kernel Logs are also mentioned on Identi.ca and Twitter via "@kernellog2". The Kernel Log author also posts updates about various topics on Identi.ca and Twitter via "@kernellogauthor".

(crve)

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