Older blog entries for broonie (starting at number 115)

ASoC updates in 3.4

Linux version 3.4 has been released. This was a very active release for ASoC in framework terms, in addition to the usual bug fixes and so on there were a large number of framework enhancements though most are fairly small or are laying the groundwork for more user visible features like dynamic PCM.

  • Support for widgets not associated with a CODEC, an important part of the dynamic PCM framework.
  • A library factoring out the common code shared by dmaengine based DMA drivers contributed by Lars-Peter Clausen. This will save a lot of code and make it much easier to deploy enhancements to dmaengine.
  • Support for binary controls, used for providing runtime configuration of algorithm coefficients.
  • A new DAPM widget type for regulator supplies allowing drivers for devices that can power down unused supplies while active to do without any per-driver code.
  • DAPM widgets for DAIs, initially giving a speed boost for playback startup and shutdown and also the basis for CODEC<->CODEC DAI link support.
  • Support for specifying the number of significant bits on audio interfaces, useful for allowing applications to know how much effort to put into generating data for a larger sample format.
  • Support for a range of new TI reference boards including Panda, configured from platform data so new boards can be added without driver changes.
  • Conversion of the FSI driver used on some SH processors to DMAEngine.
  • New CODEC drivers for Maxim MAX9768 and Wolfson Microelectronics WM2200.

Syndicated 2012-05-22 15:43:43 from Technicalities

ASoC updates in 3.3

Linux 3.3 was released earlier this week. Aside from a few regmap related updates it was an extremely quiet release for the ASoC framework, the next few releases look like they will be much more active:

  • Conversion of a number of CODEC drivers to use regmap directly. This is especially beneficial for drivers for devices which are part of MFDs as they can use a central cache for all operations and means that the process of factoring out the more complex register management code in ASoC can begin.
  • As a result of the move of drivers to regmap the rbtree and LZO cache types have been removed, leaving only the the basic flat cache in ASoC. Drivers which need the more complex cache types should use regmap directly.
  • Lots of cleanups and fixes from Axel Lin.
  • New CODEC drivers for Cirrus CS42L73 and Realtek ALC5632.

Syndicated 2012-03-23 01:26:49 from Technicalities

regulator updates in 3.3

Linux 3.3 was released today. This was the biggest release for the regulator API for quite some time thanks to the contribution of device tree bindings for the API by Rajendra Nayak, the first substantial framework update for a long time, but otherwise was fairly quiet:

  • OpenFirmware bindings for the core and for the fixed regulator driver, contributed by Rajendra Nayak. Device tree bindings for the Freescale MC13892 PMIC were also added.
  • A new regulator_bulk_force_disable() operation contributed by Donggeun Kim.
  • A new driver for the Dialog DA9052 PMIC.

Syndicated 2012-03-19 19:01:19 from Technicalities

regmap updates in 3.3

After the rush of new features in version 3.2 this has been a fairly quiet cycle for the regmap API, the main change being the wider usage by drivers. In terms of development of the subsystem itself this release sees:

  • Introduction of a generic interrupt controller for regmap based devices, this is already used by a few drivers with more coming.
  • Support for 10 bit register 14 bit value devices.
  • Removal of the indexed cache type – devices which would have used it should use rbtree instead. If anything the rbtree cache is expected to be faster for small devices as where registers are grouped together into blocks it will usually be cheaper to search the rbtree.
  • Some improvements to the coverage of the tracepoints..
  • Diagnostics showing the number and size of nodes in an rbtree cache.

Syndicated 2012-03-19 11:41:24 from Technicalities

Yahoo! Groups spam

Yahoo! Groups have for a long time had big problems with allowing people to create obvious spam groups (randomly generated names, no meaningful description and so on) and then add people without any confirmation. This was annoying but at least they have an obvious abuse reporting link in the subscription mails. Sadly rather than improve the situation they appear to have just changed the link to not be a direct link to the reporting form but instead to be a generic help page. The link didn’t change, the content just got even less useful.

I’m strongly tempted to just block all of Yahoo! from the mail systems I control.

Syndicated 2012-02-27 13:39:06 from Technicalities


Earlier today I gave a talk at Android Builders Summit about TinyHAL, a generic audio HAL for Android aimed providing a better basis for system integrators to work from. More details on TinyHAL and slides from the talk can be found over at the Wolfson Open Source web site.

Syndicated 2012-02-14 21:50:19 from Technicalities

regmap updates in 3.2

Version 3.1 of the Linux kernel was the first release to include regmap support and only included a bare minimum of features in order to ease review so version 3.2 has been a pretty big one for regmap development with some pretty major features being built on top of the core code.

  • Support for register caches – Dimitris Papastamos ported his code for rbtree and LZO caches from ASoC over to regmap. This makes it easy for drivers to cache the current values of the device registers, improving performance by eliminating reads when doing read/modify/write cycles and providing functions to restore the register cache when resuming from power down. An indexed cache type was also added but this will be removed in 3.3 as it offers no real advantage over rbtree.
  • Support for a wider range of SPI register transfer formats contributed by Lars-Peter Clausen.
  • Tracepoints supporting both register access logging and monitoring of the time spent on register I/O operations.
  • Register map dumps via debugfs to help provide diagnostic information during development.

Syndicated 2012-01-06 23:59:19 from Technicalities

ASoC updates in 3.2

Linux 3.2 was released yesterday. It’s been a fairly busy release for ASoC in terms of the subsystem, including the first piece of work at moving the register I/O code over to regmap to eliminate the duplication there, but a pretty quiet one on the drivers front.

  • Substantial optimization of the DAPM algorithm, substantially reducing the CPU usage when power states change. This is especially beneficial with larger modern devices.
  • Support for CODEC drivers using the regmap API.
  • Some smaller API updates – support for larger register maps, support for specifying a source when setting a sysclk.
  • New CPU for Alchemy and Freescale MXS.
  • New CODEC drivers for Analog ADAU1373, Realtek RT5631 and Wolfson MicroelectronicsWM1811 and WM5100.

Syndicated 2012-01-06 19:07:48 from Technicalities

What’s wrong with switch statements?

Recently I’ve been noticing a surprising pattern in code I’m reviewing for the kernel. A lot of people seem to have taken to writing code that I’d expect to look like this:

switch (thing) {
case VALUE:
        /* Stuff */
case BAR:
        /* Nonsense */
        /* Whatever */

with if statements instead:

if (thing == VALUE) {
        /* Stuff */
} else if (thing == BAR) {
        /* Nonsense */
} else {
        /* Whatever */

(where stuff, nonsense and whatever are usually a bit larger). I really don’t understand where this has come from – the if based form isn’t nearly so idiomatic for selecting between a range of values and this seems to have come from nowhere pretty much. Is there some code base out there where this is common practice or something?

Syndicated 2011-12-20 13:24:55 from Technicalities

ASoC updates in 3.1

Linus released version 3.1 of the kernel at Kernel Summit this morning. This has been another fairly quiet release for the framework with a few nice power optimizations, a range of driver enhancements and a fairly small set of new drivers.

  • Lots of cleanups to the register cache code in preparation for moving the code to the regmap API.
  • Support for maintaining lower power when in mostly idle states like microphone detection.
  • Support for weak DAPM routes, enabling better pop/click performance for paths like sidetones.
  • New CODEC drivers for Analog Devices ADAV80x, Sigmatel STA32x and Wolfson WM8728 and WM8983.

Posted from Prague, Prague, Czech Republic.

Syndicated 2011-10-24 09:36:56 from Technicalities

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