d7ca3a7154
This is the most significant part in the patch series. The bcm2835-audio driver used to queue the commands to vc04 core via workqueue, but basically the whole accesses to vc04 core are done in the sleepable context, including the callback calls. In such a case, rewriting the code using non-atomic PCM ops will simplify the logic a lot. This patch does it: all workqueue are gone and each former-work implementation is now directly called from PCM ops like trigger and write transfer. Along with it, the DMA position updater, bcm2835_playback_fifo(), was also rewritten to use a simpler logic. Now it handles the XRUN and draining properly by calling snd_pcm_stop() conditionally. The current position is kept in atomic_t value so that it can be read concurrently from the pointer callback. Also, the bcm2835_audio_instance object is allocated at the beginning of bcm2835_audio_open(). This makes the resource management clearer. Signed-off-by: Takashi Iwai <tiwai@suse.de> Tested-by: Stefan Wahren <stefan.wahren@i2se.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
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.