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4d024fe8f8
It turned out that the recent simplification of HD-audio bus access
helpers caused a regression on the virtual HD-audio device on QEMU
with ARM platforms. The driver got a CORB/RIRB timeout and couldn't
probe any codecs.
The essential difference that caused a problem was the enforced
aligned MMIO accesses by simplification. Since snd-hda-tegra driver
is enabled on ARM, it enables CONFIG_SND_HDA_ALIGNED_MMIO, which makes
the all HD-audio drivers using the aligned MMIO accesses. While this
is mandatory for snd-hda-tegra, it seems that snd-hda-intel on ARM
gets broken by this access pattern.
For addressing the regression, this patch introduces a new flag,
aligned_mmio, to hdac_bus object, and applies the aligned MMIO only
when this flag is set. This change affects only platforms with
CONFIG_SND_HDA_ALIGNED_MMIO set, i.e. mostly only for ARM platforms.
Unfortunately the patch became a big bigger than it should be, just
because the former calls didn't take hdac_bus object in the argument,
hence we had to extend the call patterns.
Fixes: 19abfefd4c ("ALSA: hda: Direct MMIO accesses")
BugLink: https://bugzilla.opensuse.org/show_bug.cgi?id=1161152
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200120104127.28985-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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.
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.