linux/sound
Giacomo Guiduzzi 17aaf01933 ALSA: pci: fix reading of swapped values from pcmreg in AC97 codec
Tests 72 and 78 for ALSA in kselftest fail due to reading
inconsistent values from some devices on a VirtualBox
Virtual Machine using the snd_intel8x0 driver for the AC'97
Audio Controller device.
Taking for example test number 72, this is what the test reports:
"Surround Playback Volume.0 expected 1 but read 0, is_volatile 0"
"Surround Playback Volume.1 expected 0 but read 1, is_volatile 0"
These errors repeat for each value from 0 to 31.

Taking a look at these error messages it is possible to notice
that the written values are read back swapped.
When the write is performed, these values are initially stored in
an array used to sanity-check them and write them in the pcmreg
array. To write them, the two one-byte values are packed together
in a two-byte variable through bitwise operations: the first
value is shifted left by one byte and the second value is stored in the
right byte through a bitwise OR. When reading the values back,
right shifts are performed to retrieve the previously stored
bytes. These shifts are executed in the wrong order, thus
reporting the values swapped as shown above.

This patch fixes this mistake by reversing the read
operations' order.

Signed-off-by: Giacomo Guiduzzi <guiduzzi.giacomo@gmail.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220322200653.15862-1-guiduzzi.giacomo@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2022-03-22 21:19:26 +01:00
..
ac97
aoa
arm
atmel
core ALSA: pcm: Add stream lock during PCM reset ioctl operations 2022-03-22 20:57:15 +01:00
drivers ALSA: virmidi: Remove duplicated code 2022-01-06 16:08:18 +01:00
firewire ALSA: firewire-lib: fix uninitialized flag for AV/C deferred transaction 2022-03-04 17:23:21 +01:00
hda ASoC: Updates for v5.18 2022-03-21 16:19:21 +01:00
i2c
isa ALSA: gus: Fix memory leaks at memory allocator error paths 2021-12-13 16:41:12 +01:00
mips ALSA: mips: Use platform_get_irq() to get the interrupt 2022-02-28 16:59:01 +01:00
oss
parisc
pci ALSA: pci: fix reading of swapped values from pcmreg in AC97 codec 2022-03-22 21:19:26 +01:00
pcmcia
ppc ALSA: ppc: beep: fix clang -Wimplicit-fallthrough 2021-12-07 15:36:56 +01:00
sh
soc ASoC: Updates for v5.18 2022-03-21 16:19:21 +01:00
sparc ALSA: sparc: no need to initialise statics to 0 2021-12-12 10:01:04 +01:00
spi ALSA: spi: Add check for clk_enable() 2022-02-28 17:00:10 +01:00
synth
usb Merge branch 'for-next' into for-linus 2022-03-21 16:18:34 +01:00
virtio virtio: wrap config->reset calls 2022-01-14 18:50:52 -05:00
x86 ALSA: x86: Use standard mmap helper for Intel HDMI LPE audio 2022-03-05 09:33:48 +01:00
xen
ac97_bus.c
Kconfig
last.c
Makefile
sound_core.c sound: core: Remove redundant variable and return the last statement 2022-02-28 17:57:14 +01:00