Giacomo Guiduzzi c2052ad0c7 ALSA: pci: fix reading of swapped values from pcmreg in AC97 codec ... commit 17aaf01933 upstream. 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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2022-03-28 09:58:44 +02:00
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Makefile	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00
ac97_codec.c	ALSA: pci: fix reading of swapped values from pcmreg in AC97 codec	2022-03-28 09:58:44 +02:00
ac97_id.h	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156	2019-05-30 11:26:35 -07:00
ac97_local.h	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156	2019-05-30 11:26:35 -07:00
ac97_patch.c	ALSA: ac97: Fix assignment in if condition	2021-06-09 17:30:02 +02:00
ac97_patch.h	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156	2019-05-30 11:26:35 -07:00
ac97_pcm.c	ALSA: ac97: More constifications	2020-01-05 16:14:34 +01:00
ac97_proc.c	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156	2019-05-30 11:26:35 -07:00