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Benjamin Rood 381679aec2 ASoC: sgtl5000: set DAP_AVC_CTRL register to correct default value on probe
[ Upstream commit f86f58e3594fb0ab1993d833d3b9a2496f3c928c ]

According to the SGTL5000 datasheet [1], the DAP_AVC_CTRL register has
the following bit field definitions:

| BITS  | FIELD       | RW | RESET | DEFINITION                        |
| 15    | RSVD        | RO | 0x0   | Reserved                          |
| 14    | RSVD        | RW | 0x1   | Reserved                          |
| 13:12 | MAX_GAIN    | RW | 0x1   | Max Gain of AVC in expander mode  |
| 11:10 | RSVD        | RO | 0x0   | Reserved                          |
| 9:8   | LBI_RESP    | RW | 0x1   | Integrator Response               |
| 7:6   | RSVD        | RO | 0x0   | Reserved                          |
| 5     | HARD_LMT_EN | RW | 0x0   | Enable hard limiter mode          |
| 4:1   | RSVD        | RO | 0x0   | Reserved                          |
| 0     | EN          | RW | 0x0   | Enable/Disable AVC                |

The original default value written to the DAP_AVC_CTRL register during
sgtl5000_i2c_probe() was 0x0510.  This would incorrectly write values to
bits 4 and 10, which are defined as RESERVED.  It would also not set
bits 12 and 14 to their correct RESET values of 0x1, and instead set
them to 0x0.  While the DAP_AVC module is effectively disabled because
the EN bit is 0, this default value is still writing invalid values to
registers that are marked as read-only and RESERVED as well as not
setting bits 12 and 14 to their correct default values as defined by the
datasheet.

The correct value that should be written to the DAP_AVC_CTRL register is
0x5100, which configures the register bits to the default values defined
by the datasheet, and prevents any writes to bits defined as
'read-only'.  Generally speaking, it is best practice to NOT attempt to
write values to registers/bits defined as RESERVED, as it generally
produces unwanted/undefined behavior, or errors.

Also, all credit for this patch should go to my colleague Dan MacDonald
<dmacdonald@curbellmedical.com> for finding this error in the first
place.

[1] https://www.nxp.com/docs/en/data-sheet/SGTL5000.pdf

Signed-off-by: Benjamin Rood <benjaminjrood@gmail.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Link: https://lore.kernel.org/r/20210219183308.GA2117@ubuntu-dev
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-04-07 14:47:39 +02:00
arch x86/mem_encrypt: Correct physical address calculation in __set_clr_pte_enc() 2021-03-30 14:35:29 +02:00
block block: recalculate segment count for multi-segment discards correctly 2021-03-30 14:35:28 +02:00
certs
crypto crypto: x86 - Regularize glue function prototypes 2021-03-20 10:39:47 +01:00
Documentation KVM: arm64: Reject VM creation when the default IPA size is unsupported 2021-03-17 17:03:57 +01:00
drivers xen-blkback: don't leak persistent grants from xen_blkbk_map() 2021-03-30 14:35:30 +02:00
fs iomap: Fix negative assignment to unsigned sis->pages in iomap_swapfile_activate 2021-04-07 14:47:38 +02:00
include can: dev: Move device back to init netns on owning netns delete 2021-03-30 14:35:29 +02:00
init
ipc
kernel module: harden ELF info handling 2021-04-07 14:47:38 +02:00
lib
LICENSES
mm hugetlbfs: hugetlb_fault_mutex_hash() cleanup 2021-03-30 14:35:19 +02:00
net rpc: fix NULL dereference on kmalloc failure 2021-04-07 14:47:38 +02:00
samples
scripts
security integrity: double check iint_cache was initialized 2021-03-30 14:35:24 +02:00
sound ASoC: sgtl5000: set DAP_AVC_CTRL register to correct default value on probe 2021-04-07 14:47:39 +02:00
tools perf auxtrace: Fix auxtrace queue conflict 2021-03-30 14:35:28 +02:00
usr
virt KVM: arm64: Ensure I-cache isolation between vcpus of a same VM 2021-03-17 17:03:57 +01:00
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Makefile Linux 5.4.109 2021-03-30 14:35:30 +02:00
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