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Martin Blumenstingl df29c01b9f clk: meson: gxbb: Fix the SDM_EN bit for MPLL0 on GXBB 
[ Upstream commit ff54938dd1 ]

There are reports that 48kHz audio does not work on the WeTek Play 2
(which uses a GXBB SoC), while 44.1kHz audio works fine on the same
board. There are also reports of 48kHz audio working fine on GXL and
GXM SoCs, which are using an (almost) identical AIU (audio controller).

Experimenting has shown that MPLL0 is causing this problem. In the .dts
we have by default:
	assigned-clocks = <&clkc CLKID_MPLL0>,
			  <&clkc CLKID_MPLL1>,
			  <&clkc CLKID_MPLL2>;
	assigned-clock-rates = <294912000>,
			       <270950400>,
			       <393216000>;
The MPLL0 rate is divisible by 48kHz without remainder and the MPLL1
rate is divisible by 44.1kHz without remainder. Swapping these two clock
rates "fixes" 48kHz audio but breaks 44.1kHz audio.

Everything looks normal when looking at the info provided by the common
clock framework while playing 48kHz audio (via I2S with mclk-fs = 256):
        mpll_prediv                 1        1        0  2000000000
           mpll0_div                1        1        0   294909641
              mpll0                 1        1        0   294909641
                 cts_amclk_sel       1        1        0   294909641
                    cts_amclk_div       1        1        0    12287902
                       cts_amclk       1        1        0    12287902

meson-clk-msr however shows that the actual MPLL0 clock is off by more
than 38MHz:
        mp0_out               333322917    +/-10416Hz

The rate seen by meson-clk-msr is very close to what we would get when
SDM (the fractional part) was ignored:
  (2000000000Hz * 16384) / ((16384 * 6) = 333.33MHz
If SDM was considered the we should get close to:
  (2000000000Hz * 16384) / ((16384 * 6) + 12808) = 294.9MHz

Further experimenting shows that HHI_MPLL_CNTL7[15] does not have any
effect on the rate of MPLL0 as seen my meson-clk-msr (regardless of
whether that bit is zero or one the rate is always the same according to
meson-clk-msr). Using HHI_MPLL_CNTL[25] on the other hand as SDM_EN
results in SDM being considered for the rate output by the hardware. The
rate - as seen by meson-clk-msr - matches with what we expect when
SDM_EN is enabled (fractional part is being considered, resulting in a
294.9MHz output) or disable (fractional part being ignored, resulting in
a 333.33MHz output).

Reported-by: Christian Hewitt <christianshewitt@gmail.com>
Tested-by: Christian Hewitt <christianshewitt@gmail.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Link: https://lore.kernel.org/r/20211031135006.1508796-1-martin.blumenstingl@googlemail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-01-27 10:54:21 +01:00
arch powerpc/smp: Move setup_profiling_timer() under CONFIG_PROFILING 2022-01-27 10:54:21 +01:00
block scsi: block: pm: Always set request queue runtime active in blk_post_runtime_resume() 2022-01-27 10:54:08 +01:00
certs certs: Trigger creation of RSA module signing key if it's not an RSA key 2021-09-15 09:50:29 +02:00
crypto crypto: jitter - consider 32 LSB for APT 2022-01-27 10:54:12 +01:00
Documentation counter: stm32-lptimer-cnt: remove iio counter abi 2022-01-27 10:54:08 +01:00
drivers clk: meson: gxbb: Fix the SDM_EN bit for MPLL0 on GXBB 2022-01-27 10:54:21 +01:00
fs btrfs: remove BUG_ON(!eie) in find_parent_nodes 2022-01-27 10:54:19 +01:00
include ACPICA: actypes.h: Expand the ACPI_ACCESS_ definitions 2022-01-27 10:54:18 +01:00
init bpf: Add kconfig knob for disabling unpriv bpf by default 2022-01-05 12:40:34 +01:00
ipc shm: extend forced shm destroy to support objects from several IPC nses 2021-12-01 09:19:10 +01:00
kernel audit: ensure userspace is penalized the same as the kernel when under pressure 2022-01-27 10:54:16 +01:00
lib lib/mpi: Add the return value check of kcalloc() 2022-01-27 10:54:02 +01:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm shmem: fix a race between shmem_unused_huge_shrink and shmem_evict_inode 2022-01-27 10:53:44 +01:00
net mac80211: allow non-standard VHT MCS-10/11 2022-01-27 10:54:19 +01:00
samples ftrace/samples: Add missing prototypes direct functions 2022-01-11 15:25:00 +01:00
scripts recordmcount.pl: fix typo in s390 mcount regex 2022-01-05 12:40:29 +01:00
security selinux: fix potential memleak in selinux_add_opt() 2022-01-27 10:53:58 +01:00
sound ASoC: fsl_asrc: refine the check of available clock divider 2022-01-27 10:54:09 +01:00
tools selftests/ftrace: make kprobe profile testcase description unique 2022-01-27 10:54:15 +01:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt KVM: downgrade two BUG_ONs to WARN_ON_ONCE 2021-12-22 09:30:50 +01:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore kbuild: generate Module.symvers only when vmlinux exists 2021-05-19 10:12:59 +02:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: adjust GCC PLUGINS after gcc-plugin.sh removal 2021-12-14 11:32:46 +01:00
Makefile Linux 5.10.93 2022-01-20 09:17:52 +01:00
README

README 

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.