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Katsuhiro Suzuki 2c8340cad6 clk: fractional-divider: check parent rate only if flag is set 
[ Upstream commit d13501a2be ]

Custom approximation of fractional-divider may not need parent clock
rate checking. For example Rockchip SoCs work fine using grand parent
clock rate even if target rate is greater than parent.

This patch checks parent clock rate only if CLK_SET_RATE_PARENT flag
is set.

For detailed example, clock tree of Rockchip I2S audio hardware.
  - Clock rate of CPLL is 1.2GHz, GPLL is 491.52MHz.
  - i2s1_div is integer divider can divide N (N is 1~128).
    Input clock is CPLL or GPLL. Initial divider value is N = 1.
    Ex) PLL = CPLL, N = 10, i2s1_div output rate is
      CPLL / 10 = 1.2GHz / 10 = 120MHz
  - i2s1_frac is fractional divider can divide input to x/y, x and
    y are 16bit integer.

CPLL --> | selector | ---> i2s1_div -+--> | selector | --> I2S1 MCLK
GPLL --> |          | ,--------------'    |          |
                      `--> i2s1_frac ---> |          |

Clock mux system try to choose suitable one from i2s1_div and
i2s1_frac for master clock (MCLK) of I2S1.

Bad scenario as follows:
  - Try to set MCLK to 8.192MHz (32kHz audio replay)
    Candidate setting is
    - i2s1_div: GPLL / 60 = 8.192MHz
    i2s1_div candidate is exactly same as target clock rate, so mux
    choose this clock source. i2s1_div output rate is changed
    491.52MHz -> 8.192MHz

  - After that try to set to 11.2896MHz (44.1kHz audio replay)
    Candidate settings are
    - i2s1_div : CPLL / 107 = 11.214945MHz
    - i2s1_frac: i2s1_div   = 8.192MHz
      This is because clk_fd_round_rate() thinks target rate
      (11.2896MHz) is higher than parent rate (i2s1_div = 8.192MHz)
      and returns parent clock rate.

Above is current upstreamed behavior. Clock mux system choose
i2s1_div, but this clock rate is not acceptable for I2S driver, so
users cannot replay audio.

Expected behavior is:
  - Try to set master clock to 11.2896MHz (44.1kHz audio replay)
    Candidate settings are
    - i2s1_div : CPLL / 107          = 11.214945MHz
    - i2s1_frac: i2s1_div * 147/6400 = 11.2896MHz
                 Change i2s1_div to GPLL / 1 = 491.52MHz at same
                 time.

If apply this commit, clk_fd_round_rate() calls custom approximate
function of Rockchip even if target rate is higher than parent.
Custom function changes both grand parent (i2s1_div) and parent
(i2s_frac) settings at same time. Clock mux system can choose
i2s1_frac and audio works fine.

Signed-off-by: Katsuhiro Suzuki <katsuhiro@katsuster.net>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
[sboyd@kernel.org: Make function into a macro instead]
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-04-05 22:31:31 +02:00
arch powerpc/hugetlb: Handle mmap_min_addr correctly in get_unmapped_area callback 2019-04-05 22:31:30 +02:00
block blk-mq: fix a hung issue when fsync 2019-02-20 10:20:44 +01:00
certs Replace magic for trusting the secondary keyring with #define 2018-09-09 19:55:54 +02:00
crypto crypto: pcbc - remove bogus memcpy()s with src == dest 2019-03-23 14:35:21 +01:00
Documentation KVM: Reject device ioctls from processes other than the VM's creator 2019-04-03 06:25:20 +02:00
drivers clk: fractional-divider: check parent rate only if flag is set 2019-04-05 22:31:31 +02:00
firmware License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fs fs: fix guard_bio_eod to check for real EOD errors 2019-04-05 22:31:28 +02:00
include clk: fractional-divider: check parent rate only if flag is set 2019-04-05 22:31:31 +02:00
init Revert "mm: use early_pfn_to_nid in page_ext_init" 2019-03-23 14:35:13 +01:00
ipc ipc/sem.c: prevent queue.status tearing in semop 2018-09-05 09:26:30 +02:00
kernel sysctl: handle overflow for file-max 2019-04-05 22:31:26 +02:00
lib lib/int_sqrt: optimize initial value compute 2019-04-05 22:31:24 +02:00
mm page_poison: play nicely with KASAN 2019-04-05 22:31:28 +02:00
net tcp: do not use ipv6 header for ipv4 flow 2019-04-03 06:25:09 +02:00
samples samples: mei: use /dev/mei0 instead of /dev/mei 2019-02-15 08:09:12 +01:00
scripts kbuild: modversions: Fix relative CRC byte order interpretation 2019-04-03 06:25:17 +02:00
security security/selinux: fix SECURITY_LSM_NATIVE_LABELS on reused superblock 2019-03-23 14:35:26 +01:00
sound ALSA: hda/realtek - Add support headset mode for New DELL WYSE NB 2019-04-03 06:25:16 +02:00
tools tools lib traceevent: Fix buffer overflow in arg_eval 2019-04-05 22:31:29 +02:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt KVM: Reject device ioctls from processes other than the VM's creator 2019-04-03 06:25:20 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: rpm-pkg: keep spec file until make mrproper 2018-02-13 10:19:46 +01:00
.mailmap .mailmap: Add Maciej W. Rozycki's Imagination e-mail address 2017-11-10 12:16:15 -08:00
COPYING
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS MAINTAINERS: Add Sasha as a stable branch maintainer 2018-12-01 09:42:50 +01:00
Makefile Linux 4.14.110 2019-04-03 06:25:21 +02:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

README 

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

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.