[v2,0/3] clk: Fix issues related to CLK_IGNORE_UNUSED failures and amlogic glitch free mux

Message

Chuan Liu via B4 Relay Nov. 11, 2024, 3:37 a.m. UTC

If CLK_OPS_PARENT_ENABLE is configured for clock,
clk_core_disable_unprepare() is called in clk_disable_unused_subtree().
Even clocks that are configured with CLK_IGNORE_UNUSED are disabled,
resulting in the failure of CLK_IGNORE_UNUSED.

To ensure that amlogic glitch free mux can switch clock channels
properly, add flag CLK_OPS_PARENT_ENABLE to glitch free mux. The issue
that CLK_OPS_PARENT_ENABLE in CCF causes CLK_IGNORE_UNUSED to fail is
also exposed.

glitch free mux channel switchover failure issue(Test vpu_clk on S4):
step 1:
$ cat /sys/kernel/debug/clk/vpu/clk_parent 
vpu_0
$ cat /sys/kernel/debug/clk/vpu_0/clk_rate 
399999994
$ cat /sys/kernel/debug/clk/vpu_1/clk_rate 
666666656
$ echo 1 > /sys/kernel/debug/clk/vpu/clk_prepare_enable 
$ cat /sys/kernel/debug/meson-clk-msr/clks/cts_vpu_clk
399987500       +/-12500Hz

step 2:
$ echo 0 > /sys/kernel/debug/clk/vpu/clk_prepare_enable 
$ echo 1 > /sys/kernel/debug/clk/vpu/clk_parent 
$ cat /sys/kernel/debug/clk/vpu/clk_parent 
vpu_1
$ cat /sys/kernel/debug/clk/vpu/clk_rate 
666666656
$ echo 1 > /sys/kernel/debug/clk/vpu/clk_prepare_enable 
$ cat /sys/kernel/debug/meson-clk-msr/clks/cts_vpu_clk
0       +/-3125Hz

In step2, vpu_0 is disabled, and the vpu is not switched to vpu_1. At
this time, the vpu is still connected to vpu_0 and vpu_0 is disabled at
this time, resulting in the clk-measure not measuring the clock.

Signed-off-by: Chuan Liu <[e-mail]>
---
Changes in v2:
- The failure of glitch-free mux switching and the suppression of glitch
are split into two patch.
- The glitch-free mux adds support for the meson-8 family.
- Link to v1: https://lore.kernel.org/r/[e-mail]

---
Chuan Liu (3):
      clk: Fix the CLK_IGNORE_UNUSED failure issue
      clk: meson: Fix failure of glitch-free mux switching
      clk: meson: Fix glitch occurs when setting up glitch-free mux

 drivers/clk/clk.c                  | 67 ++++++++++++++++++++++++++++++++++++--
 drivers/clk/meson/a1-peripherals.c | 12 +++----
 drivers/clk/meson/axg.c            | 16 +++++----
 drivers/clk/meson/c3-peripherals.c |  6 ++--
 drivers/clk/meson/g12a.c           | 18 ++++++----
 drivers/clk/meson/gxbb.c           | 18 ++++++----
 drivers/clk/meson/meson8b.c        | 21 ++++++++++--
 drivers/clk/meson/s4-peripherals.c | 32 +++++++++---------
 8 files changed, 140 insertions(+), 50 deletions(-)
---
base-commit: 664988eb47dd2d6ae1d9e4188ec91832562f8f26
change-id: 20240929-fix_glitch_free-290c88923c31

Best regards,