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clk: meson: change usleep_range() to udelay() for atomic context

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The function meson_clk_pll_enable() can be invoked under the enable_lock
spinlock from the clk core logic, which risks a kernel panic during the
usleep_range() call:

   BUG: scheduling while atomic: kworker/u4:2/36/0x00000002
   Modules linked in: g_ffs usb_f_fs libcomposite
   CPU: 1 PID: 36 Comm: kworker/u4:2 Not tainted 6.4.0-rc5 #273
   Workqueue: events_unbound async_run_entry_fn
   Call trace:
    dump_backtrace+0x9c/0x128
    show_stack+0x20/0x38
    dump_stack_lvl+0x48/0x60
    dump_stack+0x18/0x28
    __schedule_bug+0x58/0x78
    __schedule+0x828/0xa88
    schedule+0x64/0xd8
    schedule_hrtimeout_range_clock+0xd0/0x208
    schedule_hrtimeout_range+0x1c/0x30
    usleep_range_state+0x6c/0xa8
    meson_clk_pll_enable+0x1f4/0x310
    clk_core_enable+0x78/0x200
    clk_core_enable+0x58/0x200
    clk_core_enable+0x58/0x200
    clk_core_enable+0x58/0x200
    clk_enable+0x34/0x60

So it is required to use the udelay() function instead of usleep_range()
for the atomic context safety.

Fixes: b6ec400aa1 ("clk: meson: introduce new pll power-on sequence for A1 SoC family")
Reported-by: Jan Dakinevich <yvdakinevich@sberdevices.ru>
Signed-off-by: Dmitry Rokosov <ddrokosov@sberdevices.ru>
Link: https://lore.kernel.org/r/20230704215404.11533-1-ddrokosov@sberdevices.ru
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
This commit is contained in:
Dmitry Rokosov 2023-07-05 00:54:04 +03:00 committed by Jerome Brunet
parent 06c2afb862
commit 6e2acbfe59
1 changed files with 2 additions and 2 deletions
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4
drivers/clk/meson/clk-pll.c
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@ -367,9 +367,9 @@ static int meson_clk_pll_enable(struct clk_hw *hw)
* 3. enable the lock detect module
*/
if (MESON_PARM_APPLICABLE(&pll->current_en)) {
usleep_range(10, 20);
udelay(10);
meson_parm_write(clk->map, &pll->current_en, 1);
usleep_range(40, 50);
udelay(40);
}
if (MESON_PARM_APPLICABLE(&pll->l_detect)) {