linux-imx

ASoC: rsnd: fixup not to call clk_get/set under non-atomic

Clocking operations clk_get/set_rate, are non-atomic,
they shouldn't be called in soc_pcm_trigger() which is atomic.

Following issue was found due to execution of clk_get_rate() causes
sleep in soc_pcm_trigger(), which shouldn't be blocked.

We can reproduce this issue by following
	> enable CONFIG_DEBUG_ATOMIC_SLEEP=y
	> compile, and boot
	> mount -t debugfs none /sys/kernel/debug
	> while true; do cat /sys/kernel/debug/clk/clk_summary > /dev/null; done &
	> while true; do aplay xxx; done

This patch adds support to .prepare callback, and moves non-atomic
clocking operations to it. As .prepare is non-atomic, it is always
called before trigger_start/trigger_stop.

	BUG: sleeping function called from invalid context at kernel/locking/mutex.c:620
	in_atomic(): 1, irqs_disabled(): 128, pid: 2242, name: aplay
	INFO: lockdep is turned off.
	irq event stamp: 5964
	hardirqs last enabled at (5963): [<ffff200008e59e40>] mutex_lock_nested+0x6e8/0x6f0
	hardirqs last disabled at (5964): [<ffff200008e623f0>] _raw_spin_lock_irqsave+0x24/0x68
	softirqs last enabled at (5502): [<ffff200008081838>] __do_softirq+0x560/0x10c0
	softirqs last disabled at (5495): [<ffff2000080c2e78>] irq_exit+0x160/0x25c
	Preemption disabled at:[ 62.904063] [<ffff200008be4d48>] snd_pcm_stream_lock+0xb4/0xc0
	CPU: 2 PID: 2242 Comm: aplay Tainted: G B C 4.9.54+ #186
	Hardware name: Renesas Salvator-X board based on r8a7795 (DT)
	Call trace:
	[<ffff20000808fe48>] dump_backtrace+0x0/0x37c
	[<ffff2000080901d8>] show_stack+0x14/0x1c
	[<ffff2000086f4458>] dump_stack+0xfc/0x154
	[<ffff2000081134a0>] ___might_sleep+0x57c/0x58c
	[<ffff2000081136b8>] __might_sleep+0x208/0x21c
	[<ffff200008e5980c>] mutex_lock_nested+0xb4/0x6f0
	[<ffff2000087cac74>] clk_prepare_lock+0xb0/0x184
	[<ffff2000087cb094>] clk_core_get_rate+0x14/0x54
	[<ffff2000087cb0f4>] clk_get_rate+0x20/0x34
	[<ffff20000113aa00>] rsnd_adg_ssi_clk_try_start+0x158/0x4f8 [snd_soc_rcar]
	[<ffff20000113da00>] rsnd_ssi_init+0x668/0x7a0 [snd_soc_rcar]
	[<ffff200001133ff4>] rsnd_soc_dai_trigger+0x4bc/0xcf8 [snd_soc_rcar]
	[<ffff200008c1af24>] soc_pcm_trigger+0x2a4/0x2d4

Fixes: e7d850dd10f4 ("ASoC: rsnd: use mod base common method on SSI-parent")
Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
Signed-off-by: Timo Wischer <twischer@de.adit-jv.com>
[Kuninori: tidyup for upstream]
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Tested-by: Hiroyuki Yokoyama <hiroyuki.yokoyama.vx@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org