ASoC: samsung: Prevent clk_get_rate() calls in atomic context

This patch moves clk_get_rate() call from trigger() to hw_params()
callback to avoid calling sleeping clk API from atomic context
and prevent deadlock as indicated below.

Before this change clk_get_rate() was being called with same
spinlock held as the one passed to the clk API when registering
clocks exposed by the I2S driver.

[   82.109780] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:908
[   82.117009] in_atomic(): 1, irqs_disabled(): 128, pid: 1554, name: speaker-test
[   82.124235] 3 locks held by speaker-test/1554:
[   82.128653]  #0: cc8c5328 (snd_pcm_link_rwlock){...-}, at: snd_pcm_stream_lock_irq+0x20/0x38
[   82.137058]  #1: ec9eda17 (&(&substream->self_group.lock)->rlock){..-.}, at: snd_pcm_ioctl+0x900/0x1268
[   82.146417]  #2: 6ac279bf (&(&pri_dai->spinlock)->rlock){..-.}, at: i2s_trigger+0x64/0x6d4
[   82.154650] irq event stamp: 8144
[   82.157949] hardirqs last  enabled at (8143): [<c0a0f574>] _raw_read_unlock_irq+0x24/0x5c
[   82.166089] hardirqs last disabled at (8144): [<c0a0f6a8>] _raw_read_lock_irq+0x18/0x58
[   82.174063] softirqs last  enabled at (8004): [<c01024e4>] __do_softirq+0x3a4/0x66c
[   82.181688] softirqs last disabled at (7997): [<c012d730>] irq_exit+0x140/0x168
[   82.188964] Preemption disabled at:
[   82.188967] [<00000000>]   (null)
[   82.195728] CPU: 6 PID: 1554 Comm: speaker-test Not tainted 5.0.0-rc5-00192-ga6e6caca8f03 #191
[   82.204302] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[   82.210376] [<c0111a54>] (unwind_backtrace) from [<c010d8f4>] (show_stack+0x10/0x14)
[   82.218084] [<c010d8f4>] (show_stack) from [<c09ef004>] (dump_stack+0x90/0xc8)
[   82.225278] [<c09ef004>] (dump_stack) from [<c0152980>] (___might_sleep+0x22c/0x2c8)
[   82.232990] [<c0152980>] (___might_sleep) from [<c0a0a2e4>] (__mutex_lock+0x28/0xa3c)
[   82.240788] [<c0a0a2e4>] (__mutex_lock) from [<c0a0ad80>] (mutex_lock_nested+0x1c/0x24)
[   82.248763] [<c0a0ad80>] (mutex_lock_nested) from [<c04923dc>] (clk_prepare_lock+0x78/0xec)
[   82.257079] [<c04923dc>] (clk_prepare_lock) from [<c049538c>] (clk_core_get_rate+0xc/0x5c)
[   82.265309] [<c049538c>] (clk_core_get_rate) from [<c0766b18>] (i2s_trigger+0x490/0x6d4)
[   82.273369] [<c0766b18>] (i2s_trigger) from [<c074fec4>] (soc_pcm_trigger+0x100/0x140)
[   82.281254] [<c074fec4>] (soc_pcm_trigger) from [<c07378a0>] (snd_pcm_do_start+0x2c/0x30)
[   82.289400] [<c07378a0>] (snd_pcm_do_start) from [<c07376cc>] (snd_pcm_action_single+0x38/0x78)
[   82.298065] [<c07376cc>] (snd_pcm_action_single) from [<c073a450>] (snd_pcm_ioctl+0x910/0x1268)
[   82.306734] [<c073a450>] (snd_pcm_ioctl) from [<c0292344>] (do_vfs_ioctl+0x90/0x9ec)
[   82.314443] [<c0292344>] (do_vfs_ioctl) from [<c0292cd4>] (ksys_ioctl+0x34/0x60)
[   82.321808] [<c0292cd4>] (ksys_ioctl) from [<c0101000>] (ret_fast_syscall+0x0/0x28)
[   82.329431] Exception stack(0xeb875fa8 to 0xeb875ff0)
[   82.334459] 5fa0:                   00033c18 b6e31000 00000004 00004142 00033d80 00033d80
[   82.342605] 5fc0: 00033c18 b6e31000 00008000 00000036 00008000 00000000 beea38a8 00008000
[   82.350748] 5fe0: b6e3142c beea384c b6da9a30 b6c9212c
[   82.355789]
[   82.357245] ======================================================
[   82.363397] WARNING: possible circular locking dependency detected
[   82.369551] 5.0.0-rc5-00192-ga6e6caca8f03 #191 Tainted: G        W
[   82.376395] ------------------------------------------------------
[   82.382548] speaker-test/1554 is trying to acquire lock:
[   82.387834] 6d2007f4 (prepare_lock){+.+.}, at: clk_prepare_lock+0x78/0xec
[   82.394593]
[   82.394593] but task is already holding lock:
[   82.400398] 6ac279bf (&(&pri_dai->spinlock)->rlock){..-.}, at: i2s_trigger+0x64/0x6d4
[   82.408197]
[   82.408197] which lock already depends on the new lock.
[   82.416343]
[   82.416343] the existing dependency chain (in reverse order) is:
[   82.423795]
[   82.423795] -> #1 (&(&pri_dai->spinlock)->rlock){..-.}:
[   82.430472]        clk_mux_set_parent+0x34/0xb8
[   82.434975]        clk_core_set_parent_nolock+0x1c4/0x52c
[   82.440347]        clk_set_parent+0x38/0x6c
[   82.444509]        of_clk_set_defaults+0xc8/0x308
[   82.449186]        of_clk_add_provider+0x84/0xd0
[   82.453779]        samsung_i2s_probe+0x408/0x5f8
[   82.458376]        platform_drv_probe+0x48/0x98
[   82.462879]        really_probe+0x224/0x3f4
[   82.467037]        driver_probe_device+0x70/0x1c4
[   82.471716]        bus_for_each_drv+0x44/0x8c
[   82.476049]        __device_attach+0xa0/0x138
[   82.480382]        bus_probe_device+0x88/0x90
[   82.484715]        deferred_probe_work_func+0x6c/0xbc
[   82.489741]        process_one_work+0x200/0x740
[   82.494246]        worker_thread+0x2c/0x4c8
[   82.498408]        kthread+0x128/0x164
[   82.502131]        ret_from_fork+0x14/0x20
[   82.506204]          (null)
[   82.508976]
[   82.508976] -> #0 (prepare_lock){+.+.}:
[   82.514264]        __mutex_lock+0x60/0xa3c
[   82.518336]        mutex_lock_nested+0x1c/0x24
[   82.522756]        clk_prepare_lock+0x78/0xec
[   82.527088]        clk_core_get_rate+0xc/0x5c
[   82.531421]        i2s_trigger+0x490/0x6d4
[   82.535494]        soc_pcm_trigger+0x100/0x140
[   82.539913]        snd_pcm_do_start+0x2c/0x30
[   82.544246]        snd_pcm_action_single+0x38/0x78
[   82.549012]        snd_pcm_ioctl+0x910/0x1268
[   82.553345]        do_vfs_ioctl+0x90/0x9ec
[   82.557417]        ksys_ioctl+0x34/0x60
[   82.561229]        ret_fast_syscall+0x0/0x28
[   82.565477]        0xbeea384c
[   82.568421]
[   82.568421] other info that might help us debug this:
[   82.568421]
[   82.576394]  Possible unsafe locking scenario:
[   82.576394]
[   82.582285]        CPU0                    CPU1
[   82.586792]        ----                    ----
[   82.591297]   lock(&(&pri_dai->spinlock)->rlock);
[   82.595977]                                lock(prepare_lock);
[   82.601782]                                lock(&(&pri_dai->spinlock)->rlock);
[   82.608975]   lock(prepare_lock);
[   82.612268]
[   82.612268]  *** DEADLOCK ***

Fixes: 647d04f8 ("ASoC: samsung: i2s: Ensure the RCLK rate is properly determined")
Reported-by: Krzysztof Kozłowski <krzk@kernel.org>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/samsung/i2s.c

@@ -700,6 +700,7 @@ static int i2s_hw_params(struct snd_pcm_substream *substream,
 {
 	struct i2s_dai *i2s = to_info(dai);
 	u32 mod, mask = 0, val = 0;
+	struct clk *rclksrc;
 	unsigned long flags;
 
 	WARN_ON(!pm_runtime_active(dai->dev));
@@ -782,6 +783,10 @@ static int i2s_hw_params(struct snd_pcm_substream *substream,
 
 	i2s->frmclk = params_rate(params);
 
+	rclksrc = i2s->clk_table[CLK_I2S_RCLK_SRC];
+	if (rclksrc && !IS_ERR(rclksrc))
+		i2s->rclk_srcrate = clk_get_rate(rclksrc);
+
 	return 0;
 }
 
@@ -886,11 +891,6 @@ static int config_setup(struct i2s_dai *i2s)
 		return 0;
 
 	if (!(i2s->quirks & QUIRK_NO_MUXPSR)) {
-		struct clk *rclksrc = i2s->clk_table[CLK_I2S_RCLK_SRC];
-
-		if (rclksrc && !IS_ERR(rclksrc))
-			i2s->rclk_srcrate = clk_get_rate(rclksrc);
-
 		psr = i2s->rclk_srcrate / i2s->frmclk / rfs;
 		writel(((psr - 1) << 8) | PSR_PSREN, i2s->addr + I2SPSR);
 		dev_dbg(&i2s->pdev->dev,