ASoC: da7219: Flush pending AAD IRQ when suspending

ASoC: da7219: Flush pending AAD IRQ when suspending

da7219_aad_suspend() disables jack detection, which should prevent
generating new interrupts by DA7219 while suspended. However, there is a
theoretical possibility that there is a pending interrupt generated just
before suspending DA7219 and not handled yet, so the IRQ handler may
still run after DA7219 is suspended. To prevent that, wait until the
pending IRQ handling is done.

This patch arose as an attempt to fix the following I2C failure
occurring sometimes during system suspend or resume:

[  355.876211] i2c_designware i2c_designware.3: Transfer while suspended
[  355.876245] WARNING: CPU: 2 PID: 3576 at drivers/i2c/busses/i2c-designware-master.c:570 i2c_dw_xfer+0x411/0x440
...
[  355.876462] Call Trace:
[  355.876468]  <TASK>
[  355.876475]  ? update_load_avg+0x1b3/0x615
[  355.876484]  __i2c_transfer+0x101/0x1d8
[  355.876494]  i2c_transfer+0x74/0x10d
[  355.876504]  regmap_i2c_read+0x6a/0x9c
[  355.876513]  _regmap_raw_read+0x179/0x223
[  355.876521]  regmap_raw_read+0x1e1/0x28e
[  355.876527]  regmap_bulk_read+0x17d/0x1ba
[  355.876532]  ? __wake_up+0xed/0x1bb
[  355.876542]  da7219_aad_irq_thread+0x54/0x2c9 [snd_soc_da7219 5fb8ebb2179cf2fea29af090f3145d68ed8e2184]
[  355.876556]  irq_thread+0x13c/0x231
[  355.876563]  ? irq_forced_thread_fn+0x5f/0x5f
[  355.876570]  ? irq_thread_fn+0x4d/0x4d
[  355.876576]  kthread+0x13a/0x152
[  355.876581]  ? synchronize_irq+0xc3/0xc3
[  355.876587]  ? kthread_blkcg+0x31/0x31
[  355.876592]  ret_from_fork+0x1f/0x30
[  355.876601]  </TASK>

which indicates that the AAD IRQ handler is unexpectedly running when
DA7219 is suspended, and as a result, is trying to read data from DA7219
over I2C and is hitting the I2C driver "Transfer while suspended"
failure.

However, with this patch the above failure is still reproducible. So
this patch does not fix any real observed issue so far, but at least is
useful for confirming that the above issue is not caused by a pending
IRQ but rather looks like a DA7219 hardware issue with an IRQ
unexpectedly generated after jack detection is already disabled.

Signed-off-by: Dmytro Maluka <dmy@semihalf.com>
Link: https://lore.kernel.org/r/20230717193737.161784-2-dmy@semihalf.com
Signed-off-by: Mark Brown <broonie@kernel.org>