ALSA: emu10k1: fix E-MU dock initialization

A side effect of making the dock monitoring interrupt-driven was that
we'd be very quick to program a freshly connected dock. However, for
unclear reasons, the dock does not work when we do that - despite the
FPGA netlist upload going just fine. We work around this by adding a
delay before programming the dock; for safety, the value is several
times as much as was determined empirically.

Note that a badly timed dock hot-plug would have triggered the problem
even before the referenced commit - but now it would happen 100% instead
of about 3% of the time, thus making it impossible to work around by
re-plugging.

Fixes: fbb64ee ("ALSA: emu10k1: make E-MU dock monitoring interrupt-driven")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=218584
Signed-off-by: Oswald Buddenhagen <[email protected]>
Signed-off-by: Takashi Iwai <[email protected]>
Message-ID: <[email protected]>

Author: ossilator

sound/pci/emu10k1/emu10k1_main.c

@@ -737,6 +737,12 @@ static void snd_emu1010_load_dock_firmware(struct snd_emu10k1 *emu)
 	u32 tmp, tmp2;
 	int err;
 
+	// The docking events clearly arrive prematurely - while the
+	// Dock's FPGA seems to be successfully programmed, the Dock
+	// fails to initialize subsequently if we don't give it some
+	// time to "warm up" here.
+	msleep(200);
+
 	dev_info(emu->card->dev, "emu1010: Loading Audio Dock Firmware\n");
 	/* Return to Audio Dock programming mode */
 	snd_emu1010_fpga_write(emu, EMU_HANA_FPGA_CONFIG,