ALSA: emu10k1: use mutex for E-MU FPGA access locking

The FPGA access through the GPIO port does not interfere with other
sound processor register access, so there is no need to subject it to
emu_lock. And after moving all FPGA access out of the interrupt handler,
it does not need to be IRQ-safe, either.

What's more, attaching the dock causes a firmware upload, which takes
several seconds. We really don't want to disable IRQs for this long, and
even less also have someone else spin with IRQs disabled waiting for us.

Therefore, use a mutex for FPGA access locking.

This makes the code somewhat more noisy, as we need to wrap bigger
sections into the mutex, as it needs to enclose the spinlocks.

The latter has the "side effect" of fixing dock FPGA programming in a
corner case: a really badly timed mixer access right between entering
FPGA programming mode and uploading the netlist would mess up the
protocol.

Signed-off-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Message-ID: <20240428093716.3198666-5-oswald.buddenhagen@gmx.de>

1 files changed, 15 insertions, 4 deletions

diff --git a/sound/pci/emu10k1/emu10k1_main.c b/sound/pci/emu10k1/emu10k1_main.c
index 86eaf5963502..1a2905e8672b 100644
--- a/sound/pci/emu10k1/emu10k1_main.c
+++ b/sound/pci/emu10k1/emu10k1_main.c
@@ -810,6 +810,8 @@ static void emu1010_work(struct work_struct *work)
 		return;
 #endif
 
+	snd_emu1010_fpga_lock(emu);
+
 	snd_emu1010_fpga_read(emu, EMU_HANA_IRQ_STATUS, &sts);
 
 	// The distinction of the IRQ status bits is unreliable,
@@ -819,6 +821,8 @@ static void emu1010_work(struct work_struct *work)
 
 	if (sts & EMU_HANA_IRQ_WCLK_CHANGED)
 		emu1010_clock_event(emu);
+
+	snd_emu1010_fpga_unlock(emu);
 }
 
 static void emu1010_interrupt(struct snd_emu10k1 *emu)
@@ -852,6 +856,8 @@ static int snd_emu10k1_emu1010_init(struct snd_emu10k1 *emu)
 	 * Proper init follows in snd_emu10k1_init(). */
 	outl(HCFG_LOCKSOUNDCACHE | HCFG_LOCKTANKCACHE_MASK, emu->port + HCFG);
 
+	snd_emu1010_fpga_lock(emu);
+
 	/* Disable 48Volt power to Audio Dock */
 	snd_emu1010_fpga_write(emu, EMU_HANA_DOCK_PWR, 0);
 
@@ -877,7 +883,7 @@ static int snd_emu10k1_emu1010_init(struct snd_emu10k1 *emu)
 	err = snd_emu1010_load_firmware(emu, 0, &emu->firmware);
 	if (err < 0) {
 		dev_info(emu->card->dev, "emu1010: Loading Firmware failed\n");
-		return err;
+		goto fail;
 	}
 
 	/* ID, should read & 0x7f = 0x55 when FPGA programmed. */
@@ -887,7 +893,8 @@ static int snd_emu10k1_emu1010_init(struct snd_emu10k1 *emu)
 		dev_info(emu->card->dev,
 			 "emu1010: Loading Hana Firmware file failed, reg = 0x%x\n",
 			 reg);
-		return -ENODEV;
+		err = -ENODEV;
+		goto fail;
 	}
 
 	dev_info(emu->card->dev, "emu1010: Hana Firmware loaded\n");
@@ -947,7 +954,9 @@ static int snd_emu10k1_emu1010_init(struct snd_emu10k1 *emu)
 	// so it is safe to simply enable the outputs.
 	snd_emu1010_fpga_write(emu, EMU_HANA_UNMUTE, EMU_UNMUTE);
 
-	return 0;
+fail:
+	snd_emu1010_fpga_unlock(emu);
+	return err;
 }
 /*
  *  Create the EMU10K1 instance
@@ -969,9 +978,10 @@ static void snd_emu10k1_free(struct snd_card *card)
 	}
 	if (emu->card_capabilities->emu_model == EMU_MODEL_EMU1010) {
 		/* Disable 48Volt power to Audio Dock */
-		snd_emu1010_fpga_write(emu, EMU_HANA_DOCK_PWR, 0);
+		snd_emu1010_fpga_write_lock(emu, EMU_HANA_DOCK_PWR, 0);
 	}
 	cancel_work_sync(&emu->emu1010.work);
+	mutex_destroy(&emu->emu1010.lock);
 	release_firmware(emu->firmware);
 	release_firmware(emu->dock_fw);
 	snd_util_memhdr_free(emu->memhdr);
@@ -1551,6 +1561,7 @@ int snd_emu10k1_create(struct snd_card *card,
 	emu->synth = NULL;
 	emu->get_synth_voice = NULL;
 	INIT_WORK(&emu->emu1010.work, emu1010_work);
+	mutex_init(&emu->emu1010.lock);
 	/* read revision & serial */
 	emu->revision = pci->revision;
 	pci_read_config_dword(pci, PCI_SUBSYSTEM_VENDOR_ID, &emu->serial);