ALSA: mpu401: clean up interrupt specification

The semantics of snd_mpu401_uart_new()'s interrupt parameters are
somewhat counterintuitive:  To prevent the function from allocating its
own interrupt, either the irq number must be invalid, or the irq_flags
parameter must be zero.  At the same time, the irq parameter being
invalid specifies that the mpu401 code has to work without an interrupt
allocated by the caller.  This implies that, if there is an interrupt
and it is allocated by the caller, the irq parameter must be set to
a valid-looking number which then isn't actually used.

With the removal of IRQF_DISABLED, zero becomes a valid irq_flags value,
which forces us to handle the parameters differently.

This patch introduces a new flag MPU401_INFO_IRQ_HOOK for when the
device interrupt is handled by the caller, and makes the allocation of
the interrupt to depend only on the irq parameter.  As suggested by
Takashi, the irq_flags parameter was dropped because, when used, it had
the constant value IRQF_DISABLED.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

2 files changed, 11 insertions, 12 deletions

diff --git a/sound/drivers/mpu401/mpu401.c b/sound/drivers/mpu401/mpu401.c
index 149d05a8202..1c02852acee 100644
--- a/sound/drivers/mpu401/mpu401.c
+++ b/sound/drivers/mpu401/mpu401.c
@@ -86,8 +86,7 @@ static int snd_mpu401_create(int dev, struct snd_card **rcard)
 	}
 
 	err = snd_mpu401_uart_new(card, 0, MPU401_HW_MPU401, port[dev], 0,
-				  irq[dev], irq[dev] >= 0 ? IRQF_DISABLED : 0,
-				  NULL);
+				  irq[dev], NULL);
 	if (err < 0) {
 		printk(KERN_ERR "MPU401 not detected at 0x%lx\n", port[dev]);
 		goto _err;
diff --git a/sound/drivers/mpu401/mpu401_uart.c b/sound/drivers/mpu401/mpu401_uart.c
index 2af09996a3d..9d01c181fec 100644
--- a/sound/drivers/mpu401/mpu401_uart.c
+++ b/sound/drivers/mpu401/mpu401_uart.c
@@ -3,7 +3,7 @@
  *  Routines for control of MPU-401 in UART mode
  *
  *  MPU-401 supports UART mode which is not capable generate transmit
- *  interrupts thus output is done via polling. Also, if irq < 0, then
+ *  interrupts thus output is done via polling. Without interrupt,
  *  input is done also via polling. Do not expect good performance.
  *
  *
@@ -374,7 +374,7 @@ snd_mpu401_uart_input_trigger(struct snd_rawmidi_substream *substream, int up)
 			/* first time - flush FIFO */
 			while (max-- > 0)
 				mpu->read(mpu, MPU401D(mpu));
-			if (mpu->irq < 0)
+			if (mpu->info_flags & MPU401_INFO_USE_TIMER)
 				snd_mpu401_uart_add_timer(mpu, 1);
 		}
 		
@@ -383,7 +383,7 @@ snd_mpu401_uart_input_trigger(struct snd_rawmidi_substream *substream, int up)
 		snd_mpu401_uart_input_read(mpu);
 		spin_unlock_irqrestore(&mpu->input_lock, flags);
 	} else {
-		if (mpu->irq < 0)
+		if (mpu->info_flags & MPU401_INFO_USE_TIMER)
 			snd_mpu401_uart_remove_timer(mpu, 1);
 		clear_bit(MPU401_MODE_BIT_INPUT_TRIGGER, &mpu->mode);
 	}
@@ -496,7 +496,7 @@ static struct snd_rawmidi_ops snd_mpu401_uart_input =
 static void snd_mpu401_uart_free(struct snd_rawmidi *rmidi)
 {
 	struct snd_mpu401 *mpu = rmidi->private_data;
-	if (mpu->irq_flags && mpu->irq >= 0)
+	if (mpu->irq >= 0)
 		free_irq(mpu->irq, (void *) mpu);
 	release_and_free_resource(mpu->res);
 	kfree(mpu);
@@ -509,8 +509,7 @@ static void snd_mpu401_uart_free(struct snd_rawmidi *rmidi)
  * @hardware: the hardware type, MPU401_HW_XXXX
  * @port: the base address of MPU401 port
  * @info_flags: bitflags MPU401_INFO_XXX
- * @irq: the irq number, -1 if no interrupt for mpu
- * @irq_flags: the irq request flags (SA_XXX), 0 if irq was already reserved.
+ * @irq: the ISA irq number, -1 if not to be allocated
  * @rrawmidi: the pointer to store the new rawmidi instance
  *
  * Creates a new MPU-401 instance.
@@ -525,7 +524,7 @@ int snd_mpu401_uart_new(struct snd_card *card, int device,
 			unsigned short hardware,
 			unsigned long port,
 			unsigned int info_flags,
-			int irq, int irq_flags,
+			int irq,
 			struct snd_rawmidi ** rrawmidi)
 {
 	struct snd_mpu401 *mpu;
@@ -577,8 +576,8 @@ int snd_mpu401_uart_new(struct snd_card *card, int device,
 		mpu->cport = port + 2;
 	else
 		mpu->cport = port + 1;
-	if (irq >= 0 && irq_flags) {
-		if (request_irq(irq, snd_mpu401_uart_interrupt, irq_flags,
+	if (irq >= 0) {
+		if (request_irq(irq, snd_mpu401_uart_interrupt, IRQF_DISABLED,
 				"MPU401 UART", (void *) mpu)) {
 			snd_printk(KERN_ERR "mpu401_uart: "
 				   "unable to grab IRQ %d\n", irq);
@@ -586,9 +585,10 @@ int snd_mpu401_uart_new(struct snd_card *card, int device,
 			return -EBUSY;
 		}
 	}
+	if (irq < 0 && !(info_flags & MPU401_INFO_IRQ_HOOK))
+		info_flags |= MPU401_INFO_USE_TIMER;
 	mpu->info_flags = info_flags;
 	mpu->irq = irq;
-	mpu->irq_flags = irq_flags;
 	if (card->shortname[0])
 		snprintf(rmidi->name, sizeof(rmidi->name), "%s MIDI",
 			 card->shortname);