ALSA: firewire-lib: allocate DMA buffer separately

For correct cache coherency on some architectures, DMA buffers must be
allocated in a different cache line than data that is concurrently used
by the CPU.

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

sound/firewire/cmp.c

@@ -117,9 +117,12 @@ int cmp_connection_init(struct cmp_connection *c,
 	if (ipcr_index >= (impr & IMPR_PLUGS_MASK))
 		return -EINVAL;
 
+	err = fw_iso_resources_init(&c->resources, unit);
+	if (err < 0)
+		return err;
+
 	c->connected = false;
 	mutex_init(&c->mutex);
-	fw_iso_resources_init(&c->resources, unit);
 	c->last_pcr_value = cpu_to_be32(0x80000000);
 	c->pcr_index = ipcr_index;
 	c->max_speed = (impr & IMPR_SPEED_MASK) >> IMPR_SPEED_SHIFT;

sound/firewire/iso-resources.c

@@ -11,6 +11,7 @@
 #include <linux/jiffies.h>
 #include <linux/mutex.h>
 #include <linux/sched.h>
+#include <linux/slab.h>
 #include <linux/spinlock.h>
 #include "iso-resources.h"
 
@@ -22,12 +23,18 @@
  * If the device does not support all channel numbers, change @r->channels_mask
  * after calling this function.
  */
-void fw_iso_resources_init(struct fw_iso_resources *r, struct fw_unit *unit)
+int fw_iso_resources_init(struct fw_iso_resources *r, struct fw_unit *unit)
 {
+	r->buffer = kmalloc(2 * 4, GFP_KERNEL);
+	if (!r->buffer)
+		return -ENOMEM;
+
 	r->channels_mask = ~0uLL;
 	r->unit = fw_unit_get(unit);
 	mutex_init(&r->mutex);
 	r->allocated = false;
+
+	return 0;
 }
 
 /**
@@ -37,6 +44,7 @@ void fw_iso_resources_init(struct fw_iso_resources *r, struct fw_unit *unit)
 void fw_iso_resources_destroy(struct fw_iso_resources *r)
 {
 	WARN_ON(r->allocated);
+	kfree(r->buffer);
 	mutex_destroy(&r->mutex);
 	fw_unit_put(r->unit);
 }

sound/firewire/iso-resources.h

@@ -24,11 +24,11 @@ struct fw_iso_resources {
 	unsigned int bandwidth_overhead;
 	int generation; /* in which allocation is valid */
 	bool allocated;
-	__be32 buffer[2];
+	__be32 *buffer;
 };
 
-void fw_iso_resources_init(struct fw_iso_resources *r,
-			   struct fw_unit *unit);
+int fw_iso_resources_init(struct fw_iso_resources *r,
+			  struct fw_unit *unit);
 void fw_iso_resources_destroy(struct fw_iso_resources *r);
 
 int fw_iso_resources_allocate(struct fw_iso_resources *r,