media: rc: make raw event fifo size a module parameter

[Heiner Kallweit <hkallweit1@gmail.com>]

Currently the fifo size is 512 elements. After a recent patch the size
of struct ir_raw_event is down to 8 bytes, so the fifo still consumes
4KB. In most cases a much smaller fifo is sufficient, e.g. nuvoton-cir
triggers event processing after 24 events latest. However the needed
fifo size may also depend on system performance.

Therefore make the fifo size a module parameter with the current value
of 512 being the default.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
 drivers/media/rc/rc-core-priv.h |  2 +-
 drivers/media/rc/rc-ir-raw.c    | 20 +++++++++++++++++---
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/media/rc/rc-core-priv.h b/drivers/media/rc/rc-core-priv.h
index 585d5e5..ae6f81e 100644
--- a/drivers/media/rc/rc-core-priv.h
+++ b/drivers/media/rc/rc-core-priv.h
@@ -39,7 +39,7 @@ struct ir_raw_event_ctrl {
 	struct task_struct		*thread;
 	spinlock_t			lock;
 	/* fifo for the pulse/space durations */
-	DECLARE_KFIFO(kfifo, struct ir_raw_event, MAX_IR_EVENT_SIZE);
+	DECLARE_KFIFO_PTR(kfifo, struct ir_raw_event);
 	ktime_t				last_event;	/* when last event occurred */
 	enum raw_event_type		last_type;	/* last event type */
 	struct rc_dev			*dev;		/* pointer to the parent rc_dev */
diff --git a/drivers/media/rc/rc-ir-raw.c b/drivers/media/rc/rc-ir-raw.c
index 144304c..620b036 100644
--- a/drivers/media/rc/rc-ir-raw.c
+++ b/drivers/media/rc/rc-ir-raw.c
@@ -18,6 +18,7 @@
 #include <linux/kmod.h>
 #include <linux/sched.h>
 #include <linux/freezer.h>
+#include <linux/module.h>
 #include "rc-core-priv.h"
 
 /* Used to keep track of IR raw clients, protected by ir_raw_handler_lock */
@@ -28,6 +29,9 @@ static DEFINE_MUTEX(ir_raw_handler_lock);
 static LIST_HEAD(ir_raw_handler_list);
 static u64 available_protocols;
 
+/* module param */
+static unsigned int ir_raw_event_fifo_size = MAX_IR_EVENT_SIZE;
+
 static int ir_raw_event_thread(void *data)
 {
 	struct ir_raw_event ev;
@@ -262,7 +266,7 @@ int ir_raw_event_register(struct rc_dev *dev)
 	int rc;
 	struct ir_raw_handler *handler;
 
-	if (!dev)
+	if (!dev || !ir_raw_event_fifo_size)
 		return -EINVAL;
 
 	dev->raw = kzalloc(sizeof(*dev->raw), GFP_KERNEL);
@@ -271,7 +275,10 @@ int ir_raw_event_register(struct rc_dev *dev)
 
 	dev->raw->dev = dev;
 	dev->change_protocol = change_protocol;
-	INIT_KFIFO(dev->raw->kfifo);
+
+	rc = kfifo_alloc(&dev->raw->kfifo, ir_raw_event_fifo_size, GFP_KERNEL);
+	if (rc)
+		goto out;
 
 	spin_lock_init(&dev->raw->lock);
 	dev->raw->thread = kthread_run(ir_raw_event_thread, dev->raw,
@@ -279,7 +286,7 @@ int ir_raw_event_register(struct rc_dev *dev)
 
 	if (IS_ERR(dev->raw->thread)) {
 		rc = PTR_ERR(dev->raw->thread);
-		goto out;
+		goto out_kfifo;
 	}
 
 	mutex_lock(&ir_raw_handler_lock);
@@ -291,6 +298,8 @@ int ir_raw_event_register(struct rc_dev *dev)
 
 	return 0;
 
+out_kfifo:
+	kfifo_free(&dev->raw->kfifo);
 out:
 	kfree(dev->raw);
 	dev->raw = NULL;
@@ -313,6 +322,7 @@ void ir_raw_event_unregister(struct rc_dev *dev)
 			handler->raw_unregister(dev);
 	mutex_unlock(&ir_raw_handler_lock);
 
+	kfifo_free(&dev->raw->kfifo);
 	kfree(dev->raw);
 	dev->raw = NULL;
 }
@@ -353,3 +363,7 @@ void ir_raw_handler_unregister(struct ir_raw_handler *ir_raw_handler)
 	mutex_unlock(&ir_raw_handler_lock);
 }
 EXPORT_SYMBOL(ir_raw_handler_unregister);
+
+module_param_named(fifo_size, ir_raw_event_fifo_size, uint, S_IRUGO);
+MODULE_PARM_DESC(fifo_size,
+	"raw event fifo size, will be rounded up to next power of 2");
-- 
2.7.3