The kernel FIFO queue has a couple issues. The biggest issue is that
it causes extra latency in a path that can be used in real-time tasks,
such as communication with real-time remote processors.
The whole FIFO idea itself looks to be a leftover from before the
unified mailbox framework. The current mailbox framework expects
mbox_chan_received_data() to be called with data immediately as it
arrives. Remove the FIFO and pass the messages to the mailbox
framework directly as part of a threaded IRQ handler.
Signed-off-by: Andrew Davis <afd@xxxxxx>
---
drivers/mailbox/Kconfig | 9 ---
drivers/mailbox/omap-mailbox.c | 107 ++-------------------------------
2 files changed, 5 insertions(+), 111 deletions(-)
diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
index 42940108a1874..78e4c74fbe5c2 100644
--- a/drivers/mailbox/Kconfig
+++ b/drivers/mailbox/Kconfig
@@ -68,15 +68,6 @@ config OMAP2PLUS_MBOX
OMAP2/3; or IPU, IVA HD and DSP in OMAP4/5. Say Y here if you
want to use OMAP2+ Mailbox framework support.
-config OMAP_MBOX_KFIFO_SIZE
- int "Mailbox kfifo default buffer size (bytes)"
- depends on OMAP2PLUS_MBOX
- default 256
- help
- Specify the default size of mailbox's kfifo buffers (bytes).
- This can also be changed at runtime (via the mbox_kfifo_size
- module parameter).
-
config ROCKCHIP_MBOX
bool "Rockchip Soc Integrated Mailbox Support"
depends on ARCH_ROCKCHIP || COMPILE_TEST
diff --git a/drivers/mailbox/omap-mailbox.c b/drivers/mailbox/omap-mailbox.c
index c5d4083125856..46747559b438f 100644
--- a/drivers/mailbox/omap-mailbox.c
+++ b/drivers/mailbox/omap-mailbox.c
@@ -65,14 +65,6 @@ struct omap_mbox_fifo {
u32 intr_bit;
};
-struct omap_mbox_queue {
- spinlock_t lock;
- struct kfifo fifo;
- struct work_struct work;
- struct omap_mbox *mbox;
- bool full;
-};
-
struct omap_mbox_match_data {
u32 intr_type;
};
@@ -90,7 +82,6 @@ struct omap_mbox_device {
struct omap_mbox {
const char *name;
int irq;
- struct omap_mbox_queue *rxq;
struct omap_mbox_device *parent;
struct omap_mbox_fifo tx_fifo;
struct omap_mbox_fifo rx_fifo;
@@ -99,10 +90,6 @@ struct omap_mbox {
bool send_no_irq;
};
-static unsigned int mbox_kfifo_size = CONFIG_OMAP_MBOX_KFIFO_SIZE;
-module_param(mbox_kfifo_size, uint, S_IRUGO);
-MODULE_PARM_DESC(mbox_kfifo_size, "Size of omap's mailbox kfifo (bytes)");
-
static inline
unsigned int mbox_read_reg(struct omap_mbox_device *mdev, size_t ofs)
{
@@ -202,30 +189,6 @@ static void omap_mbox_disable_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
mbox_write_reg(mbox->parent, bit, irqdisable);
}
-/*
- * Message receiver(workqueue)
- */
-static void mbox_rx_work(struct work_struct *work)
-{
- struct omap_mbox_queue *mq =
- container_of(work, struct omap_mbox_queue, work);
- u32 msg;
- int len;
-
- while (kfifo_len(&mq->fifo) >= sizeof(msg)) {
- len = kfifo_out(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
- WARN_ON(len != sizeof(msg));
-
- mbox_chan_received_data(mq->mbox->chan, (void *)(uintptr_t)msg);
- spin_lock_irq(&mq->lock);
- if (mq->full) {
- mq->full = false;
- omap_mbox_enable_irq(mq->mbox, IRQ_RX);
- }
- spin_unlock_irq(&mq->lock);
- }
-}
-
/*
* Mailbox interrupt handler
*/
@@ -238,27 +201,15 @@ static void __mbox_tx_interrupt(struct omap_mbox *mbox)
static void __mbox_rx_interrupt(struct omap_mbox *mbox)
{
- struct omap_mbox_queue *mq = mbox->rxq;
u32 msg;
- int len;
while (!mbox_fifo_empty(mbox)) {
- if (unlikely(kfifo_avail(&mq->fifo) < sizeof(msg))) {
- omap_mbox_disable_irq(mbox, IRQ_RX);
- mq->full = true;
- goto nomem;
- }
-
msg = mbox_fifo_read(mbox);
-
- len = kfifo_in(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
- WARN_ON(len != sizeof(msg));
+ mbox_chan_received_data(mbox->chan, (void *)(uintptr_t)msg);
}
- /* no more messages in the fifo. clear IRQ source. */
+ /* clear IRQ source. */
ack_mbox_irq(mbox, IRQ_RX);
-nomem:
- schedule_work(&mbox->rxq->work);
}
static irqreturn_t mbox_interrupt(int irq, void *p)
@@ -274,57 +225,15 @@ static irqreturn_t mbox_interrupt(int irq, void *p)
return IRQ_HANDLED;
}
-static struct omap_mbox_queue *mbox_queue_alloc(struct omap_mbox *mbox,
- void (*work)(struct work_struct *))
-{
- struct omap_mbox_queue *mq;
- unsigned int size;
-
- if (!work)
- return NULL;
-
- mq = kzalloc(sizeof(*mq), GFP_KERNEL);
- if (!mq)
- return NULL;
-
- spin_lock_init(&mq->lock);
-
- /* kfifo size sanity check: alignment and minimal size */
- size = ALIGN(mbox_kfifo_size, sizeof(u32));
- size = max_t(unsigned int, size, sizeof(u32));
- if (kfifo_alloc(&mq->fifo, size, GFP_KERNEL))
- goto error;
-
- INIT_WORK(&mq->work, work);
- return mq;
-
-error:
- kfree(mq);
- return NULL;
-}
-
-static void mbox_queue_free(struct omap_mbox_queue *q)
-{
- kfifo_free(&q->fifo);
- kfree(q);
-}
-
static int omap_mbox_startup(struct omap_mbox *mbox)
{
int ret = 0;
- struct omap_mbox_queue *mq;
-
- mq = mbox_queue_alloc(mbox, mbox_rx_work);
- if (!mq)
- return -ENOMEM;
- mbox->rxq = mq;
- mq->mbox = mbox;
- ret = request_irq(mbox->irq, mbox_interrupt, IRQF_SHARED,
- mbox->name, mbox);
+ ret = request_threaded_irq(mbox->irq, NULL, mbox_interrupt,
+ IRQF_ONESHOT, mbox->name, mbox);
if (unlikely(ret)) {
pr_err("failed to register mailbox interrupt:%d\n", ret);
- goto fail_request_irq;
+ return ret;
}
if (mbox->send_no_irq)
@@ -333,18 +242,12 @@ static int omap_mbox_startup(struct omap_mbox *mbox)
omap_mbox_enable_irq(mbox, IRQ_RX);
return 0;
-
-fail_request_irq:
- mbox_queue_free(mbox->rxq);
- return ret;
}
static void omap_mbox_fini(struct omap_mbox *mbox)
{
omap_mbox_disable_irq(mbox, IRQ_RX);
free_irq(mbox->irq, mbox);
- flush_work(&mbox->rxq->work);
- mbox_queue_free(mbox->rxq);
}
static int omap_mbox_chan_startup(struct mbox_chan *chan)
--
2.39.2
