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