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mailbox: switch to hrtimer for tx_complete polling

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The mailbox core uses jiffy based timer to handle polling for the
transmit completion. If the client/protocol have/support notification
of the last packet transmit completion via ACK packet, then we tick the
Tx state machine immediately in the callback. However if the client
doesn't support that mechanism we might end-up waiting for atleast a
jiffy even though the remote is ready to receive the next request.

This patch switches the timer used for that polling from jiffy-based
to hrtimer-based so that we can support polling at much higher time
resolution.

Reported-and-suggested-by: Juri Lelli <[email protected]>
Signed-off-by: Sudeep Holla <[email protected]>
Signed-off-by: Jassi Brar <[email protected]>
This commit is contained in:
Sudeep Holla 2015-07-31 11:48:05 +01:00 • committed by Jassi Brar
commit 0cc67945ea
2 changed files with 19 additions and 15 deletions
Download patch file Download diff file Expand all files Collapse all files

27
drivers/mailbox/mailbox.c
View file

@ -26,8 +26,6 @@
static LIST_HEAD(mbox_cons);
static DEFINE_MUTEX(con_mutex);
static void poll_txdone(unsigned long data);
static int add_to_rbuf(struct mbox_chan *chan, void *mssg)
{
int idx;
@ -88,7 +86,9 @@ exit:
spin_unlock_irqrestore(&chan->lock, flags);
if (!err && (chan->txdone_method & TXDONE_BY_POLL))
poll_txdone((unsigned long)chan->mbox);
/* kick start the timer immediately to avoid delays */
hrtimer_start(&chan->mbox->poll_hrt, ktime_set(0, 0),
HRTIMER_MODE_REL);
}
static void tx_tick(struct mbox_chan *chan, int r)
@ -112,9 +112,10 @@ static void tx_tick(struct mbox_chan *chan, int r)
complete(&chan->tx_complete);
}
static void poll_txdone(unsigned long data)
static enum hrtimer_restart txdone_hrtimer(struct hrtimer *hrtimer)
{
struct mbox_controller *mbox = (struct mbox_controller *)data;
struct mbox_controller *mbox =
container_of(hrtimer, struct mbox_controller, poll_hrt);
bool txdone, resched = false;
int i;
@ -130,9 +131,11 @@ static void poll_txdone(unsigned long data)
}
}
if (resched)
mod_timer(&mbox->poll, jiffies +
msecs_to_jiffies(mbox->txpoll_period));
if (resched) {
hrtimer_forward_now(hrtimer, ms_to_ktime(mbox->txpoll_period));
return HRTIMER_RESTART;
}
return HRTIMER_NORESTART;
}
/**
@ -451,9 +454,9 @@ int mbox_controller_register(struct mbox_controller *mbox)
txdone = TXDONE_BY_ACK;
if (txdone == TXDONE_BY_POLL) {
mbox->poll.function = &poll_txdone;
mbox->poll.data = (unsigned long)mbox;
init_timer(&mbox->poll);
hrtimer_init(&mbox->poll_hrt, CLOCK_MONOTONIC,
HRTIMER_MODE_REL);
mbox->poll_hrt.function = txdone_hrtimer;
}
for (i = 0; i < mbox->num_chans; i++) {
@ -495,7 +498,7 @@ void mbox_controller_unregister(struct mbox_controller *mbox)
mbox_free_channel(&mbox->chans[i]);
if (mbox->txdone_poll)
del_timer_sync(&mbox->poll);
hrtimer_cancel(&mbox->poll_hrt);
mutex_unlock(&con_mutex);
}