diff options
Diffstat (limited to 'drivers/gpu/host1x/syncpt.c')
| -rw-r--r-- | drivers/gpu/host1x/syncpt.c | 159 |
1 files changed, 159 insertions, 0 deletions
diff --git a/drivers/gpu/host1x/syncpt.c b/drivers/gpu/host1x/syncpt.c index 30385f62dae..07fad1412ba 100644 --- a/drivers/gpu/host1x/syncpt.c +++ b/drivers/gpu/host1x/syncpt.c @@ -24,6 +24,10 @@ #include "syncpt.h" #include "dev.h" +#include "intr.h" + +#define SYNCPT_CHECK_PERIOD (2 * HZ) +#define MAX_STUCK_CHECK_COUNT 15 static struct host1x_syncpt *_host1x_syncpt_alloc(struct host1x *host, struct device *dev, @@ -141,6 +145,161 @@ void host1x_syncpt_incr(struct host1x_syncpt *sp) host1x_syncpt_cpu_incr(sp); } +/* + * Updated sync point form hardware, and returns true if syncpoint is expired, + * false if we may need to wait + */ +static bool syncpt_load_min_is_expired(struct host1x_syncpt *sp, u32 thresh) +{ + host1x_hw_syncpt_load(sp->host, sp); + return host1x_syncpt_is_expired(sp, thresh); +} + +/* + * Main entrypoint for syncpoint value waits. + */ +int host1x_syncpt_wait(struct host1x_syncpt *sp, u32 thresh, long timeout, + u32 *value) +{ + DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); + void *ref; + struct host1x_waitlist *waiter; + int err = 0, check_count = 0; + u32 val; + + if (value) + *value = 0; + + /* first check cache */ + if (host1x_syncpt_is_expired(sp, thresh)) { + if (value) + *value = host1x_syncpt_load(sp); + return 0; + } + + /* try to read from register */ + val = host1x_hw_syncpt_load(sp->host, sp); + if (host1x_syncpt_is_expired(sp, thresh)) { + if (value) + *value = val; + goto done; + } + + if (!timeout) { + err = -EAGAIN; + goto done; + } + + /* allocate a waiter */ + waiter = kzalloc(sizeof(*waiter), GFP_KERNEL); + if (!waiter) { + err = -ENOMEM; + goto done; + } + + /* schedule a wakeup when the syncpoint value is reached */ + err = host1x_intr_add_action(sp->host, sp->id, thresh, + HOST1X_INTR_ACTION_WAKEUP_INTERRUPTIBLE, + &wq, waiter, &ref); + if (err) + goto done; + + err = -EAGAIN; + /* Caller-specified timeout may be impractically low */ + if (timeout < 0) + timeout = LONG_MAX; + + /* wait for the syncpoint, or timeout, or signal */ + while (timeout) { + long check = min_t(long, SYNCPT_CHECK_PERIOD, timeout); + int remain = wait_event_interruptible_timeout(wq, + syncpt_load_min_is_expired(sp, thresh), + check); + if (remain > 0 || host1x_syncpt_is_expired(sp, thresh)) { + if (value) + *value = host1x_syncpt_load(sp); + err = 0; + break; + } + if (remain < 0) { + err = remain; + break; + } + timeout -= check; + if (timeout && check_count <= MAX_STUCK_CHECK_COUNT) { + dev_warn(sp->host->dev, + "%s: syncpoint id %d (%s) stuck waiting %d, timeout=%ld\n", + current->comm, sp->id, sp->name, + thresh, timeout); + check_count++; + } + } + host1x_intr_put_ref(sp->host, sp->id, ref); + +done: + return err; +} +EXPORT_SYMBOL(host1x_syncpt_wait); + +/* + * Returns true if syncpoint is expired, false if we may need to wait + */ +bool host1x_syncpt_is_expired(struct host1x_syncpt *sp, u32 thresh) +{ + u32 current_val; + u32 future_val; + smp_rmb(); + current_val = (u32)atomic_read(&sp->min_val); + future_val = (u32)atomic_read(&sp->max_val); + + /* Note the use of unsigned arithmetic here (mod 1<<32). + * + * c = current_val = min_val = the current value of the syncpoint. + * t = thresh = the value we are checking + * f = future_val = max_val = the value c will reach when all + * outstanding increments have completed. + * + * Note that c always chases f until it reaches f. + * + * Dtf = (f - t) + * Dtc = (c - t) + * + * Consider all cases: + * + * A) .....c..t..f..... Dtf < Dtc need to wait + * B) .....c.....f..t.. Dtf > Dtc expired + * C) ..t..c.....f..... Dtf > Dtc expired (Dct very large) + * + * Any case where f==c: always expired (for any t). Dtf == Dcf + * Any case where t==c: always expired (for any f). Dtf >= Dtc (because Dtc==0) + * Any case where t==f!=c: always wait. Dtf < Dtc (because Dtf==0, + * Dtc!=0) + * + * Other cases: + * + * A) .....t..f..c..... Dtf < Dtc need to wait + * A) .....f..c..t..... Dtf < Dtc need to wait + * A) .....f..t..c..... Dtf > Dtc expired + * + * So: + * Dtf >= Dtc implies EXPIRED (return true) + * Dtf < Dtc implies WAIT (return false) + * + * Note: If t is expired then we *cannot* wait on it. We would wait + * forever (hang the system). + * + * Note: do NOT get clever and remove the -thresh from both sides. It + * is NOT the same. + * + * If future valueis zero, we have a client managed sync point. In that + * case we do a direct comparison. + */ + if (!host1x_syncpt_client_managed(sp)) + return future_val - thresh >= current_val - thresh; + else + return (s32)(current_val - thresh) >= 0; +} + int host1x_syncpt_init(struct host1x *host) { struct host1x_syncpt *syncpt; |