gpu: host1x: Add syncpoint wait and interrupts
Add support for sync point interrupts, and sync point wait. Sync
point wait used interrupts for unblocking wait.
Signed-off-by: Arto Merilainen <amerilainen@nvidia.com>
Signed-off-by: Terje Bergstrom <tbergstrom@nvidia.com>
Reviewed-by: Thierry Reding <thierry.reding@avionic-design.de>
Tested-by: Thierry Reding <thierry.reding@avionic-design.de>
Tested-by: Erik Faye-Lund <kusmabite@gmail.com>
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
diff --git a/drivers/gpu/host1x/syncpt.c b/drivers/gpu/host1x/syncpt.c
index 30385f6..07fad14 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 @@
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;