gpu: nvgpu: add NVGPU_IOCTL_CHANNEL_RESCHEDULE_RUNLIST

Add NVGPU_IOCTL_CHANNEL_RESCHEDULE_RUNLIST ioctl to reschedule runlist,
and optionally check host and FECS status to preempt pending load of
context not belonging to the calling channel on GR engine during context
switch.
This should be called immediately after a submit to decrease worst case
submit to start latency for high interleave channel.
There is less than 0.002% chance that the ioctl blocks up to couple
miliseconds due to race condition of FECS status changing while being read.
For GV11B it will always preempt pending load of unwanted context since
there is no chance that ioctl blocks due to race condition.
Also fix bug with host reschedule for multiple runlists which needs to
write both runlist registers.

Bug 1987640
Bug 1924808
Change-Id: I0b7e2f91bd18b0b20928e5a3311b9426b1bf1848
Signed-off-by: David Li <davli@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1549050
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

1 files changed, 89 insertions, 21 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/fifo_gk20a.c b/drivers/gpu/nvgpu/gk20a/fifo_gk20a.c
index 22dc1d60..c94fc536 100644
--- a/drivers/gpu/nvgpu/gk20a/fifo_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/fifo_gk20a.c
@@ -53,6 +53,7 @@
 #include <nvgpu/hw/gk20a/hw_gr_gk20a.h>
 
 #define FECS_METHOD_WFI_RESTORE 0x80000
+#define FECS_MAILBOX_0_ACK_RESTORE 0x4
 
 static int gk20a_fifo_update_runlist_locked(struct gk20a *g, u32 runlist_id,
                                             u32 chid, bool add,
@@ -3282,7 +3283,6 @@ static int gk20a_fifo_update_runlist_locked(struct gk20a *g, u32 runlist_id,
         u32 new_buf;
         struct channel_gk20a *ch = NULL;
         struct tsg_gk20a *tsg = NULL;
-        u32 count = 0;
         u32 runlist_entry_words = f->runlist_entry_size / sizeof(u32);
 
         runlist = &f->runlist_info[runlist_id];
@@ -3345,12 +3345,13 @@ static int gk20a_fifo_update_runlist_locked(struct gk20a *g, u32 runlist_id,
                         ret = -E2BIG;
                         goto clean_up;
                 }
-                count = (runlist_end - runlist_entry_base) / runlist_entry_words;
-                WARN_ON(count > f->num_runlist_entries);
+                runlist->count = (runlist_end - runlist_entry_base) /
+                        runlist_entry_words;
+                WARN_ON(runlist->count > f->num_runlist_entries);
         } else  /* suspend to remove all channels */
-                count = 0;
+                runlist->count = 0;
 
-        g->ops.fifo.runlist_hw_submit(g, runlist_id, count, new_buf);
+        g->ops.fifo.runlist_hw_submit(g, runlist_id, runlist->count, new_buf);
 
         if (wait_for_finish) {
                 ret = g->ops.fifo.runlist_wait_pending(g, runlist_id);
@@ -3406,31 +3407,98 @@ end:
         return ret;
 }
 
+/* trigger host preempt of GR pending load ctx if that ctx is not for ch */
+static int __locked_fifo_reschedule_preempt_next(struct channel_gk20a *ch,
+                bool wait_preempt)
+{
+        struct gk20a *g = ch->g;
+        struct fifo_runlist_info_gk20a *runlist =
+                &g->fifo.runlist_info[ch->runlist_id];
+        int ret = 0;
+        u32 gr_eng_id = 0;
+        u32 engstat = 0, ctxstat = 0, fecsstat0 = 0, fecsstat1 = 0;
+        s32 preempt_id = -1;
+        u32 preempt_type = 0;
+
+        if (1 != gk20a_fifo_get_engine_ids(
+                g, &gr_eng_id, 1, ENGINE_GR_GK20A))
+                return ret;
+        if (!(runlist->eng_bitmask & (1 << gr_eng_id)))
+                return ret;
+
+        if (wait_preempt && gk20a_readl(g, fifo_preempt_r()) &
+                fifo_preempt_pending_true_f())
+                return ret;
+
+        fecsstat0 = gk20a_readl(g, gr_fecs_ctxsw_mailbox_r(0));
+        engstat = gk20a_readl(g, fifo_engine_status_r(gr_eng_id));
+        ctxstat = fifo_engine_status_ctx_status_v(engstat);
+        if (ctxstat == fifo_engine_status_ctx_status_ctxsw_switch_v()) {
+                /* host switching to next context, preempt that if needed */
+                preempt_id = fifo_engine_status_next_id_v(engstat);
+                preempt_type = fifo_engine_status_next_id_type_v(engstat);
+        } else
+                return ret;
+        if (preempt_id == ch->tsgid && preempt_type)
+                return ret;
+        fecsstat1 = gk20a_readl(g, gr_fecs_ctxsw_mailbox_r(0));
+        if (fecsstat0 != FECS_MAILBOX_0_ACK_RESTORE ||
+                fecsstat1 != FECS_MAILBOX_0_ACK_RESTORE) {
+                /* preempt useless if FECS acked save and started restore */
+                return ret;
+        }
+
+        gk20a_fifo_issue_preempt(g, preempt_id, preempt_type);
+#ifdef TRACEPOINTS_ENABLED
+        trace_gk20a_reschedule_preempt_next(ch->chid, fecsstat0, engstat,
+                fecsstat1, gk20a_readl(g, gr_fecs_ctxsw_mailbox_r(0)),
+                gk20a_readl(g, fifo_preempt_r()));
+#endif
+        if (wait_preempt) {
+                g->ops.fifo.is_preempt_pending(
+                        g, preempt_id, preempt_type, PREEMPT_TIMEOUT_RC);
+        }
+#ifdef TRACEPOINTS_ENABLED
+        trace_gk20a_reschedule_preempted_next(ch->chid);
+#endif
+        return ret;
+}
+
+int gk20a_fifo_reschedule_runlist(struct channel_gk20a *ch, bool preempt_next)
+{
+        return nvgpu_fifo_reschedule_runlist(ch, preempt_next, true);
+}
+
 /* trigger host to expire current timeslice and reschedule runlist from front */
-int gk20a_fifo_reschedule_runlist(struct gk20a *g, u32 runlist_id)
+int nvgpu_fifo_reschedule_runlist(struct channel_gk20a *ch, bool preempt_next,
+                bool wait_preempt)
 {
+        struct gk20a *g = ch->g;
         struct fifo_runlist_info_gk20a *runlist;
         u32 token = PMU_INVALID_MUTEX_OWNER_ID;
         u32 mutex_ret;
         int ret = 0;
 
-        runlist = &g->fifo.runlist_info[runlist_id];
-        if (nvgpu_mutex_tryacquire(&runlist->runlist_lock)) {
-                mutex_ret = nvgpu_pmu_mutex_acquire(
-                        &g->pmu, PMU_MUTEX_ID_FIFO, &token);
+        runlist = &g->fifo.runlist_info[ch->runlist_id];
+        if (!nvgpu_mutex_tryacquire(&runlist->runlist_lock))
+                return -EBUSY;
 
-                gk20a_writel(g, fifo_runlist_r(),
-                        gk20a_readl(g, fifo_runlist_r()));
-                gk20a_fifo_runlist_wait_pending(g, runlist_id);
+        mutex_ret = nvgpu_pmu_mutex_acquire(
+                &g->pmu, PMU_MUTEX_ID_FIFO, &token);
+
+        g->ops.fifo.runlist_hw_submit(
+                g, ch->runlist_id, runlist->count, runlist->cur_buffer);
+
+        if (preempt_next)
+                __locked_fifo_reschedule_preempt_next(ch, wait_preempt);
+
+        gk20a_fifo_runlist_wait_pending(g, ch->runlist_id);
+
+        if (!mutex_ret)
+                nvgpu_pmu_mutex_release(
+                        &g->pmu, PMU_MUTEX_ID_FIFO, &token);
+        nvgpu_mutex_release(&runlist->runlist_lock);
 
-                if (!mutex_ret)
-                        nvgpu_pmu_mutex_release(
-                                &g->pmu, PMU_MUTEX_ID_FIFO, &token);
-                nvgpu_mutex_release(&runlist->runlist_lock);
-        } else {
-                /* someone else is writing fifo_runlist_r so not needed here */
-                ret = -EBUSY;
-        }
         return ret;
 }