gpu: nvgpu: don't re-enable TSG if timed out

In gk20a_fifo_tsg_unbind_channel(), we disable/preempt TSG, unbind one channel
from TSG, and then re-enable rest of the channels in TSG

But it is possible that TSG has already timed out due to some error and is
already disabled
If we re-enable all channels in such case, it can cause random issues right
after re-enabling faulted channel

Hence do not re-enable TSG if it has timedout

Since we disable all channels of TSG if one channel encounters fatal error,
it is safe to assume that TSG has timed out if one channel has timed out

Bug 1958308
Bug 200327095

Change-Id: I958ca6a2b408ff1338f2e551a79c072f1e203eda
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1585421
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

1 files changed, 16 insertions, 2 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/fifo_gk20a.c b/drivers/gpu/nvgpu/gk20a/fifo_gk20a.c
index 3b7dce32..194824c3 100644
--- a/drivers/gpu/nvgpu/gk20a/fifo_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/fifo_gk20a.c
@@ -1952,6 +1952,12 @@ int gk20a_fifo_tsg_unbind_channel(struct channel_gk20a *ch)
         struct fifo_gk20a *f = &g->fifo;
         struct tsg_gk20a *tsg = &f->tsg[ch->tsgid];
         int err;
+        bool tsg_timedout = false;
+
+        /* If one channel in TSG times out, we disable all channels */
+        nvgpu_rwsem_down_write(&tsg->ch_list_lock);
+        tsg_timedout = ch->has_timedout;
+        nvgpu_rwsem_up_write(&tsg->ch_list_lock);
 
         /* Disable TSG and examine status before unbinding channel */
         g->ops.fifo.disable_tsg(tsg);
@@ -1976,14 +1982,22 @@ int gk20a_fifo_tsg_unbind_channel(struct channel_gk20a *ch)
         nvgpu_list_del(&ch->ch_entry);
         nvgpu_rwsem_up_write(&tsg->ch_list_lock);
 
-        g->ops.fifo.enable_tsg(tsg);
+        /*
+         * Don't re-enable all channels if TSG has timed out already
+         *
+         * Note that we can skip disabling and preempting TSG too in case of
+         * time out, but we keep that to ensure TSG is kicked out
+         */
+        if (!tsg_timedout)
+                g->ops.fifo.enable_tsg(tsg);
 
         gk20a_channel_abort_clean_up(ch);
 
         return 0;
 
 fail_enable_tsg:
-        g->ops.fifo.enable_tsg(tsg);
+        if (!tsg_timedout)
+                g->ops.fifo.enable_tsg(tsg);
         return err;
 }