gpu: nvgpu: retry tsg unbind if NEXT is set

The NEXT bit can remain set for the channel if timeslice expires before
scheduler clears it. Due to this nvgpu fails TSG unbind and in turn
nvrm_gpu fails channel close. In this case, checking the channel hw
state after some time can help see NEXT bit cleared by scheduler.

Reenable the tsg and return -EAGAIN to nvrm_gpu for it to retry again.

Bug 3144960
Bug 200520811

Change-Id: I35f417f02270e371a4e632986b73a00f8a4f921a
Signed-off-by: Sagar Kamble <skamble@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2468391
(cherry picked from commit cf287a4ef592e7329f813c076ec8bdad18dc5933)
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2479106
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>
Reviewed-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-by: svc-mobile-coverity <svc-mobile-coverity@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
GVS: Gerrit_Virtual_Submit

1 files changed, 7 insertions, 2 deletions

diff --git a/drivers/gpu/nvgpu/common/fifo/tsg.c b/drivers/gpu/nvgpu/common/fifo/tsg.c
index 841dd465..ebcdd2be 100644
--- a/drivers/gpu/nvgpu/common/fifo/tsg.c
+++ b/drivers/gpu/nvgpu/common/fifo/tsg.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014-2020, NVIDIA CORPORATION.  All rights reserved.
+ * Copyright (c) 2014-2021, NVIDIA CORPORATION.  All rights reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
@@ -148,7 +148,7 @@ int gk20a_tsg_bind_channel(struct tsg_gk20a *tsg,
 }
 
 /* The caller must ensure that channel belongs to a tsg */
-int gk20a_tsg_unbind_channel(struct channel_gk20a *ch)
+int gk20a_tsg_unbind_channel(struct channel_gk20a *ch, bool force)
 {
         struct gk20a *g = ch->g;
         struct tsg_gk20a *tsg = tsg_gk20a_from_ch(ch);
@@ -159,6 +159,11 @@ int gk20a_tsg_unbind_channel(struct channel_gk20a *ch)
         }
 
         err = gk20a_fifo_tsg_unbind_channel(ch);
+
+        if (!force && err == -EAGAIN) {
+                return err;
+        }
+
         if (err) {
                 nvgpu_err(g, "Channel %d unbind failed, tearing down TSG %d",
                         ch->chid, tsg->tsgid);