gpu: nvgpu: Misc fixes for crashes on shutdown

Fix miscellaneous issues seen during driver shutdown.

 o  Make sure pointers are valid before accessing them.
 o  Busy the GPU during channel timeout.
 o  Cancel delayed work on channels.
 o  Avoid access to channels that may have been freed.

Bug 1816516
Bug 1807277

Change-Id: I62df40373fdfb1c4a011364e8c435176a08a7a96
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Reviewed-on: http://git-master/r/1250026
(cherry picked from commit 64a95fc96c8ef7c5af9c53c4bb3402626e0d2f60)
Reviewed-on: http://git-master/r/1274474
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/mm_gk20a.c b/drivers/gpu/nvgpu/gk20a/mm_gk20a.c
index 792fa098..2e338fef 100644
--- a/drivers/gpu/nvgpu/gk20a/mm_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/mm_gk20a.c
@@ -219,6 +219,11 @@ static inline void pramin_access_batch_rd_n(struct gk20a *g, u32 start,
 {
         u32 r = start, *dest_u32 = *arg;
 
+        if (!g->regs) {
+                __gk20a_warn_on_no_regs();
+                return;
+        }
+
         while (words--) {
                 *dest_u32++ = gk20a_readl(g, r);
                 r += sizeof(u32);
@@ -232,6 +237,11 @@ static inline void pramin_access_batch_wr_n(struct gk20a *g, u32 start,
 {
         u32 r = start, *src_u32 = *arg;
 
+        if (!g->regs) {
+                __gk20a_warn_on_no_regs();
+                return;
+        }
+
         while (words--) {
                 writel_relaxed(*src_u32++, g->regs + r);
                 r += sizeof(u32);
@@ -245,6 +255,11 @@ static inline void pramin_access_batch_set(struct gk20a *g, u32 start,
 {
         u32 r = start, repeat = **arg;
 
+        if (!g->regs) {
+                __gk20a_warn_on_no_regs();
+                return;
+        }
+
         while (words--) {
                 writel_relaxed(repeat, g->regs + r);
                 r += sizeof(u32);