1 files changed, 30 insertions, 2 deletions

diff --git a/drivers/gpu/nvgpu/os/linux/ioctl_ctrl.c b/drivers/gpu/nvgpu/os/linux/ioctl_ctrl.c
index 6fa15421..271c5d92 100644
--- a/drivers/gpu/nvgpu/os/linux/ioctl_ctrl.c
+++ b/drivers/gpu/nvgpu/os/linux/ioctl_ctrl.c
@@ -19,6 +19,7 @@
 #include <linux/file.h>
 #include <linux/anon_inodes.h>
 #include <linux/fs.h>
+#include <linux/pm_runtime.h>
 #include <uapi/linux/nvgpu.h>
 
 #include <nvgpu/bitops.h>
@@ -596,19 +597,46 @@ static int gk20a_ctrl_get_fbp_l2_masks(
 static int nvgpu_gpu_ioctl_l2_fb_ops(struct gk20a *g,
                 struct nvgpu_gpu_l2_fb_args *args)
 {
-        int err = 0;
+        int ret;
+        bool always_poweron;
 
         if ((!args->l2_flush && !args->fb_flush) ||
             (!args->l2_flush && args->l2_invalidate))
                 return -EINVAL;
 
+        /* Handle this case for joint rails or DGPU */
+        always_poweron = (!nvgpu_is_enabled(g, NVGPU_CAN_RAILGATE) ||
+                                !pm_runtime_enabled(dev_from_gk20a(g)));
+
+        /* In case of not always power_on, exit if g->power_on is false */
+        if (!always_poweron && !gk20a_check_poweron(g)) {
+                return 0;
+        }
+
+        /* There is a small window between a call to gk20a_idle() has occured
+         * and railgate being actually triggered(setting g->power_on = false),
+         * when l2_flush can race with railgate. Its better to take a busy_lock
+         * to prevent the gk20a_idle() from proceeding. There is a very small
+         * chance that gk20a_idle() might begin before gk20a_busy(). Having
+         * a locked access to g->power_on further reduces the probability of
+         * gk20a_idle() being triggered before gk20a_busy()
+         */
+        ret = gk20a_busy(g);
+
+        if (ret != 0) {
+                nvgpu_err(g, "failed to take power ref");
+                return ret;
+        }
+
         if (args->l2_flush)
                 g->ops.mm.l2_flush(g, args->l2_invalidate ? true : false);
 
         if (args->fb_flush)
                 g->ops.mm.fb_flush(g);
 
-        return err;
+        gk20a_idle(g);
+
+        return 0;
 }
 
 static int nvgpu_gpu_ioctl_set_mmu_debug_mode(