gpu: nvgpu: don't run cde shader for 0 ctaglines

If the associated buffer is not compressed, it would be invalid to call
the cde swizzler shader with zero lines. The fences in
PREPARE_COMPRESSIBLE_READ still need to be managed, so just do a dummy
submit with zero entries when lines is zero for the buffer.

Bug 1856088

Change-Id: Ia68c2ffff21e5e8077d5c550b0ca44090f88bf80
Signed-off-by: Konsta Holtta <kholtta@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1590055
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

2 files changed, 29 insertions, 9 deletions

diff --git a/drivers/gpu/nvgpu/common/linux/cde.c b/drivers/gpu/nvgpu/common/linux/cde.c
index c4f678b6..b48c498d 100644
--- a/drivers/gpu/nvgpu/common/linux/cde.c
+++ b/drivers/gpu/nvgpu/common/linux/cde.c
@@ -759,12 +759,16 @@ static int gk20a_cde_execute_buffer(struct gk20a_cde_ctx *cde_ctx,
         } else if (op == TYPE_BUF_COMMAND_CONVERT) {
                 gpfifo = cde_ctx->convert_cmd;
                 num_entries = cde_ctx->convert_cmd_num_entries;
+        } else if (op == TYPE_BUF_COMMAND_NOOP) {
+                /* Any non-null gpfifo will suffice with 0 num_entries */
+                gpfifo = cde_ctx->init_convert_cmd;
+                num_entries = 0;
         } else {
                 nvgpu_warn(g, "cde: unknown buffer");
                 return -EINVAL;
         }
 
-        if (gpfifo == NULL || num_entries == 0) {
+        if (gpfifo == NULL) {
                 nvgpu_warn(g, "cde: buffer not available");
                 return -ENOSYS;
         }
@@ -990,6 +994,7 @@ __releases(&l->cde_app->mutex)
         u32 flags;
         int err, i;
         const s16 compbits_kind = 0;
+        u32 submit_op;
 
         gk20a_dbg(gpu_dbg_cde, "compbits_byte_offset=%llu scatterbuffer_byte_offset=%llu",
                   compbits_byte_offset, scatterbuffer_byte_offset);
@@ -1162,15 +1167,29 @@ __releases(&l->cde_app->mutex)
         /* gk20a_cde_execute_buffer() will grab a power reference of it's own */
         gk20a_idle(g);
 
-        /* execute the conversion buffer, combined with init first if it's the
-         * first time */
-        err = gk20a_cde_execute_buffer(cde_ctx,
-                        cde_ctx->init_cmd_executed
-                                ? TYPE_BUF_COMMAND_CONVERT
-                                : TYPE_BUF_COMMAND_INIT,
+        if (comptags.lines == 0) {
+                /*
+                 * Nothing to do on the buffer, but do a null kickoff for
+                 * managing the pre and post fences.
+                 */
+                submit_op = TYPE_BUF_COMMAND_NOOP;
+        } else if (!cde_ctx->init_cmd_executed) {
+                /*
+                 * First time, so include the init pushbuf too in addition to
+                 * the conversion code.
+                 */
+                submit_op = TYPE_BUF_COMMAND_INIT;
+        } else {
+                /*
+                 * The usual condition: execute just the conversion.
+                 */
+                submit_op = TYPE_BUF_COMMAND_CONVERT;
+        }
+        err = gk20a_cde_execute_buffer(cde_ctx, submit_op,
                         fence, flags, fence_out);
 
-        cde_ctx->init_cmd_executed = true;
+        if (comptags.lines != 0 && !err)
+                cde_ctx->init_cmd_executed = true;
 
         /* unmap the buffers - channel holds references to them now */
         nvgpu_vm_unmap(cde_ctx->vm, map_vaddr, NULL);
diff --git a/drivers/gpu/nvgpu/common/linux/cde.h b/drivers/gpu/nvgpu/common/linux/cde.h
index 5dd15c37..fe206401 100644
--- a/drivers/gpu/nvgpu/common/linux/cde.h
+++ b/drivers/gpu/nvgpu/common/linux/cde.h
@@ -160,7 +160,8 @@ struct gk20a_cde_hdr_command {
 
 enum {
         TYPE_BUF_COMMAND_INIT = 0,
-        TYPE_BUF_COMMAND_CONVERT
+        TYPE_BUF_COMMAND_CONVERT,
+        TYPE_BUF_COMMAND_NOOP
 };
 
 /*