Re: [PATCH libdrm v1 2/2] tests/modetest: Add support for writeback connector

[Rohith Iyer]

Hi Andy,

On 7/25/2022 6:57 PM, Andy Yan wrote:

Hi Rohith:




At 2022-07-26 03:26:39, "Rohith Iyer" <quic_rohii...@quicinc.com> wrote:
Add writeback support to modetest with the below options:

+               case 'o':
+                       pipe_args->dump = true;
+                       dump_path = optarg;
+                       break;
                case 'P':
                        plane_args = realloc(plane_args,
                                             (plane_count + 1) * sizeof 
*plane_args);
@@ -2098,6 +2173,7 @@ int main(int argc, char **argv)
                        crtcs = 1;
                        planes = 1;
                        break;
+               case 'x':
                case 's':
                        pipe_args = realloc(pipe_args,
                                            (count + 1) * sizeof *pipe_args);
@@ -2109,7 +2185,7 @@ int main(int argc, char **argv)

                        if (parse_connector(&pipe_args[count], optarg) < 0)
                                usage(argv[0]);
-
+                       pipe_args->custom = (c == 'x');
                        count++;
                        break;
                case 'C':
@@ -2165,6 +2241,7 @@ int main(int argc, char **argv)

        if (use_atomic) {
                ret = drmSetClientCap(dev.fd, DRM_CLIENT_CAP_ATOMIC, 1);
+               drmSetClientCap(dev.fd, DRM_CLIENT_CAP_WRITEBACK_CONNECTORS, 1);
                if (ret) {
                        fprintf(stderr, "no atomic modesetting support: %s\n", 
strerror(errno));
                        drmClose(dev.fd);
@@ -2208,6 +2285,8 @@ int main(int argc, char **argv)
                        if (set_preferred || count)
                                set_mode(&dev, pipe_args, count);

+                       writeback_config(&dev, pipe_args, count);
+
                        if (plane_count)
                                atomic_set_planes(&dev, plane_args, 
plane_count, false);

@@ -2217,6 +2296,13 @@ int main(int argc, char **argv)
                                return 1;
                        }




How do we make sure the writeback is finished?  Do we need a writeback fence 
here?

Thanks for pointing this out. We plan to have a function that polls on 
the writeback fence fd, until the writeback is finished. Let me know if 
you have something else in mind.


+                       /*
+                        * Since only writeback connectors have an output fb, 
this should only be
+                        * called for writeback.
+                        */
+                       if (pipe_args->dump)
+                               dump_output_fb(&dev, pipe_args, dump_path, 
count);
+
                        if (test_vsync)
                                atomic_test_page_flip(&dev, pipe_args, 
plane_args, plane_count);

--
2.31.0

Thanks,
Rohith