drm: Honor modes selected by the user through video= kernel cmdline argument

Before this commit we would skip preferred-mode selection if a video=
kernel cmdline is argument, instead relying on the kernel to have activated
all the outputs and then we would inherit those modes.

But this relies on fbcon having initialized the outputs, which it does not
do when deferred-fbcon-takeover is used. Deferred-fbcon-takeover is
necessary for flickerfree boot, so this is now the default in many distros.

Instead of relying on the kernel having setup everything for us, honor
the video= mode selection by checking for modes with a DRM_MODE_TYPE_USERDEF
flag before checking for modes with a DRM_MODE_TYPE_PREFERRED flag.

Note that the DRM_MODE_TYPE_USERDEF flag is only ever set based on a
video= argument. So on systems without a video= argument on the kernel
cmdline nothing changes.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>

diff --git a/src/plugins/renderers/drm/plugin.c b/src/plugins/renderers/drm/plugin.c
index 4dbf8da8dca952cb626850185b06680da190aa38..1f222af9727fb463f19fbb7abc89b049c2eec26f 100644 (file)
--- a/src/plugins/renderers/drm/plugin.c
+++ b/src/plugins/renderers/drm/plugin.c
@@ -157,7 +157,6 @@ struct _ply_renderer_backend
 
         uint32_t                         is_active : 1;
         uint32_t        requires_explicit_flushing : 1;
-        uint32_t                use_preferred_mode : 1;
 
         int                              panel_width;
         int                              panel_height;
@@ -171,23 +170,6 @@ static bool open_input_source (ply_renderer_backend_t      *backend,
 static void flush_head (ply_renderer_backend_t *backend,
                         ply_renderer_head_t    *head);
 
-/* A small helper to determine if we should try to keep the current mode
- * or pick the best mode ourselves, we keep the current mode only if the
- * user specified a specific mode using video= on the commandline.
- */
-static bool
-should_use_preferred_mode (void)
-{
-        bool use_preferred_mode = true;
-
-        if (ply_kernel_command_line_get_string_after_prefix ("video="))
-                use_preferred_mode = false;
-
-        ply_trace ("should_use_preferred_mode: %d", use_preferred_mode);
-
-        return use_preferred_mode;
-}
-
 static bool
 ply_renderer_buffer_map (ply_renderer_backend_t *backend,
                          ply_renderer_buffer_t  *buffer)
@@ -903,7 +885,6 @@ create_backend (const char     *device_name,
         backend->output_buffers = ply_hashtable_new (ply_hashtable_direct_hash,
                                                      ply_hashtable_direct_compare);
         backend->heads_by_controller_id = ply_hashtable_new (NULL, NULL);
-        backend->use_preferred_mode = should_use_preferred_mode ();
 
         return backend;
 }
@@ -1133,6 +1114,14 @@ get_preferred_mode (drmModeConnector *connector)
 {
         int i;
 
+        for (i = 0; i < connector->count_modes; i++)
+                if (connector->modes[i].type & DRM_MODE_TYPE_USERDEF) {
+                        ply_trace ("Found user set mode %dx%d at index %d",
+                                   connector->modes[i].hdisplay,
+                                   connector->modes[i].vdisplay, i);
+                        return &connector->modes[i];
+                }
+
         for (i = 0; i < connector->count_modes; i++)
                 if (connector->modes[i].type & DRM_MODE_TYPE_PREFERRED) {
                         ply_trace ("Found preferred mode %dx%d at index %d",
@@ -1190,7 +1179,7 @@ get_output_info (ply_renderer_backend_t *backend,
         output_get_controller_info (backend, connector, output);
         ply_renderer_connector_get_rotation_and_tiled (backend, connector, output);
 
-        if (!output->tiled && backend->use_preferred_mode)
+        if (!output->tiled)
                 mode = get_preferred_mode (connector);
 
         if (!mode && output->controller_id)