Re: [PATCHv2] drm: fb_helper: prefer to use mode, which is not DRM_MODE_TYPE_USERDEF

Chris Wilson
2015-04-20T10:49:00Z

On Mon, Apr 20, 2015 at 12:38:25PM +0200, Radek Dostál wrote:
> Hi Chris,
>
> On 04/20/2015 11:58 AM, Chris Wilson wrote:
> > Hmm, so that should be before the clock comparison as well to fix your
> > example. Not as neat.
>
> indeed that is required.
>
> > The other idea I was considering was not adding the GTF cmdline mode if
> > the probed modes already contain one of a matching resolution. The goal
> > here is to also not present a mode to userspace that is invalid.
>
> Unfortunately you can not do that. I already tried. At the time when
> drm_helper_probe_add_cmdline_mode is called EDID informations are not
> yet available.

My understanding is that it should be. fb_helper.initial_config does a
probe first, and the intel_fb_initial_config() should only keep the
active mode.

> Only option would be to remove the GTF cmdline mode, when matching mode
> is found in EDID.

So basically

diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
index 6350387..9212bec 100644
--- a/drivers/gpu/drm/drm_probe_helper.c
+++ b/drivers/gpu/drm/drm_probe_helper.c
@@ -79,13 +79,29 @@ drm_mode_validate_flag(const struct drm_display_mode *mode,

static int drm_helper_probe_add_cmdline_mode(struct drm_connector *connector)
{
+ struct drm_cmdline_mode *cmdline_mode;
struct drm_display_mode *mode;

- if (!connector->cmdline_mode.specified)
+ cmdline_mode = &connector->cmdline_mode;
+ if (!cmdline_mode->specified)
return 0;

+ /* Only add a GTF mode if we find no matching probed modes */
+ list_for_each_entry(mode, &connector->modes, head) {
+ if (mode->hdisplay != cmdline_mode->xres ||
+ mode->vdisplay != cmdline_mode->yres)
+ continue;
+
+ if (cmdline_mode->refresh_specified) {
+ if (mode->vrefresh != cmdline_mode->refresh)
+ continue;
+ }
+
+ return 0;
+ }
+
mode = drm_mode_create_from_cmdline_mode(connector->dev,
- &connector->cmdline_mode);
+ cmdline_mode);
if (mode == NULL)
return 0;

is not sufficient?
-Chris

--
Chris Wilson, Intel Open Source Technology Centre