On Fri, Oct 15, 2021 at 10:33:29PM +0300, Ville Syrjälä wrote:

On Fri, Oct 15, 2021 at 09:24:06PM +0200, Claudio Suarez wrote:

...

On Fri, Oct 15, 2021 at 03:03:13PM +0300, Ville Syrjälä wrote:

...

On Fri, Oct 15, 2021 at 01:36:59PM +0200, Claudio Suarez wrote:

...

According to the documentation, drm_add_edid_modes "... Also fills out the &drm_display_info structure and ELD in @connector with any information which can be derived from the edid."

drm_add_edid_modes accepts a struct edid *edid parameter which may have a value or may be null. When it is not null, connector->display_info and connector->eld are updated according to the edid. When edid=NULL, only connector->eld is reset. Reset connector->display_info to be consistent and accurate.

Signed-off-by: Claudio Suarez cssk@net-c.es

drivers/gpu/drm/drm_edid.c | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index 6325877c5fd6..6cbe09b2357c 100644 --- a/drivers/gpu/drm/drm_edid.c +++ b/drivers/gpu/drm/drm_edid.c @@ -5358,10 +5358,12 @@ int drm_add_edid_modes(struct drm_connector *connector, struct edid *edid)

if (edid == NULL) { clear_eld(connector);

• drm_reset_display_info(connector);
  

  return 0; } if (!drm_edid_is_valid(edid)) { clear_eld(connector);

• drm_reset_display_info(connector);
  

Looks easier if you pull both of those out from these branches and just call them unconditionally at the start.

After looking at the full code, I am not sure. This is the code:

int drm_add_edid_modes(struct drm_connector *connector, struct edid *edid) { int num_modes = 0; u32 quirks;

    if (edid == NULL) {
            clear_eld(connector);
            drm_reset_display_info(connector); <--- added by me
            return 0;
    }
    if (!drm_edid_is_valid(edid)) {
            clear_eld(connector);
            drm_reset_display_info(connector); <--- added by me
            drm_warn(connector->dev, "%s: EDID invalid.\n",
                     connector->name);
            return 0;
    }

    drm_edid_to_eld(connector, edid);

    quirks = drm_add_display_info(connector, edid);

etc...

If we move those out of these branches and edid != NULL, we are executing an unnecessary clear_eld(connector) and an unnecessary drm_reset_display_info(connector) because the fields will be set in the next drm_edid_to_eld(connector, edid) and drm_add_display_info(connector, edid)

Do we want this ?

Seems fine by me. And maybe we could nuke the second drm_reset_display_info() from deeper inside drm_add_display_info()? Not sure if drm_add_display_info() still has to be able to operate standalone or not.

Hmm. Another option is to just move all these NULL/invalid edid checks into drm_edid_to_eld() and drm_add_display_info().

But maybe that's not so easy. Would still need to bail out from drm_add_edid_modes() I guess.