On Tue, Feb 25, 2014 at 5:33 AM, Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > On Mon, Feb 24, 2014 at 04:20:04PM -0600, Daniel Drake wrote: >> Working with HDMI TVs is a real pain as they tend to overscan by >> default, meaning that the pixels around the edge of the framebuffer >> are not displayed. This is well explained here: >> http://mjg59.dreamwidth.org/8705.html >> >> There is a bit in the HDMI info frame that can request that the >> remote display shows the full pixel data ("underscan"). For the >> remote display, the HDMI spec states that this is optional - it >> doesn't have to listen. That means that most TVs will probably ignore >> this. >> >> But, maybe there are a handful of TVs for which this would help >> the situation. As we live in a digital world, ask the remote >> display not to overscan by default. >> >> Signed-off-by: Daniel Drake <drake@xxxxxxxxxxxx> > > Yeah, underscan would seem the saner default value. CEA-861 says that > the source should always set the S bits appropriately if it knows what > to put there, even if the sink claims that it won't respect those bits. > So we're not violating the spec by doing this. > > I'm thinking we should also add a connector property to allow userspace > to choose the scan behaviour. Or perhaps some driver already has such a > property? > We have an underscan connector property in the radeon driver, but it uses the scaler to underscan the image to compensate for TV's that overscan by default, so it's not really a good match for this. Alex > I'm not sure we want to put this into hdmi.c though. Maybe better to > avoid such policy in the infoframe code itself, and instead stick this > into drm_hdmi_avi_infoframe_from_display_mode()? > >> --- >> drivers/video/hdmi.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/drivers/video/hdmi.c b/drivers/video/hdmi.c >> index 9e758a8..6c2d924 100644 >> --- a/drivers/video/hdmi.c >> +++ b/drivers/video/hdmi.c >> @@ -54,6 +54,7 @@ int hdmi_avi_infoframe_init(struct hdmi_avi_infoframe *frame) >> frame->type = HDMI_INFOFRAME_TYPE_AVI; >> frame->version = 2; >> frame->length = HDMI_AVI_INFOFRAME_SIZE; >> + frame->scan_mode = HDMI_SCAN_MODE_UNDERSCAN; >> >> return 0; >> } >> -- >> 1.8.3.2 >> >> _______________________________________________ >> dri-devel mailing list >> dri-devel@xxxxxxxxxxxxxxxxxxxxx >> http://lists.freedesktop.org/mailman/listinfo/dri-devel > > -- > Ville Syrjälä > Intel OTC > _______________________________________________ > dri-devel mailing list > dri-devel@xxxxxxxxxxxxxxxxxxxxx > http://lists.freedesktop.org/mailman/listinfo/dri-devel _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
