<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW - LSPCon and DisplayPort always output limited range RGB, even when it should output full range RGB" href="https://bugs.freedesktop.org/show_bug.cgi?id=100023#c1">Comment # 1</a> on <a class="bz_bug_link bz_status_NEW " title="NEW - LSPCon and DisplayPort always output limited range RGB, even when it should output full range RGB" href="https://bugs.freedesktop.org/show_bug.cgi?id=100023">bug 100023</a> from <a class="email" href="mailto:nw9165-3201@yahoo.com" title="N. W. <nw9165-3201@yahoo.com>"> N. W.</a> <pre>Relevant quote from <a class="bz_bug_link bz_status_RESOLVED bz_closed" title="RESOLVED FIXED - MegaChips MCDP2800 LSPCON and ASRock Fatal1ty Z170 Gaming-ITX/ac issues (Broadcast RGB, HDMI output, triple monitor not working)" href="show_bug.cgi?id=94248#c94">https://bugs.freedesktop.org/show_bug.cgi?id=94248#c94</a> : (In reply to Ville Syrjala from <a href="show_bug.cgi?id=100023#c94">comment #94</a>) > > [ 12.431104] [drm:intel_atomic_check [i915]] [CONNECTOR:56:HDMI-A-2] > checking for sink bpp constrains > [ 12.431151] [drm:intel_atomic_check [i915]] clamping display bpp (was 36) > to default limit of 24 > [ 12.431201] [drm:intel_hdmi_compute_config [i915]] picking bpc to 8 for > HDMI output > [ 12.431246] [drm:intel_hdmi_compute_config [i915]] forcing pipe bpc to 24 > for HDMI > [ 12.431293] [drm:intel_atomic_check [i915]] hw max bpp: 36, pipe bpp: 24, > dithering: 0 > [ 12.431359] [drm:intel_dump_pipe_config [i915]] [CRTC:31:pipe A][modeset] > [ 12.431403] [drm:intel_dump_pipe_config [i915]] cpu_transcoder: A, pipe > bpp: 24, dithering: 0 > [ 12.431446] [drm:intel_dump_pipe_config [i915]] audio: 0, infoframes: 0 > > That "infoframes: 0" part is telling me that your display likely doesn't > identify itself as supporting HDMI, so we treat it as DVI and decide to send > it full range data instead of limited range data. But for DP (which is what > LSPCON is for us) we don't make that distinction. Unfortunately the DP spec > doesn't make any useful provisions for these kinds of combinations. so we're > basically left to guess what we should be doing. > > I think what we might want to do is send full range data regardless of the > timings when dealing with a DVI/HDMI downstream port and the monitor doesn't > identify itself as HDMI compatible (essentially using the same logic as we > use for native HDMI). DP++ downstream port might more difficult since I > don't recall if we can somehow tell if the plugged in monitor is actually > DVI/HDMI or DP (I'll need to look into this a bit more). For > VGA/NO_EDID/whatnot downstream ports sending full range all the time might > be the right choice.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the QA Contact for the bug.</li> <li>You are on the CC list for the bug.</li> <li>You are the assignee for the bug.</li> </ul> </body> </html>