<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_REOPENED " title="REOPENED - Screen flickering after getting hpd irq" href="https://bugs.freedesktop.org/show_bug.cgi?id=105267#c19">Comment # 19</a> on <a class="bz_bug_link bz_status_REOPENED " title="REOPENED - Screen flickering after getting hpd irq" href="https://bugs.freedesktop.org/show_bug.cgi?id=105267">bug 105267</a> from <a class="email" href="mailto:perry_yuan@dell.com" title="Perry Yuan <perry_yuan@dell.com>"> Perry Yuan</a> <pre>(In reply to Jani Nikula from <a href="show_bug.cgi?id=105267#c15">comment #15</a>) > Thanks for testing. > > The problem with the patch referenced in <a href="show_bug.cgi?id=105267#c10">comment #10</a> is that will regress > older platforms. We can't do that. > > The background is that we have tried to use optimal link parameters, and we > have tried to optimize for both fewer lanes with higher rate, and more lanes > with lower rate. All of this failed, until we learned that, uh, a certain > other OS always used the maximum link parameters reported by the display. > Apparently that was the only configuration that the panel/laptop vendors > then ended up validating. We switched to using max link rate and lane count, > which presumably correspond to the native resolution of the display anyway, > and we haven't had issues with that approach until now. > > Arguably all the displays should work with all the lane counts and rates > they report, but sadly this appears not to be the case. In this bug, the > display does not work with the maximum parameters it reports. > > Apparently nobody has double checked the DDI buffer translation and voltage > swing etc. parameters that I suggested in <a href="show_bug.cgi?id=105267#c5">comment #5</a>. :( > > eDP 1.4 also adds two somewhat related features. Link rate select to support > more intermediate rates between what's available for DP. DSC to support > stream compression. > > 1) Please attach /sys/kernel/debug/dri/0/i915_vbt. The VBT is supposed to > contain the port specific maximums, but perhaps that's not being used. > > 2) Please see that you have CONFIG_DRM_DP_AUX_CHARDEV=y, and try to use > /dev/drm_dp_auxN node to hexdump the DPCD, and attach them. Hi Jani: If the patch has regression effect，then what we can do to fix the issue ? Perry</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are on the CC list for the bug.</li> <li>You are the QA Contact for the bug.</li> <li>You are the assignee for the bug.</li> </ul> </body> </html>