<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_NEEDINFO " title="NEEDINFO - [HSW] linux next-20170407+ boots to a blank screen" href="https://bugs.freedesktop.org/show_bug.cgi?id=100755#c19">Comment # 19</a> on <a class="bz_bug_link bz_status_NEEDINFO " title="NEEDINFO - [HSW] linux next-20170407+ boots to a blank screen" href="https://bugs.freedesktop.org/show_bug.cgi?id=100755">bug 100755</a> from <a class="email" href="mailto:jani.nikula@intel.com" title="Jani Nikula <jani.nikula@intel.com>"> Jani Nikula</a> <pre>(In reply to Rafael Ristovski from <a href="show_bug.cgi?id=100755#c17">comment #17</a>) > You can see a clear difference: Yeah. The link M and N values are used to regenerate the pixel clock from the link clock on the sink side. Regenrated pixel clock = M / N * link clock. They are 24 bit values, and per the DP spec the source can choose them freely, as long as they are within the error boundaries described in <a href="show_bug.cgi?id=100755#c12">comment #12</a>. Except now we have sinks that fail on some values, and some other sinks that fail on some other values. I am not amused. Pixel clock 69300: > Good: > [1.710939] [drm:intel_dump_pipe_config] dp m_n: lanes: 2; gmch_m: 2422210, > gmch_n: 8388608, link_m: 134567, link_n: 524288, tu: 64 Regenerated pixel clock 69299.869537354. We don't know whether the sink rounds that to 69299 or 69300. > Bad: > [1.708518] [drm:intel_dump_pipe_config] dp m_n: lanes: 2; gmch_m: 302776, > gmch_n: 1048576, link_m: 33642, link_n: 131072, tu: 64 Regenerated pixel clock with the rounding patch 69300.384521484 and without the rounding patch 69298.324584961. They should be rounded to 69300 and 69298, respectively. I don't see a whole lot of difference here. Except that the sinks don't know how to count.</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> </ul> </body> </html>