<html> <head> <base href="https://bugs.freedesktop.org/" /> </head> <body> <div> <a class="bz_bug_link bz_status_ASSIGNED " title="ASSIGNED - [HSW ULT/BDW]igt/kms_cursor_crc fails with eDP" href="https://bugs.freedesktop.org/show_bug.cgi?id=72864#c19">Comment # 19</a> on <a class="bz_bug_link bz_status_ASSIGNED " title="ASSIGNED - [HSW ULT/BDW]igt/kms_cursor_crc fails with eDP" href="https://bugs.freedesktop.org/show_bug.cgi?id=72864">bug 72864</a> from <a class="email" href="mailto:huax.lu@intel.com" title="lu hua <huax.lu@intel.com>"> lu hua</a> <pre>Created <a href="attachment.cgi?id=107757" name="attach_107757" title="output">attachment 107757</a> <a href="attachment.cgi?id=107757&action=edit" title="output">[details]</a> output (In reply to Paulo Zanoni from <a href="show_bug.cgi?id=72864#c18">comment #18</a>) > Ok, so I did some more investigation... The problem only appears to happen > on pipe A. Arthur suggested that some package C state may be interfering > with memory/caches, and the HW is calculating CRC the result based on a > wrong input. > > So I did some test, and if we keep the i915_forcewake_user file open, the > problem _does not_ happen. > > The easiest way I found to test this is: > > - open a terminal > - become root > - run "irb" > - on its prompt, type: "a = > File.open("/sys/kernel/debug/dri/0/i915_forcewake_user")" > - leave this terminal as it is > - open a new terminal > - run sudo ./kms_cursor_crc > > The test will succeed! > > For the real fix, I guess we have to find a way to prevent deep PC states > whenever we're calculating CRCs for pipe A... Attached output.</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>