<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_ASSIGNED " title="ASSIGNED - [IVB bisected] *ERROR* uncleared fifo underrun on pipe A" href="https://bugs.freedesktop.org/show_bug.cgi?id=95736#c20">Comment # 20</a> on <a class="bz_bug_link bz_status_ASSIGNED " title="ASSIGNED - [IVB bisected] *ERROR* uncleared fifo underrun on pipe A" href="https://bugs.freedesktop.org/show_bug.cgi?id=95736">bug 95736</a> from <a class="email" href="mailto:tomeu@tomeuvizoso.net" title="Tomeu Vizoso <tomeu@tomeuvizoso.net>"> Tomeu Vizoso</a> <pre>(In reply to Fabian Henze from <a href="show_bug.cgi?id=95736#c19">comment #19</a>) > (In reply to Tomeu Vizoso from <a href="show_bug.cgi?id=95736#c18">comment #18</a>) > > Hi, I think 10 would be a bit too little. I would expect the value to be > > between 12 and 20, but maybe more could be needed. > > I tried a few values between 13 and 100 (13, 20, 50 and 100 iirc) and all > had the fifo underrun. What now ...? So, your last log showed this: [ 1.034165] [drm:gen6_check_mch_setup] Wrong MCH_SSKPD value: 0x16040307 This can cause underruns. This usually means that the BIOS programmed a too low priority (ox7 instead of 0xc) for memory requests from the display, but that register is locked by when the kernel starts so we cannot fix it. I see your machine currently has fw 1.42 and there's a 1.43 available from Lenovo's support site, but the BIOS changelog doesn't mention such a fix. It may be worth it anyway to upgrade the BIOS to 1.43. In the kernel sources it's mentioned that when the BIOS has such a bug and it cannot be updated to a fixed version, that the issue can only be worked around by increasing the latencies. It may still be worth it though to check that the watermarks are programmed at the right values. But you report that fixing up the latencies above 12 didn't help, so we might not be able to do anything about it other than hiding the message.</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>