1. 19 Feb, 2015 4 commits
    • Andy Lutomirski's avatar
      x86, vdso: Use asm volatile in __getcpu · 9b1cb2c9
      Andy Lutomirski authored
      commit 1ddf0b1b upstream.
      
      In Linux 3.18 and below, GCC hoists the lsl instructions in the
      pvclock code all the way to the beginning of __vdso_clock_gettime,
      slowing the non-paravirt case significantly.  For unknown reasons,
      presumably related to the removal of a branch, the performance issue
      is gone as of
      
      e76b027e x86,vdso: Use LSL unconditionally for vgetcpu
      
      but I don't trust GCC enough to expect the problem to stay fixed.
      
      There should be no correctness issue, because the __getcpu calls in
      __vdso_vlock_gettime were never necessary in the first place.
      
      Note to stable maintainers: In 3.18 and below, depending on
      configuration, gcc 4.9.2 generates code like this:
      
           9c3:       44 0f 03 e8             lsl    %ax,%r13d
           9c7:       45 89 eb                mov    %r13d,%r11d
           9ca:       0f 03 d8                lsl    %ax,%ebx
      
      This patch won't apply as is to any released kernel, but I'll send a
      trivial backported version if needed.
      
      [
       Backported by Andy Lutomirski.  Should apply to all affected
       versions.  This fixes a functionality bug as well as a performance
       bug: buggy kernels can infinite loop in __vdso_clock_gettime on
       affected compilers.  See, for exammple:
      
       https://bugzilla.redhat.com/show_bug.cgi?id=1178975
      ]
      
      Fixes: 51c19b4f x86: vdso: pvclock gettime support
      Cc: Marcelo Tosatti <mtosatti@redhat.com>
      Acked-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      Signed-off-by: default avatarAndy Lutomirski <luto@amacapital.net>
      [ luis: backported to 3.16: used Andy's backport for stable kernels ]
      Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
      Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
      9b1cb2c9
    • Ville Syrjälä's avatar
      drm/i915: Don't call intel_prepare_page_flip() multiple times on gen2-4 · 5d9fbd6d
      Ville Syrjälä authored
      commit 7d47559e upstream.
      
      The flip stall detector kicks in when pending>=INTEL_FLIP_COMPLETE. That
      means if we first call intel_prepare_page_flip() but don't call
      intel_finish_page_flip(), the next stall check will erroneosly think
      the page flip was somehow stuck.
      
      With enough debug spew emitted from the interrupt handler my 830 hangs
      when this happens. My theory is that the previous vblank interrupt gets
      sufficiently delayed that the handler will see the pending bit set in
      IIR, but ISR still has the bit set as well (ie. the flip was processed
      by CS but didn't complete yet). In this case the handler will proceed
      to call intel_check_page_flip() immediately after
      intel_prepare_page_flip(). It then tries to print a backtrace for the
      stuck flip WARN, which apparetly results in way too much debug spew
      delaying interrupt processing further. That then seems to cause an
      endless loop in the interrupt handler, and the machine is dead until
      the watchdog kicks in and reboots. At least limiting the number of
      iterations of the loop in the interrupt handler also prevented the
      hang.
      
      So it seems better to not call intel_prepare_page_flip() without
      immediately calling intel_finish_page_flip(). The IIR/ISR trickery
      avoids races here so this is a perfectly safe thing to do.
      
      v2: Fix typo in commit message (checkpatch)
      
      Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=88381
      Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=85888Reviewed-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
      Signed-off-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
      Signed-off-by: default avatarJani Nikula <jani.nikula@intel.com>
      Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
      5d9fbd6d
    • Ville Syrjälä's avatar
      drm/i915: Don't swap planes on 830M · 4abd5e6a
      Ville Syrjälä authored
      commit 38af6096 upstream.
      
      Looks like 830M doesn't quite like it when you try to move a plane from
      one pipe to another. It seems that the plane's old pipe has to be active
      even if the plane is already disabled, otherwise the relevant register
      just won't accept new values.
      
      The following commit:
      
       commit 1f1c2e24
       Author: Ville Syrjälä <ville.syrjala@linux.intel.com>
       Date:   Thu Nov 28 17:30:01 2013 +0200
      
          drm/i915: Swap primary planes on gen2 for FBC
      
      caused a regression on 830M. It will attempt to swap the planes when the
      driver is loaded, but at that time only pipe A might be active, so plane
      A gets disabled, but plane B won't get enabled since pipe B is not
      active when we try to move the plane over to pipe A.
      
      There's no reason to swap planes on 830M since it doesn't support
      FBC. Change the logic a bit to limit the plane swapping to platforms
      which actually support FBC. This should avoid getting a black screen on
      830M.
      Signed-off-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
      Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
      Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
      4abd5e6a
    • Ville Syrjälä's avatar
      drm/i915: Swap primary planes on gen2 for FBC · a1e50408
      Ville Syrjälä authored
      commit 1f1c2e24 upstream.
      
      Only plane A is FBC capable on gen2 (like gen3), but the panel fitter
      is hooked up to pipe B, so we want to prefer pipe B + plane A.
      Signed-off-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
      Reviewed-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
      [danvet: Add the code comment Chris requested in his review.]
      Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
      [ kamal: 3.13-stable prereq for: 7d47559e
        "drm/i915: Don't call intel_prepare_page_flip() multiple times on gen2-4" ]
      Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
      a1e50408
  2. 18 Feb, 2015 14 commits
  3. 10 Feb, 2015 1 commit
  4. 09 Feb, 2015 3 commits
  5. 03 Feb, 2015 1 commit
  6. 29 Jan, 2015 17 commits