1. 26 Apr, 2012 1 commit
    • Daniel Vetter's avatar
      drm/i915: handle input/output sdvo timings separately in mode_set · 6651819b
      Daniel Vetter authored
      We seem to have a decent confusion between the output timings and the
      input timings of the sdvo encoder. If I understand the code correctly,
      we use the original mode unchanged for the output timings, safe for
      the lvds case. And we should use the adjusted mode for input timings.
      
      Clarify the situation by adding an explicit output_dtd to the sdvo
      mode_set function and streamline the code-flow by moving the input and
      output mode setting in the sdvo encode together.
      
      Furthermore testing showed that the sdvo input timing needs the
      unadjusted dotclock, the sdvo chip will automatically compute the
      required pixel multiplier to get a dotclock above 100 MHz.
      
      Fix this up when converting a drm mode to an sdvo dtd.
      
      This regression was introduced in
      
      commit c74696b9
      Author: Pavel Roskin <proski@gnu.org>
      Date:   Thu Sep 2 14:46:34 2010 -0400
      
          i915: revert some checks added by commit 32aad86f
      
      particularly the following hunk:
      
      diff --git a/drivers/gpu/drm/i915/intel_sdvo.c
      b/drivers/gpu/drm/i915/intel_sdvo.c
      index 093e914..62d22ae 100644
      --- a/drivers/gpu/drm/i915/intel_sdvo.c
      +++ b/drivers/gpu/drm/i915/intel_sdvo.c
      @@ -1122,11 +1123,9 @@ static void intel_sdvo_mode_set(struct drm_encoder *encoder,
      
           /* We have tried to get input timing in mode_fixup, and filled into
              adjusted_mode */
      -    if (intel_sdvo->is_tv || intel_sdvo->is_lvds) {
      -        intel_sdvo_get_dtd_from_mode(&input_dtd, adjusted_mode);
      +    intel_sdvo_get_dtd_from_mode(&input_dtd, adjusted_mode);
      +    if (intel_sdvo->is_tv || intel_sdvo->is_lvds)
               input_dtd.part2.sdvo_flags = intel_sdvo->sdvo_flags;
      -    } else
      -        intel_sdvo_get_dtd_from_mode(&input_dtd, mode);
      
           /* If it's a TV, we already set the output timing in mode_fixup.
            * Otherwise, the output timing is equal to the input timing.
      
      Due to questions raised in review, below a more elaborate analysis of
      the bug at hand:
      
      Sdvo seems to have two timings, one is the output timing which will be
      sent over whatever is connected on the other side of the sdvo chip (panel,
      hdmi screen, tv), the other is the input timing which will be generated by
      the gmch pipe. It looks like sdvo is expected to scale between the two.
      
      To make things slightly more complicated, we have a bunch of special
      cases:
      - For lvds panel we always use a fixed output timing, namely
        intel_sdvo->sdvo_lvds_fixed_mode, hence that special case.
      - Sdvo has an interface to generate a preferred input timing for a given
        output timing. This is the confusing thing that I've tried to clear up
        with the follow-on patches.
      - A special requirement is that the input pixel clock needs to be between
        100MHz and 200MHz (likely to keep it within the electromechanical design
        range of PCIe), 270MHz on later gen4+. Lower pixel clocks are
        doubled/quadrupled.
      
      The thing this patch tries to fix is that the pipe needs to be
      explicitly instructed to double/quadruple the pixels and needs the
      correspondingly higher pixel clock, whereas the sdvo adaptor seems to
      do that itself and needs the unadjusted pixel clock. For the sdvo
      encode side we already set the pixel mutliplier with a different
      command (0x21).
      
      This patch tries to fix this mess by:
      - Keeping the output mode timing in the unadjusted plain mode, safe
        for the lvds case.
      - Storing the input timing in the adjusted_mode with the adjusted
        pixel clock. This way we don't need to frob around with the core
        crtc mode set code.
      - Fixing up the pixelclock when constructing the sdvo dtd timing
        struct. This is why the first hunk of the patch is an integral part
        of the series.
      - Dropping the is_tv special case because input_dtd is equivalent to
        adjusted_mode after these changes. Follow-up patches clear this up
        further (by simply ripping out intel_sdvo->input_dtd because it's
        not needed).
      
      v2: Extend commit message with an in-depth bug analysis.
      Reported-and-Tested-by: default avatarBernard Blackham <b-linuxgit@largestprime.net>
      Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=48157Reviewed-by: default avatarJesse Barnes <jbarnes@virtuousgeek.org>
      Cc: stable@kernel.org
      Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
      6651819b
  2. 23 Apr, 2012 2 commits
  3. 22 Apr, 2012 1 commit
  4. 21 Apr, 2012 23 commits
  5. 20 Apr, 2012 13 commits