On Wed, 16 May 2018, Dhinakaran Pandiyan <dhinakaran.pandi...@intel.com> wrote:
> On Wed, 2018-05-16 at 11:01 +0300, Jani Nikula wrote:
>> This reverts commit dc911f5bd8aacfcf8aabd5c26c88e04c837a938e.
>> 
>> Per the report, no matter what display mode you select with xrandr,
>> the
>> i915 driver will always select the alternate fixed mode. For the
>> reporter this means that the display will always run at 40Hz which is
>> quite annoying. This may be due to the mode comparison.
>> 
>> But there are some other potential issues. The choice of
>> alt_fixed_mode
>> seems dubious. It's the first non-preferred mode, but there are no
>> guarantees that the only difference would be refresh rate. Similarly,
>> there may be more than one preferred mode in the probed modes list,
>> and
>> the commit changes the preferred mode selection to choose the last
>> one
>> on the list instead of the first.
>> 
>> (Note that the probed modes list is the raw, unfiltered, unsorted
>> list
>> of modes from drm_add_edid_modes(), not the pretty result after a
>> drm_helper_probe_single_connector_modes() call.)
>> 
>> Finally, we already have eerily similar code in place to find the
>> downclock mode for DRRS that seems like could be reused here.
>> 
>> Back to the drawing board.
>> 
>> Note: This is a hand-crafted revert due to conflicts. If it fails to
>> backport, please just try reverting the original commit directly.
>> 
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105469
>> Reported-by: Rune Petersen <r...@megahurts.dk>
>> Reported-by: Mark Spencer <n7u4722...@ynzlx.anonbox.net>
>> Fixes: dc911f5bd8aa ("drm/i915/edp: Allow alternate fixed mode for
>> eDP if available.")
>> Cc: Clint Taylor <clinton.a.tay...@intel.com>
>> Cc: David Weinehall <david.weineh...@linux.intel.com>
>> Cc: Rodrigo Vivi <rodrigo.v...@intel.com>
>> Cc: Paulo Zanoni <paulo.r.zan...@intel.com>
>> Cc: Jani Nikula <jani.nik...@intel.com>
>> Cc: Chris Wilson <ch...@chris-wilson.co.uk>
>> Cc: Jim Bride <jim.br...@linux.intel.com>
>> Cc: Jani Nikula <jani.nik...@linux.intel.com>
>> Cc: Joonas Lahtinen <joonas.lahti...@linux.intel.com>
>> Cc: intel-gfx@lists.freedesktop.org
>> Cc: <sta...@vger.kernel.org> # v4.14+
>> Signed-off-by: Jani Nikula <jani.nik...@intel.com>
>> ---
>>  drivers/gpu/drm/i915/intel_dp.c    | 38 +++++-----------------------
>> ----------
>>  drivers/gpu/drm/i915/intel_drv.h   |  2 --
>>  drivers/gpu/drm/i915/intel_dsi.c   |  2 +-
>>  drivers/gpu/drm/i915/intel_dvo.c   |  2 +-
>>  drivers/gpu/drm/i915/intel_lvds.c  |  3 +--
>>  drivers/gpu/drm/i915/intel_panel.c |  6 ------
>>  6 files changed, 8 insertions(+), 45 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/i915/intel_dp.c
>> b/drivers/gpu/drm/i915/intel_dp.c
>> index dde92e4af5d3..8320f0e8e3be 100644
>> --- a/drivers/gpu/drm/i915/intel_dp.c
>> +++ b/drivers/gpu/drm/i915/intel_dp.c
>> @@ -1679,23 +1679,6 @@ static int intel_dp_compute_bpp(struct
>> intel_dp *intel_dp,
>>      return bpp;
>>  }
>>  
>> -static bool intel_edp_compare_alt_mode(struct drm_display_mode *m1,
>> -                                   struct drm_display_mode *m2)
>> -{
>> -    bool bres = false;
>> -
>> -    if (m1 && m2)
>> -            bres = (m1->hdisplay == m2->hdisplay &&
>> -                    m1->hsync_start == m2->hsync_start &&
>> -                    m1->hsync_end == m2->hsync_end &&
>> -                    m1->htotal == m2->htotal &&
>> -                    m1->vdisplay == m2->vdisplay &&
>> -                    m1->vsync_start == m2->vsync_start &&
>> -                    m1->vsync_end == m2->vsync_end &&
>> -                    m1->vtotal == m2->vtotal);
>> -    return bres;
>> -}
>> -
>>  /* Adjust link config limits based on compliance test requests. */
>>  static void
>>  intel_dp_adjust_compliance_config(struct intel_dp *intel_dp,
>> @@ -1860,16 +1843,8 @@ intel_dp_compute_config(struct intel_encoder
>> *encoder,
>>              pipe_config->has_audio = intel_conn_state-
>> >force_audio == HDMI_AUDIO_ON;
>>  
>>      if (intel_dp_is_edp(intel_dp) && intel_connector-
>> >panel.fixed_mode) {
>> -            struct drm_display_mode *panel_mode =
>> -                    intel_connector->panel.alt_fixed_mode;
>> -            struct drm_display_mode *req_mode = &pipe_config-
>> >base.mode;
>> -
>> -            if (!intel_edp_compare_alt_mode(req_mode,
>> panel_mode))
>> -                    panel_mode = intel_connector-
>> >panel.fixed_mode;
>> -
>> -            drm_mode_debug_printmodeline(panel_mode);
>> -
>> -            intel_fixed_panel_mode(panel_mode, adjusted_mode);
>> +            intel_fixed_panel_mode(intel_connector-
>> >panel.fixed_mode,
>> +                                   adjusted_mode);
>>  
>>              if (INTEL_GEN(dev_priv) >= 9) {
>>                      int ret;
>> @@ -6159,7 +6134,6 @@ static bool intel_edp_init_connector(struct
>> intel_dp *intel_dp,
>>      struct drm_i915_private *dev_priv = to_i915(dev);
>>      struct drm_connector *connector = &intel_connector->base;
>>      struct drm_display_mode *fixed_mode = NULL;
>> -    struct drm_display_mode *alt_fixed_mode = NULL;
>>      struct drm_display_mode *downclock_mode = NULL;
>>      bool has_dpcd;
>>      struct drm_display_mode *scan;
>> @@ -6214,14 +6188,13 @@ static bool intel_edp_init_connector(struct
>> intel_dp *intel_dp,
>>      }
>>      intel_connector->edid = edid;
>>  
>> -    /* prefer fixed mode from EDID if available, save an alt
>> mode also */
>> +    /* prefer fixed mode from EDID if available */
>>      list_for_each_entry(scan, &connector->probed_modes, head) {
>>              if ((scan->type & DRM_MODE_TYPE_PREFERRED)) {
>>                      fixed_mode = drm_mode_duplicate(dev, scan);
>>                      downclock_mode = intel_dp_drrs_init(
>>                                              intel_connector,
>> fixed_mode);
>> -            } else if (!alt_fixed_mode) {
>> -                    alt_fixed_mode = drm_mode_duplicate(dev,
>> scan);
>> +                    break;
>
> If multiple preferred modes are present, we'll now end up calling
> drrs_init() only for the first. I see that this is what the original
> code did but this revert does more than removing support for alternate
> modes.

It boils down to which preferred mode is *the* preferred mode. I think
the original code was, uh, preferrable. Note that drrs init scans the
entire list of modes again to find the same size mode with the lowest
refresh rate.

BR,
Jani.

>
>>              }
>>      }
>>  
>> @@ -6258,8 +6231,7 @@ static bool intel_edp_init_connector(struct
>> intel_dp *intel_dp,
>>                            pipe_name(pipe));
>>      }
>>  
>> -    intel_panel_init(&intel_connector->panel, fixed_mode,
>> alt_fixed_mode,
>> -                     downclock_mode);
>> +    intel_panel_init(&intel_connector->panel, fixed_mode,
>> downclock_mode);
>>      intel_connector->panel.backlight.power =
>> intel_edp_backlight_power;
>>      intel_panel_setup_backlight(connector, pipe);
>>  
>> diff --git a/drivers/gpu/drm/i915/intel_drv.h
>> b/drivers/gpu/drm/i915/intel_drv.h
>> index d7dbca1aabff..0361130500a6 100644
>> --- a/drivers/gpu/drm/i915/intel_drv.h
>> +++ b/drivers/gpu/drm/i915/intel_drv.h
>> @@ -277,7 +277,6 @@ struct intel_encoder {
>>  
>>  struct intel_panel {
>>      struct drm_display_mode *fixed_mode;
>> -    struct drm_display_mode *alt_fixed_mode;
>>      struct drm_display_mode *downclock_mode;
>>  
>>      /* backlight */
>> @@ -1850,7 +1849,6 @@ void intel_overlay_reset(struct
>> drm_i915_private *dev_priv);
>>  /* intel_panel.c */
>>  int intel_panel_init(struct intel_panel *panel,
>>                   struct drm_display_mode *fixed_mode,
>> -                 struct drm_display_mode *alt_fixed_mode,
>>                   struct drm_display_mode *downclock_mode);
>>  void intel_panel_fini(struct intel_panel *panel);
>>  void intel_fixed_panel_mode(const struct drm_display_mode
>> *fixed_mode,
>> diff --git a/drivers/gpu/drm/i915/intel_dsi.c
>> b/drivers/gpu/drm/i915/intel_dsi.c
>> index 51a1d6868b1e..cf39ca90d887 100644
>> --- a/drivers/gpu/drm/i915/intel_dsi.c
>> +++ b/drivers/gpu/drm/i915/intel_dsi.c
>> @@ -1846,7 +1846,7 @@ void intel_dsi_init(struct drm_i915_private
>> *dev_priv)
>>      connector->display_info.width_mm = fixed_mode->width_mm;
>>      connector->display_info.height_mm = fixed_mode->height_mm;
>>  
>> -    intel_panel_init(&intel_connector->panel, fixed_mode, NULL,
>> NULL);
>> +    intel_panel_init(&intel_connector->panel, fixed_mode, NULL);
>>      intel_panel_setup_backlight(connector, INVALID_PIPE);
>>  
>>      intel_dsi_add_properties(intel_connector);
>> diff --git a/drivers/gpu/drm/i915/intel_dvo.c
>> b/drivers/gpu/drm/i915/intel_dvo.c
>> index eb0c559b2715..a70d767313aa 100644
>> --- a/drivers/gpu/drm/i915/intel_dvo.c
>> +++ b/drivers/gpu/drm/i915/intel_dvo.c
>> @@ -536,7 +536,7 @@ void intel_dvo_init(struct drm_i915_private
>> *dev_priv)
>>                       */
>>                      intel_panel_init(&intel_connector->panel,
>>                                       intel_dvo_get_current_mode(
>> intel_encoder),
>> -                                     NULL, NULL);
>> +                                     NULL);
>>                      intel_dvo->panel_wants_dither = true;
>>              }
>>  
>> diff --git a/drivers/gpu/drm/i915/intel_lvds.c
>> b/drivers/gpu/drm/i915/intel_lvds.c
>> index 8691c86f579c..d8ece907ff54 100644
>> --- a/drivers/gpu/drm/i915/intel_lvds.c
>> +++ b/drivers/gpu/drm/i915/intel_lvds.c
>> @@ -1140,8 +1140,7 @@ void intel_lvds_init(struct drm_i915_private
>> *dev_priv)
>>  out:
>>      mutex_unlock(&dev->mode_config.mutex);
>>  
>> -    intel_panel_init(&intel_connector->panel, fixed_mode, NULL,
>> -                     downclock_mode);
>> +    intel_panel_init(&intel_connector->panel, fixed_mode,
>> downclock_mode);
>>      intel_panel_setup_backlight(connector, INVALID_PIPE);
>>  
>>      lvds_encoder->is_dual_link =
>> compute_is_dual_link_lvds(lvds_encoder);
>> diff --git a/drivers/gpu/drm/i915/intel_panel.c
>> b/drivers/gpu/drm/i915/intel_panel.c
>> index 41d00b1603e3..b443278e569c 100644
>> --- a/drivers/gpu/drm/i915/intel_panel.c
>> +++ b/drivers/gpu/drm/i915/intel_panel.c
>> @@ -1928,13 +1928,11 @@ intel_panel_init_backlight_funcs(struct
>> intel_panel *panel)
>>  
>>  int intel_panel_init(struct intel_panel *panel,
>>                   struct drm_display_mode *fixed_mode,
>> -                 struct drm_display_mode *alt_fixed_mode,
>>                   struct drm_display_mode *downclock_mode)
>>  {
>>      intel_panel_init_backlight_funcs(panel);
>>  
>>      panel->fixed_mode = fixed_mode;
>> -    panel->alt_fixed_mode = alt_fixed_mode;
>>      panel->downclock_mode = downclock_mode;
>>  
>>      return 0;
>> @@ -1948,10 +1946,6 @@ void intel_panel_fini(struct intel_panel
>> *panel)
>>      if (panel->fixed_mode)
>>              drm_mode_destroy(intel_connector->base.dev, panel-
>> >fixed_mode);
>>  
>> -    if (panel->alt_fixed_mode)
>> -            drm_mode_destroy(intel_connector->base.dev,
>> -                            panel->alt_fixed_mode);
>> -
>>      if (panel->downclock_mode)
>>              drm_mode_destroy(intel_connector->base.dev,
>>                              panel->downclock_mode);

-- 
Jani Nikula, Intel Open Source Technology Center
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