Quoting Maarten Lankhorst (2018-03-13 09:28:55)
On fi-cnl-y3 we have 2 modes that differ only by crtc_clock. This means that if we request the normal mode, we automatically get the downclocked mode.
This can be seen during boot: [drm:drm_helper_probe_single_connector_modes] [CONNECTOR:101:eDP-1] probed modes : [drm:drm_mode_debug_printmodeline] Modeline 102:"3840x2160" 60 533250 3840 3888 3920 4000 2160 2163 2168 2222 0x48 0xa [drm:drm_mode_debug_printmodeline] Modeline 103:"3840x2160" 48 426600 3840 3888 3920 4000 2160 2163 2168 2222 0x40 0xa ... [drm:intel_dump_pipe_config [i915]] [CRTC:51:pipe A][modeset] [drm:intel_dump_pipe_config [i915]] output_types: EDP (0x100) [drm:intel_dump_pipe_config [i915]] cpu_transcoder: EDP, pipe bpp: 24, dithering: 0 [drm:intel_dump_pipe_config [i915]] dp m_n: lanes: 4; gmch_m: 4970250, gmch_n: 8388608, link_m: 828375, link_n: 1048576, tu: 64 [drm:intel_dump_pipe_config [i915]] dp m2_n2: lanes: 4; gmch_m: 4970250, gmch_n: 8388608, link_m: 828375, link_n: 1048576, tu: 64 [drm:intel_dump_pipe_config [i915]] audio: 0, infoframes: 0 [drm:intel_dump_pipe_config [i915]] requested mode: [drm:drm_mode_debug_printmodeline] Modeline 0:"3840x2160" 60 533250 3840 3888 3920 4000 2160 2163 2168 2222 0x48 0xa [drm:intel_dump_pipe_config [i915]] adjusted mode: [drm:drm_mode_debug_printmodeline] Modeline 0:"3840x2160" 48 426600 3840 3888 3920 4000 2160 2163 2168 2222 0x40 0xa
Testcase: kms_panel_fitting.atomic-fastset Signed-off-by: Maarten Lankhorst maarten.lankhorst@linux.intel.com Fixes: dc911f5bd8aa ("drm/i915/edp: Allow alternate fixed mode for eDP if available.") Cc: David Weinehall david.weinehall@linux.intel.com Cc: Rodrigo Vivi rodrigo.vivi@intel.com Cc: Paulo Zanoni paulo.r.zanoni@intel.com Cc: Jani Nikula jani.nikula@intel.com Cc: Chris Wilson chris@chris-wilson.co.uk Cc: Jim Bride jim.bride@linux.intel.com Cc: Joonas Lahtinen joonas.lahtinen@linux.intel.com Cc: stable@vger.kernel.org # v4.14+
drivers/gpu/drm/i915/intel_dp.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 9a4a51e79fa1..0bd3cc1c82b4 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -1684,7 +1684,8 @@ static bool intel_edp_compare_alt_mode(struct drm_display_mode *m1, m1->vdisplay == m2->vdisplay && m1->vsync_start == m2->vsync_start && m1->vsync_end == m2->vsync_end &&
m1->vtotal == m2->vtotal);
m1->vtotal == m2->vtotal &&m1->clock == m2->clock);
Should it be exact on clock or just closer to alt-clock than preferred-clock? -Chris