drm/i915: enable the pipe/transcoder/planes later on HSW+

For all platforms that run haswell_crtc_enable, our spec tells us to
configure the transcoder clocks and do link training before it tells
us to set pipeconf and the other pipe/transcoder/plane registers.

Starting from Icelake, we get machine hangs if we try to touch the
pipe/transcoder registers without having the clocks configured and not
having some chicken bits set. So this patch changes
haswell_crtc_enable() to issue the calls at the appropriate order
mandated by the spec.

While setting the appropriate chicken bits would also work here, it's
better if we actually program the hardware the way it is intended to
be programmed. And the chicken bit also has some theoretical downsides
that may or may not affect us. Also, correctly programming the
hardware does not prevent us from setting the chicken bits in a later
patch in case we decide to.

v2: Don't forget link training (Ville).

Cc: Arthur J Runyan <arthur.j.runyan@intel.com>
Cc: James Ausmus <james.ausmus@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180502215851.30736-1-paulo.r.zanoni@intel.com

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 817d5d3f65ebe9d415663676dca3c7c19b48ed25..c9ec88acad9c16ed0fb823511ad195b934d03a2c 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5581,6 +5581,11 @@ static void haswell_crtc_enable(struct intel_crtc_state *pipe_config,
        if (INTEL_GEN(dev_priv) >= 11)
                icl_map_plls_to_ports(crtc, pipe_config, old_state);
 
+       intel_encoders_pre_enable(crtc, pipe_config, old_state);
+
+       if (!transcoder_is_dsi(cpu_transcoder))
+               intel_ddi_enable_pipe_clock(pipe_config);
+
        if (intel_crtc_has_dp_encoder(intel_crtc->config))
                intel_dp_set_m_n(intel_crtc, M1_N1);
 
@@ -5609,11 +5614,6 @@ static void haswell_crtc_enable(struct intel_crtc_state *pipe_config,
 
        intel_crtc->active = true;
 
-       intel_encoders_pre_enable(crtc, pipe_config, old_state);
-
-       if (!transcoder_is_dsi(cpu_transcoder))
-               intel_ddi_enable_pipe_clock(pipe_config);
-
        /* Display WA #1180: WaDisableScalarClockGating: glk, cnl */
        psl_clkgate_wa = (IS_GEMINILAKE(dev_priv) || IS_CANNONLAKE(dev_priv)) &&
                         intel_crtc->config->pch_pfit.enabled;