drm/i915: Pretend cursor is always on for ILK-style WM calculations (v2)

Due to our lack of two-step watermark programming, our driver has
historically pretended that the cursor plane is always on for the
purpose of watermark calculations; this helps avoid serious flickering
when the cursor turns off/on (e.g., when the user moves the mouse
pointer to a different screen).  That workaround was accidentally
dropped as we started working toward atomic watermark updates.  Since we
still aren't quite there yet with two-stage updates, we need to
resurrect the workaround and treat the cursor as always active.

v2: Tweak cursor width calculations slightly to more closely match the
    logic we used before the atomic overhaul began.  (Ville)

Cc: simdev11@outlook.com
Cc: manfred.kitzbichler@gmail.com
Cc: drm-intel-fixes@lists.freedesktop.org
Reported-by: simdev11@outlook.com
Reported-by: manfred.kitzbichler@gmail.com
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93892
Fixes: 43d59eda1 ("drm/i915: Eliminate usage of plane_wm_parameters from ILK-style WM code (v2)")
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1454479611-6804-1-git-send-email-matthew.d.roper@intel.com

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index a47b8f219357c3dd6efbba5773757457a97a1c18..3da7935c166537c30e78376ca408155421b3cd6d 100644 (file)
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -1799,16 +1799,20 @@ static uint32_t ilk_compute_cur_wm(const struct intel_crtc_state *cstate,
                                   const struct intel_plane_state *pstate,
                                   uint32_t mem_value)
 {
-       int cpp = pstate->base.fb ?
-               drm_format_plane_cpp(pstate->base.fb->pixel_format, 0) : 0;
+       /*
+        * We treat the cursor plane as always-on for the purposes of watermark
+        * calculation.  Until we have two-stage watermark programming merged,
+        * this is necessary to avoid flickering.
+        */
+       int cpp = 4;
+       int width = pstate->visible ? pstate->base.crtc_w : 64;
 
-       if (!cstate->base.active || !pstate->visible)
+       if (!cstate->base.active)
                return 0;
 
        return ilk_wm_method2(ilk_pipe_pixel_rate(cstate),
                              cstate->base.adjusted_mode.crtc_htotal,
-                             drm_rect_width(&pstate->dst),
-                             cpp, mem_value);
+                             width, cpp, mem_value);
 }
 
 /* Only for WM_LP. */