Patch "drm/i915: Pretend cursor is always on for ILK-style WM calculations (v2)" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

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

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
drm-i915-pretend-cursor-is-always-on-for-ilk-style-wm-calculations-v2.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Matt Roper <[email protected]>
Date: Mon, 8 Feb 2016 11:05:28 -0800
Subject: drm/i915: Pretend cursor is always on for ILK-style WM calculations (v2)

From: Matt Roper <[email protected]>

commit e2e407dc093f530b771ee8bf8fe1be41e3cea8b3 upstream.

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)

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93892

---
 drivers/gpu/drm/i915/intel_pm.c |   14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

@@ -1789,16 +1789,20 @@ static uint32_t ilk_compute_cur_wm(const
 				   const struct intel_plane_state *pstate,
 				   uint32_t mem_value)
 {
-	int bpp = pstate->base.fb ? pstate->base.fb->bits_per_pixel / 8 : 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),
-			      bpp,
-			      mem_value);
+			      width, cpp, mem_value);
 }
 
 /* Only for WM_LP. */

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/drm-i915-pretend-cursor-is-always-on-for-ilk-style-wm-calculations-v2.patch