The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 2ef32dee97fcf41987722a37eb6ff1a983915e99 Mon Sep 17 00:00:00 2001
From: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx>
Date: Tue, 8 Nov 2016 18:22:11 -0200
Subject: [PATCH] drm/i915/gen9: fix the WM memory bandwidth WA for Y tiling
cases
The previous spec version said "double Ytile planes minimum lines",
and I interpreted this as referring to what the spec calls "Y tile
minimum", but in fact it was referring to what the spec calls "Minimum
Scanlines for Y tile". I noticed that Mahesh Kumar had a different
interpretation, so I sent and email to the spec authors and got
clarification on the correct meaning. Also, BSpec was updated and
should be clear now.
Fixes: ee3d532fcb64 ("drm/i915/gen9: unconditionally apply the memory bandwidth WA")
Cc: stable@xxxxxxxxxxxxxxx
Cc: Mahesh Kumar <mahesh1.kumar@xxxxxxxxx>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx>
Reviewed-by: Matt Roper <matthew.d.roper@xxxxxxxxx>
Link: http://patchwork.freedesktop.org/patch/msgid/1478636531-6081-1-git-send-email-paulo.r.zanoni@xxxxxxxxx
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 35c4afd2e143..f1ef9559014c 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3626,6 +3626,9 @@ static int skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
y_min_scanlines = 4;
}
+ if (apply_memory_bw_wa)
+ y_min_scanlines *= 2;
+
plane_bytes_per_line = width * cpp;
if (fb->modifier[0] == I915_FORMAT_MOD_Y_TILED ||
fb->modifier[0] == I915_FORMAT_MOD_Yf_TILED) {
@@ -3646,8 +3649,6 @@ static int skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
plane_blocks_per_line);
y_tile_minimum = plane_blocks_per_line * y_min_scanlines;
- if (apply_memory_bw_wa)
- y_tile_minimum *= 2;
if (fb->modifier[0] == I915_FORMAT_MOD_Y_TILED ||
fb->modifier[0] == I915_FORMAT_MOD_Yf_TILED) {
--
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