Commit 4ffac6f0 authored by Paulo Zanoni's avatar Paulo Zanoni Committed by Greg Kroah-Hartman

drm/i915/gen9: fix the WM memory bandwidth WA for Y tiling cases

commit 2ef32dee upstream.

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: ee3d532f ("drm/i915/gen9: unconditionally apply the memory bandwidth WA")
Cc: stable@vger.kernel.org
Cc: Mahesh Kumar <mahesh1.kumar@intel.com>
Signed-off-by: default avatarPaulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: default avatarMatt Roper <matthew.d.roper@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1478636531-6081-1-git-send-email-paulo.r.zanoni@intel.comSigned-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent f482823e
......@@ -3617,6 +3617,9 @@ 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) {
......@@ -3637,8 +3640,6 @@ 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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