[PATCH 7/8] drm/i915: Bump fb stride limit to 128KiB for gen4+ and 256KiB for gen7+

Timo Aaltonen tjaalton at ubuntu.com
Wed Aug 14 14:42:54 UTC 2019

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

BugLink: http://bugs.launchpad.net/bugs/1714178

With gtt remapping plugged in we can simply raise the stride
limit on gen4+. Let's just pick the limit to match the render
engine max stride (256KiB on gen7+, 128KiB on gen4+).

No remapping CCS because the virtual address of each page actually
matters due to the new hash mode
(WaCompressedResourceDisplayNewHashMode:skl,kbl etc.), and no
remapping on gen2/3 due extra complications from fence alignment
and gen2 2KiB GTT tile size. Also no real benefit since the
display engine limits already match the other limits.

v2: Rebase due to is_ccs_modifier()
v3: Tweak the comment and commit msg
v4: Fix gen4+ stride limit to be 128KiB

Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch> #v3
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190509122159.24376-8-ville.syrjala@linux.intel.com
Reviewed-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
(cherry picked from commit 2033012982231533e545b002f744a60699fe968c)
Signed-off-by: Timo Aaltonen <timo.aaltonen at canonical.com>
 drivers/gpu/drm/i915/intel_display.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 5fcb50dc29c7..89196b876037 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2480,6 +2480,19 @@ static
 u32 intel_fb_max_stride(struct drm_i915_private *dev_priv,
 			u32 pixel_format, u64 modifier)
+	/*
+	 * Arbitrary limit for gen4+ chosen to match the
+	 * render engine max stride.
+	 *
+	 * The new CCS hash mode makes remapping impossible
+	 */
+	if (!is_ccs_modifier(modifier)) {
+		if (INTEL_GEN(dev_priv) >= 7)
+			return 256*1024;
+		else if (INTEL_GEN(dev_priv) >= 4)
+			return 128*1024;
+	}
 	return intel_plane_fb_max_stride(dev_priv, pixel_format, modifier);

More information about the kernel-team mailing list