[PATCH v2] drm/i915: Don't use the second dbuf slice on icl

[Ville Syrjala <ville.syrjala@linux.intel.com>]

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

The code managing the dbuf slices is borked and needs some
real work to fix. In the meantime let's just stop using the
second slice.

v2: Drop the change to intel_enabled_dbuf_slices_num() (Mahesh)

Cc: Mahesh Kumar <mahesh1.sh.kumar@gmail.com>
Reviewed-by: Imre Deak <imre.deak@intel.com> #v1
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/intel_pm.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 53b706154c94..ed9786241307 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3822,8 +3822,13 @@ static u16 intel_get_ddb_size(struct drm_i915_private *dev_priv,
 
 	/*
 	 * 12GB/s is maximum BW supported by single DBuf slice.
+	 *
+	 * FIXME dbuf slice code is broken:
+	 * - must wait for planes to stop using the slice before powering it off
+	 * - plane straddling both slices is illegal in multi-pipe scenarios
+	 * - should validate we stay within the hw bandwidth limits
 	 */
-	if (num_active > 1 || total_data_bw >= GBps(12)) {
+	if (0 && (num_active > 1 || total_data_bw >= GBps(12))) {
 		ddb->enabled_slices = 2;
 	} else {
 		ddb->enabled_slices = 1;
-- 
2.19.2

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