[Intel-gfx] [PATCH] drm/i915: Check if WM is greater than previous level

[Mustamin B Mustaffa]

From: "Kumar, Mahesh" <mahesh1.ku...@intel.com>

Some time WM calculated values are higher for lower level & lower WM
value for higher level. This leads to allocation of less DDB to plane &
may result in disabling lower WM level but enabling higher WM level.
which may lead to under run.

This patch make sure that higher watermark levels doesn't have WM value
less than lower levels.

Signed-off-by: Kumar, Mahesh <mahesh1.ku...@intel.com>
---
 drivers/gpu/drm/i915/intel_pm.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index de678ae..c2ae65d 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3797,8 +3797,7 @@ static int skl_compute_plane_wm(const struct 
drm_i915_private *dev_priv,
                                struct intel_crtc_state *cstate,
                                const struct intel_plane_state *intel_pstate,
                                int level,
-                               uint16_t *out_blocks, /* out */
-                               uint8_t *out_lines /* out */)
+                               struct skl_plane_wm *wm /* out */)
 {
        struct intel_plane *plane = to_intel_plane(intel_pstate->base.plane);
        const struct drm_plane_state *pstate = &intel_pstate->base;
@@ -3819,6 +3818,8 @@ static int skl_compute_plane_wm(const struct 
drm_i915_private *dev_priv,
                to_intel_atomic_state(cstate->base.state);
        bool apply_memory_bw_wa = skl_needs_memory_bw_wa(state);
        bool y_tiled, x_tiled;
+       uint16_t *out_blocks = &wm->wm[level].plane_res_b;
+       uint8_t *out_lines = &wm->wm[level].plane_res_l;
 
        if (latency == 0 ||
            !intel_wm_plane_visible(cstate, intel_pstate))
@@ -3927,6 +3928,11 @@ static int skl_compute_plane_wm(const struct 
drm_i915_private *dev_priv,
                }
        }
 
+       if ((level > 0) && (res_blocks < wm->wm[level - 1].plane_res_b)) {
+                       res_blocks = wm->wm[level - 1].plane_res_b;
+                       res_lines = wm->wm[level - 1].plane_res_l;
+       }
+
        if (res_lines >= 31 && level == 0) {
                struct drm_plane *plane = pstate->plane;
 
@@ -3954,14 +3960,13 @@ skl_compute_wm_level(const struct drm_i915_private 
*dev_priv,
                return -EINVAL;
 
        for (level = 0; level <= max_level; level++) {
-               struct skl_wm_level *result = &wm->wm[level];
 
                ret = skl_compute_plane_wm(dev_priv,
                                           cstate,
                                           intel_pstate,
                                           level,
-                                          &result->plane_res_b,
-                                          &result->plane_res_l);
+                                          wm);
+
                if (ret)
                        return ret;
        }
-- 
1.9.1

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