drm/i915: Check pipe source size when using skl+ scalers

[ Upstream commit d944eafed618a8507270b324ad9d5405bb7f0b3e ]

The skl+ scalers only sample 12 bits of PIPESRC so we can't
do any plane scaling at all when the pipe source size is >4k.

Make sure the pipe source size is also below the scaler's src
size limits. Might not be 100% accurate, but should at least be
safe. We can refine the limits later if we discover that recent
hw is less restricted.

Cc: stable@vger.kernel.org
Tested-by: Ross Zwisler <zwisler@google.com>
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/8357
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230418175528.13117-2-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
(cherry picked from commit 691248d4135fe3fae64b4ee0676bc96a7fd6950c)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/i915/display/skl_scaler.c b/drivers/gpu/drm/i915/display/skl_scaler.c
index e6ec5ed0d00ec464dc4ffdaed81e3ecb1e1defe9..90f42f63128ec24a82fdb16e81b35c26c5834191 100644 (file)
--- a/drivers/gpu/drm/i915/display/skl_scaler.c
+++ b/drivers/gpu/drm/i915/display/skl_scaler.c
@@ -105,6 +105,8 @@ skl_update_scaler(struct intel_crtc_state *crtc_state, bool force_detach,
        struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
        const struct drm_display_mode *adjusted_mode =
                &crtc_state->hw.adjusted_mode;
+       int pipe_src_w = drm_rect_width(&crtc_state->pipe_src);
+       int pipe_src_h = drm_rect_height(&crtc_state->pipe_src);
        int min_src_w, min_src_h, min_dst_w, min_dst_h;
        int max_src_w, max_src_h, max_dst_w, max_dst_h;
 
@@ -196,6 +198,21 @@ skl_update_scaler(struct intel_crtc_state *crtc_state, bool force_detach,
                return -EINVAL;
        }
 
+       /*
+        * The pipe scaler does not use all the bits of PIPESRC, at least
+        * on the earlier platforms. So even when we're scaling a plane
+        * the *pipe* source size must not be too large. For simplicity
+        * we assume the limits match the scaler source size limits. Might
+        * not be 100% accurate on all platforms, but good enough for now.
+        */
+       if (pipe_src_w > max_src_w || pipe_src_h > max_src_h) {
+               drm_dbg_kms(&dev_priv->drm,
+                           "scaler_user index %u.%u: pipe src size %ux%u "
+                           "is out of scaler range\n",
+                           crtc->pipe, scaler_user, pipe_src_w, pipe_src_h);
+               return -EINVAL;
+       }
+
        /* mark this plane as a scaler user in crtc_state */
        scaler_state->scaler_users |= (1 << scaler_user);
        drm_dbg_kms(&dev_priv->drm, "scaler_user index %u.%u: "