drm/i915/fbc: Make the cfb allocation loop a bit more legible

Write the cfb allocation loop as an actual loop instead of some
hard to read goto thing.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210610183237.3920-9-ville.syrjala@linux.intel.com
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>

diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c b/drivers/gpu/drm/i915/display/intel_fbc.c
index 6415f2c..b6bfb44 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_fbc.c
+++ b/drivers/gpu/drm/i915/display/intel_fbc.c
@@ -440,44 +440,45 @@ static u64 intel_fbc_stolen_end(struct drm_i915_private *dev_priv)
        return min(end, intel_fbc_cfb_base_max(dev_priv));
 }
 
+static int intel_fbc_max_limit(struct drm_i915_private *dev_priv, int fb_cpp)
+{
+       /*
+        * FIXME: FBC1 can have arbitrary cfb stride,
+        * so we could support different compression ratios.
+        */
+       if (DISPLAY_VER(dev_priv) < 5 && !IS_G4X(dev_priv))
+               return 1;
+
+       /* WaFbcOnly1to1Ratio:ctg */
+       if (IS_G4X(dev_priv))
+               return 1;
+
+       /* FBC2 can only do 1:1, 1:2, 1:4 */
+       return fb_cpp == 2 ? 2 : 4;
+}
+
 static int find_compression_limit(struct drm_i915_private *dev_priv,
                                  unsigned int size,
                                  unsigned int fb_cpp)
 {
        struct intel_fbc *fbc = &dev_priv->fbc;
        u64 end = intel_fbc_stolen_end(dev_priv);
-       int compression_limit = 1;
-       int ret;
-
-       /* HACK: This code depends on what we will do in *_enable_fbc. If that
-        * code changes, this code needs to change as well.
-        *
-        * The enable_fbc code will attempt to use one of our 2 compression
-        * limits, therefore, in that case, we only have 1 resort.
-        */
+       int ret, limit = 1;
 
        /* Try to over-allocate to reduce reallocations and fragmentation. */
        ret = i915_gem_stolen_insert_node_in_range(dev_priv, &fbc->compressed_fb,
                                                   size <<= 1, 4096, 0, end);
        if (ret == 0)
-               return compression_limit;
-
-again:
-       /* HW's ability to limit the CFB is 1:4 */
-       if (compression_limit > 4 ||
-           (fb_cpp == 2 && compression_limit == 2))
-               return 0;
+               return limit;
 
-       ret = i915_gem_stolen_insert_node_in_range(dev_priv, &fbc->compressed_fb,
-                                                  size >>= 1, 4096, 0, end);
-       if (ret && DISPLAY_VER(dev_priv) <= 4) {
-               return 0;
-       } else if (ret) {
-               compression_limit <<= 1;
-               goto again;
-       } else {
-               return compression_limit;
+       for (; limit <= intel_fbc_max_limit(dev_priv, fb_cpp); limit <<= 1) {
+               ret = i915_gem_stolen_insert_node_in_range(dev_priv, &fbc->compressed_fb,
+                                                          size >>= 1, 4096, 0, end);
+               if (ret == 0)
+                       return limit;
        }
+
+       return 0;
 }
 
 static int intel_fbc_alloc_cfb(struct drm_i915_private *dev_priv,