drm/i915: Fix fractional bpp handling in intel_link_bw_reduce_bpp()

Convert crtc_state->pipe_bpp to U6.4 format as expected by the rest of
the function.

Fixes: 59a266f0 ("drm/i915/display: Store compressed bpp in U6.4 format")
Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Cc: Suraj Kandpal <suraj.kandpal@intel.com>
Cc: Sui Jingfeng <suijingfeng@loongson.cn>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231114141012.603960-1-imre.deak@intel.com

drivers/gpu/drm/i915/display/intel_link_bw.c

@@ -55,11 +55,11 @@ int intel_link_bw_reduce_bpp(struct intel_atomic_state *state,
 	struct drm_i915_private *i915 = to_i915(state->base.dev);
 	enum pipe max_bpp_pipe = INVALID_PIPE;
 	struct intel_crtc *crtc;
-	int max_bpp = 0;
+	int max_bpp_x16 = 0;
 
 	for_each_intel_crtc_in_pipe_mask(&i915->drm, crtc, pipe_mask) {
 		struct intel_crtc_state *crtc_state;
-		int link_bpp;
+		int link_bpp_x16;
 
 		if (limits->bpp_limit_reached_pipes & BIT(crtc->pipe))
 			continue;
@@ -70,7 +70,7 @@ int intel_link_bw_reduce_bpp(struct intel_atomic_state *state,
 			return PTR_ERR(crtc_state);
 
 		if (crtc_state->dsc.compression_enable)
-			link_bpp = crtc_state->dsc.compressed_bpp_x16;
+			link_bpp_x16 = crtc_state->dsc.compressed_bpp_x16;
 		else
 			/*
 			 * TODO: for YUV420 the actual link bpp is only half
@@ -78,10 +78,10 @@ int intel_link_bw_reduce_bpp(struct intel_atomic_state *state,
 			 * is based on the pipe bpp value, set the actual link bpp
 			 * limit here once the MST BW allocation is fixed.
 			 */
-			link_bpp = crtc_state->pipe_bpp;
+			link_bpp_x16 = to_bpp_x16(crtc_state->pipe_bpp);
 
-		if (link_bpp > max_bpp) {
-			max_bpp = link_bpp;
+		if (link_bpp_x16 > max_bpp_x16) {
+			max_bpp_x16 = link_bpp_x16;
 			max_bpp_pipe = crtc->pipe;
 		}
 	}
@@ -89,7 +89,7 @@ int intel_link_bw_reduce_bpp(struct intel_atomic_state *state,
 	if (max_bpp_pipe == INVALID_PIPE)
 		return -ENOSPC;
 
-	limits->max_bpp_x16[max_bpp_pipe] = to_bpp_x16(max_bpp) - 1;
+	limits->max_bpp_x16[max_bpp_pipe] = max_bpp_x16 - 1;
 
 	return intel_modeset_pipes_in_mask_early(state, reason,
 						 BIT(max_bpp_pipe));