drm/msm/a6xx: Skip empty protection ranges entries

Some specific SKUs leave certain protection range registers empty.
Allow for that behavior.
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/543334/Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/adreno/a6xx_gpu.c

@@ -935,8 +935,11 @@ static void a6xx_set_cp_protect(struct msm_gpu *gpu)
 		  A6XX_CP_PROTECT_CNTL_ACCESS_FAULT_ON_VIOL_EN |
 		  A6XX_CP_PROTECT_CNTL_LAST_SPAN_INF_RANGE);
 
-	for (i = 0; i < count - 1; i++)
-		gpu_write(gpu, REG_A6XX_CP_PROTECT(i), regs[i]);
+	for (i = 0; i < count - 1; i++) {
+		/* Intentionally skip writing to some registers */
+		if (regs[i])
+			gpu_write(gpu, REG_A6XX_CP_PROTECT(i), regs[i]);
+	}
 	/* last CP_PROTECT to have "infinite" length on the last entry */
 	gpu_write(gpu, REG_A6XX_CP_PROTECT(count_max - 1), regs[i]);
 }