diff --git a/plat/arm/css/common/css_topology.c b/plat/arm/css/common/css_topology.c
index bccf2c8..42f9455 100644
--- a/plat/arm/css/common/css_topology.c
+++ b/plat/arm/css/common/css_topology.c
@@ -6,6 +6,7 @@
 
 #include <plat_arm.h>
 #include <platform.h>
+#include <assert.h>
 
 #if ARM_PLAT_MT
 #pragma weak plat_arm_get_cpu_pe_count
@@ -19,9 +20,12 @@
  *****************************************************************************/
 int plat_core_pos_by_mpidr(u_register_t mpidr)
 {
-	if (arm_check_mpidr(mpidr) == 0)
+	if (arm_check_mpidr(mpidr) == 0) {
+#if ARM_PLAT_MT
+		assert((read_mpidr_el1() & MPIDR_MT_MASK) != 0);
+#endif
 		return plat_arm_calc_core_pos(mpidr);
-
+	}
 	return -1;
 }
 
diff --git a/plat/arm/css/sgi/aarch64/sgi_helper.S b/plat/arm/css/sgi/aarch64/sgi_helper.S
index c435d8b..aaa5156 100644
--- a/plat/arm/css/sgi/aarch64/sgi_helper.S
+++ b/plat/arm/css/sgi/aarch64/sgi_helper.S
@@ -31,19 +31,37 @@
 endfunc plat_is_my_cpu_primary
 
 	/* -----------------------------------------------------
-	*  unsigned int plat_arm_calc_core_pos(uint64_t mpidr)
-	*  Helper function to calculate the core position.
-	* -----------------------------------------------------
-	*/
+	 * unsigned int plat_arm_calc_core_pos(u_register_t mpidr)
+	 *
+	 * Helper function to calculate the core position.
+	 * (ClusterId * CSS_SGI_MAX_CPUS_PER_CLUSTER * CSS_SGI_MAX_PE_PER_CPU) +
+	 * (CPUId * CSS_SGI_MAX_PE_PER_CPU) +
+	 * ThreadId
+	 *
+	 * which can be simplified as:
+	 *
+	 * ((ClusterId * CSS_SGI_MAX_CPUS_PER_CLUSTER + CPUId) *
+	 * CSS_SGI_MAX_PE_PER_CPU) + ThreadId
+	 * ------------------------------------------------------
+	 */
+
 func plat_arm_calc_core_pos
-	mrs     x2, mpidr_el1
-	ands    x2, x2, #MPIDR_MT_MASK
-	beq     1f
-	lsr     x0, x0, #MPIDR_AFF1_SHIFT
-1:
-	and	x1, x0, #MPIDR_CPU_MASK
-	and	x0, x0, #MPIDR_CLUSTER_MASK
-	add	x0, x1, x0, LSR #6
-	and     x0, x0, #MPIDR_AFFLVL_MASK
+	mov	x3, x0
+
+	/*
+	 * The MT bit in MPIDR is always set for SGI platforms
+	 * and the affinity level 0 corresponds to thread affinity level.
+	 */
+
+	/* Extract individual affinity fields from MPIDR */
+	ubfx    x0, x3, #MPIDR_AFF0_SHIFT, #MPIDR_AFFINITY_BITS
+	ubfx    x1, x3, #MPIDR_AFF1_SHIFT, #MPIDR_AFFINITY_BITS
+	ubfx    x2, x3, #MPIDR_AFF2_SHIFT, #MPIDR_AFFINITY_BITS
+
+	/* Compute linear position */
+	mov     x4, #CSS_SGI_MAX_CPUS_PER_CLUSTER
+	madd    x1, x2, x4, x1
+	mov     x5, #CSS_SGI_MAX_PE_PER_CPU
+	madd    x0, x1, x5, x0
 	ret
 endfunc plat_arm_calc_core_pos
diff --git a/plat/arm/css/sgi/include/platform_def.h b/plat/arm/css/sgi/include/platform_def.h
index 62f4059..94d4ff9 100644
--- a/plat/arm/css/sgi/include/platform_def.h
+++ b/plat/arm/css/sgi/include/platform_def.h
@@ -14,12 +14,14 @@
 #include <css_def.h>
 #include <soc_css_def.h>
 
-#define CSS_SGI_MAX_CORES_PER_CLUSTER	4
+#define CSS_SGI_MAX_CPUS_PER_CLUSTER	4
 
 /* CPU topology */
 #define PLAT_ARM_CLUSTER_COUNT		2
+#define CSS_SGI_MAX_PE_PER_CPU		1
 #define PLATFORM_CORE_COUNT		(PLAT_ARM_CLUSTER_COUNT *	\
-					CSS_SGI_MAX_CORES_PER_CLUSTER)
+					CSS_SGI_MAX_CPUS_PER_CLUSTER * \
+					CSS_SGI_MAX_PE_PER_CPU)
 
 #if ARM_BOARD_OPTIMISE_MEM
 
diff --git a/plat/arm/css/sgi/sgi_topology.c b/plat/arm/css/sgi/sgi_topology.c
index 2136591..1d2e027 100644
--- a/plat/arm/css/sgi/sgi_topology.c
+++ b/plat/arm/css/sgi/sgi_topology.c
@@ -16,14 +16,14 @@
  */
 const unsigned char sgi_pd_tree_desc[] = {
 	PLAT_ARM_CLUSTER_COUNT,
-	CSS_SGI_MAX_CORES_PER_CLUSTER,
-	CSS_SGI_MAX_CORES_PER_CLUSTER
+	CSS_SGI_MAX_CPUS_PER_CLUSTER,
+	CSS_SGI_MAX_CPUS_PER_CLUSTER
 };
 
 /* Topology configuration for sgi platform */
 const css_topology_t sgi_topology = {
 	.power_tree = sgi_pd_tree_desc,
-	.plat_cluster_core_count = CSS_SGI_MAX_CORES_PER_CLUSTER
+	.plat_cluster_core_count = CSS_SGI_MAX_CPUS_PER_CLUSTER
 };
 
 /*******************************************************************************