diff --git a/ggml/src/ggml-metal/ggml-metal.metal b/ggml/src/ggml-metal/ggml-metal.metal
index 8d6e99e62..9f4147e93 100644
--- a/ggml/src/ggml-metal/ggml-metal.metal
+++ b/ggml/src/ggml-metal/ggml-metal.metal
@@ -3192,7 +3192,7 @@ kernel void kernel_flash_attn_ext(
 
     {
         float S[Q] = { [0 ... Q-1] = 0.0f };
-        float M[Q] = { [0 ... Q-1] = -__FLT16_MAX__/2 };
+        float M[Q] = { [0 ... Q-1] = -__FLT_MAX__/2 };
 
         // thread indices inside the simdgroup
         // TODO: see if we can utilize quad-group functions for better performance
@@ -3452,7 +3452,7 @@ kernel void kernel_flash_attn_ext(
     // reduce the warps sequentially
     for (ushort sg = 1; sg < nsg; ++sg) {
         float S = { 0.0f };
-        float M = { -__FLT16_MAX__/2 };
+        float M = { -__FLT_MAX__/2 };
 
         threadgroup_barrier(mem_flags::mem_threadgroup);
 
@@ -3699,7 +3699,7 @@ kernel void kernel_flash_attn_ext_vec(
 
     {
         float S = 0.0f;
-        float M = -__FLT16_MAX__/2;
+        float M = -__FLT_MAX__/2;
 
         // thread indices inside the simdgroup
         const short tx = tiisg%NL;
diff --git a/ggml/src/ggml-vulkan/ggml-vulkan.cpp b/ggml/src/ggml-vulkan/ggml-vulkan.cpp
index 1e311da73..89dc4242f 100644
--- a/ggml/src/ggml-vulkan/ggml-vulkan.cpp
+++ b/ggml/src/ggml-vulkan/ggml-vulkan.cpp
@@ -262,6 +262,7 @@ struct vk_device_struct {
     bool pipeline_robustness;
     vk::Device device;
     uint32_t vendor_id;
+    vk::DriverId driver_id;
     vk_device_architecture architecture;
     vk_queue compute_queue;
     vk_queue transfer_queue;
@@ -1756,6 +1757,11 @@ static void ggml_vk_load_shaders(vk_device& device) {
         m_warptile_mmq_int = { 128,  64,  64, 32, subgroup_size_8,     32, 2, 2, 2, 1, subgroup_size_8 };
         s_warptile_mmq_int = { subgroup_size_32, 32, 32, 32, 32,       32, 2, 2, 1, 1, subgroup_size_8 };
 
+        // chip specific tuning
+        if ((device->architecture == AMD_GCN) && (device->driver_id != vk::DriverId::eAmdProprietary)) {
+            m_warptile_mmq = m_warptile_mmq_int = { 256, 64, 64, 32, 16, 16, 2, 2, 2, 1, 16 };
+        }
+
         l_mmq_wg_denoms = l_wg_denoms = {128, 128, 1 };
         m_mmq_wg_denoms = m_wg_denoms = { 64,  64, 1 };
         s_mmq_wg_denoms = s_wg_denoms = { 32,  32, 1 };
@@ -2678,6 +2684,7 @@ static vk_device ggml_vk_get_device(size_t idx) {
         device->physical_device.getProperties2(&props2);
         device->properties = props2.properties;
         device->vendor_id = device->properties.vendorID;
+        device->driver_id = driver_props.driverID;
 
         const char* GGML_VK_FORCE_MAX_ALLOCATION_SIZE = getenv("GGML_VK_FORCE_MAX_ALLOCATION_SIZE");