intel: EU/subslice runtime detection via GT_SLICE_INFO and EU_DISABLE fuses

local/recipes/gpu/redox-drm/source/src/drivers/intel/info.rs

@@ -1,6 +1,13 @@
 use log::warn;
 
 const GMD_ID_MMIO: usize = 0x138040;
+const GEN8_EU_DISABLE0: usize = 0x1913C;
+const GEN8_EU_DISABLE1: usize = 0x19140;
+const GEN8_EU_DISABLE2: usize = 0x19144;
+const GEN8_GT_SLICE_INFO: usize = 0x138064;
+const GEN8_GT_SUBSLICE_MASK_SHIFT: u32 = 8;
+const GEN8_GT_EUS_PER_SUBSLICE_SHIFT: u32 = 0;
+const GEN8_GT_EUS_PER_SUBSLICE_MASK: u32 = 0xFF;
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub struct GmdId {
@@ -255,3 +262,24 @@ pub fn device_info_from_id(device_id: u16) -> IntelDeviceInfo {
     warn!("redox-drm: Intel device {:#06x} not in device info table — using Gen9 defaults", device_id);
     default_info()
 }
+
+pub fn detect_eu_config(mmio: &redox_driver_sys::memory::MmioRegion) -> (u8, u8) {
+    let gt_info = mmio.read32(GEN8_GT_SLICE_INFO);
+    let eus_per_subslice = ((gt_info >> GEN8_GT_EUS_PER_SUBSLICE_SHIFT as u32)
+        & GEN8_GT_EUS_PER_SUBSLICE_MASK) as u8;
+    let subslice_count = ((gt_info >> GEN8_GT_SUBSLICE_MASK_SHIFT as u32) & 0xFF) as u8;
+
+    let total_eus = if eus_per_subslice > 0 && subslice_count > 0 {
+        eus_per_subslice.saturating_mul(subslice_count)
+    } else {
+        let disabled0 = !mmio.read32(GEN8_EU_DISABLE0);
+        let disabled1 = !mmio.read32(GEN8_EU_DISABLE1);
+        let disabled2 = !mmio.read32(GEN8_EU_DISABLE2);
+        let enabled = (disabled0.count_ones()
+            + disabled1.count_ones()
+            + disabled2.count_ones()) as u8;
+        enabled
+    };
+
+    (total_eus, subslice_count)
+}

local/recipes/gpu/redox-drm/source/src/drivers/intel/mod.rs

@@ -71,7 +71,7 @@ use self::gt::IntelGtManager;
 use self::gtt::IntelGtt;
 use self::guc::GucFirmware;
 use self::hotplug::HotplugHandler;
-use self::info::{GmdId, IntelDeviceInfo, IntelGeneration, device_info_from_id};
+use self::info::{GmdId, IntelDeviceInfo, IntelGeneration, detect_eu_config, device_info_from_id};
 use self::lmem::{IntelLmem, is_discrete_gpu};
 use self::regs::IntelRegs;
 use self::regs_gen9::Gen9Regs;
@@ -215,6 +215,16 @@ impl IntelDriver {
             info!("redox-drm-intel: no GMD_ID available (stepping {}), using static device info", stepping);
         }
 
+        let (eu_count, subslice_count) = detect_eu_config(&mmio_arc);
+        if eu_count > 0 {
+            device_info.num_eus = eu_count;
+            device_info.num_subslices = subslice_count;
+            info!(
+                "redox-drm-intel: detected {} EUs across {} subslices",
+                eu_count, subslice_count
+            );
+        }
+
         let lmem = if let Some(lmem_bar) = lmem_bar_info {
             if lmem_bar.size > 0 && lmem_bar.is_memory() {
                 let lmem_mmio = map_bar(&mut device, &lmem_bar, "Intel LMEM BAR")?;