From 4822991becc3afe9621cf3490291ee178bae2e6d Mon Sep 17 00:00:00 2001
From: Duncan Tourolle <duncan@tourolle.paris>
Date: Sun, 4 Oct 2026 22:26:56 -0400
Subject: [PATCH] Read an unknown SoC as Qualcomm's
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The generic runtime is opened only when the QNN build does not fit, and
the fit rests on ro.soc.manufacturer. A property the app cannot read, or
an Android older than 12 that has none, read as "not Qualcomm" would
put a Qualcomm device on the generic rung and off its Hexagon — what
0.22.1 had just fixed. Only a device that names another vendor is now
not Qualcomm's; the tablet reports QTI.
---
 core/dr-inference-engine/src/hardware.rs | 33 +++++++++++++++++++-----
 1 file changed, 26 insertions(+), 7 deletions(-)

diff --git a/core/dr-inference-engine/src/hardware.rs b/core/dr-inference-engine/src/hardware.rs
index c26369c..fe58e18 100644
--- a/core/dr-inference-engine/src/hardware.rs
+++ b/core/dr-inference-engine/src/hardware.rs
@@ -95,10 +95,12 @@ pub fn detect() -> Gpus {
 
 #[cfg(target_os = "android")]
 pub fn detect() -> Gpus {
-    // `ro.soc.manufacturer` exists from Android 12. Qualcomm's FastRPC
-    // library, which the Hexagon path loads anyway, is the second witness:
-    // a Qualcomm device read as anything else would trade its NPU for the
-    // generic rung.
+    // Fail-safe: only a device that names another vendor is not Qualcomm.
+    // `ro.soc.manufacturer` exists from Android 12, and a property or file
+    // the app cannot read reads as nothing; nothing keeps the QNN build
+    // first, as 0.22 had it, where a Qualcomm device mistaken for another
+    // would trade its NPU for the generic rung. Qualcomm's FastRPC library,
+    // which the Hexagon path loads anyway, overrules a name.
     let soc = crate::probe::system_property("ro.soc.manufacturer");
     let fastrpc = [
         "/vendor/lib64/libcdsprpc.so",
@@ -107,13 +109,19 @@ pub fn detect() -> Gpus {
     .iter()
     .any(|p| std::path::Path::new(p).exists());
     Gpus {
-        qualcomm: soc.eq_ignore_ascii_case("QTI")
-            || soc.eq_ignore_ascii_case("Qualcomm")
-            || fastrpc,
+        qualcomm: qualcomm_soc(&soc) || fastrpc,
         ..Gpus::default()
     }
 }
 
+/// Whether `ro.soc.manufacturer` leaves the device Qualcomm's: it says so,
+/// or it says nothing.
+#[cfg(any(target_os = "android", test))]
+fn qualcomm_soc(manufacturer: &str) -> bool {
+    let m = manufacturer.trim();
+    m.is_empty() || m.eq_ignore_ascii_case("QTI") || m.eq_ignore_ascii_case("Qualcomm")
+}
+
 #[cfg(not(any(target_os = "linux", target_os = "windows", target_os = "android")))]
 pub fn detect() -> Gpus {
     Gpus::default()
@@ -127,6 +135,17 @@ mod tests {
         p.iter().map(|s| s.to_string()).collect()
     }
 
+    #[test]
+    fn only_a_named_other_vendor_is_not_qualcomm() {
+        assert!(qualcomm_soc("QTI"));
+        assert!(qualcomm_soc("Qualcomm"));
+        // Unreadable, or older than Android 12: the QNN build stays first.
+        assert!(qualcomm_soc(""));
+        assert!(!qualcomm_soc("Mediatek"));
+        assert!(!qualcomm_soc("Google"));
+        assert!(!qualcomm_soc("Samsung"));
+    }
+
     #[test]
     fn the_card_beats_the_integrated_gpu_and_both_beat_the_generic_rung() {
         let cpu = offers(&["CPUExecutionProvider"]);