airoha: npu: load the firmware without the sysfs fallback

The NPU driver maps a missing firmware file to -EPROBE_DEFER, so that it
can be retried once the rootfs carrying /lib/firmware is mounted. That
mapping holds only while request_firmware() reports -ENOENT, and it does
not when the sysfs fallback is in play: the request goes to a userspace
helper, blocks for the full 60 second loading_timeout and comes back as
-ETIMEDOUT, which dev_err_probe() then turns into a hard failure. The
board boots a minute slower and ends up with no NPU at all, so no
hardware flow offloading either.

Our own config disables FW_LOADER_USER_HELPER for the target, but that
is not a dependable guard: LEDS_LP55XX_COMMON selects it, so any build
that pulls in kmod-leds-lp55xx-common - every image built with
ALL_KMODS, snapshots included - gets it back, and generic's
FW_LOADER_USER_HELPER_FALLBACK=y then arms the fallback.

Add a patch switching the driver to request_firmware_direct(), which
sets FW_OPT_NOFALLBACK_SYSFS and so reports -ENOENT whatever the
firmware loader is configured to do.

request_firmware_direct() also sets FW_OPT_NO_WARN, so the "Direct
firmware load for airoha/en7581_npu_rv32.bin failed with error -2"
line goes away together with the fallback. There is no variant that
skips the fallback but keeps the warning. While the probe is being
deferred that message was noise, but on a board where the firmware
package is genuinely missing it was the only hint naming the file.

Measured on a Nokia XG-040G-MD with FW_LOADER_USER_HELPER=y and
FW_LOADER_USER_HELPER_FALLBACK=y forced on, the two images differing
only by this patch:

  without:  2.477 fallback -> 64.555 -ETIMEDOUT -> probe failed -110,
            preinit at 69.6s, NPU unbound
  with:     no fallback and no warning at all, NPU fw version 1456.62
            at 3.665s, preinit at 7.6s

Note the fallback is still compiled in and forced in both cases; the
patch does not disable it, it only keeps the driver from falling into
it.

The patch carries Fixes: 23290c7bc190 ("net: airoha: Introduce Airoha
NPU support") and Cc: stable@vger.kernel.org, so it can be dropped once
it lands upstream and reaches us through a stable update.

Link: https://lore.kernel.org/netdev/20260807024125.434055-1-sochnev.v.74@gmail.com/
Signed-off-by: Vitaliy Sochnev <sochnev.v.74@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/24593
Signed-off-by: Robert Marko <robimarko@gmail.com>

target/linux/airoha/patches-6.18/921-net-airoha-npu-load-firmware-without-the-sysfs-fallb.patch

@@ -0,0 +1,59 @@
+From 0509cfb2607a5a084617701f969b4bad0fd0f157 Mon Sep 17 00:00:00 2001
+From: Vitaliy Sochnev <sochnev.v.74@gmail.com>
+Date: Fri, 7 Aug 2026 03:37:00 +0100
+Subject: [PATCH] net: airoha: npu: load the firmware without the sysfs
+ fallback
+
+airoha_npu_load_firmware() maps a missing firmware file to -EPROBE_DEFER
+so that the NPU can be brought up once the rootfs carrying /lib/firmware
+has been mounted. That mapping holds only as long as request_firmware()
+reports -ENOENT.
+
+It does not when the sysfs fallback is in play. With
+CONFIG_FW_LOADER_USER_HELPER_FALLBACK set, or with the fallback armed at
+runtime through /proc/sys/kernel/firmware_config/force_sysfs_fallback,
+request_firmware() hands the request to a userspace helper, waits out the
+full loading_timeout and returns -ETIMEDOUT. The -ENOENT test no longer
+matches, dev_err_probe() turns the result into a hard failure, and the
+NPU is left unbound after stalling the boot for 60 seconds:
+
+  airoha-npu 1e900000.npu: Direct firmware load for airoha/en7581_npu_rv32.bin failed with error -2
+  airoha-npu 1e900000.npu: Falling back to sysfs fallback for: airoha/en7581_npu_rv32.bin
+  airoha-npu 1e900000.npu: error -ETIMEDOUT: failed to run npu firmware
+  airoha-npu 1e900000.npu: probe with driver airoha-npu failed with error -110
+
+Clearing FW_LOADER_USER_HELPER in the configuration is not a dependable
+guard against this, because unrelated drivers select it. On the affected
+build the symbol was turned back on by LEDS_LP55XX_COMMON, even though
+the platform had explicitly disabled it.
+
+request_firmware_direct() sets FW_OPT_NOFALLBACK_SYSFS, so a missing file
+is reported as -ENOENT whatever the firmware loader is configured to do,
+and the deferred probe path works as it was meant to.
+
+Measured on a Nokia XG-040G-MD with FW_LOADER_USER_HELPER=y and
+FW_LOADER_USER_HELPER_FALLBACK=y, on two images from the same tree
+differing only by this patch: without it the probe fails with
+-ETIMEDOUT after 64.5s and the NPU stays unbound, with it the NPU
+reports its firmware version at 3.7s. The fallback is compiled in and
+forced in both cases; the patch does not disable it, it only keeps the
+driver from falling into it.
+
+Fixes: 23290c7bc190 ("net: airoha: Introduce Airoha NPU support")
+Cc: stable@vger.kernel.org
+Signed-off-by: Vitaliy Sochnev <sochnev.v.74@gmail.com>
+---
+ drivers/net/ethernet/airoha/airoha_npu.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/drivers/net/ethernet/airoha/airoha_npu.c
++++ b/drivers/net/ethernet/airoha/airoha_npu.c
+@@ -202,7 +202,7 @@ static int airoha_npu_load_firmware(stru
+ 	const struct firmware *fw;
+ 	int ret;
+ 
+-	ret = request_firmware(&fw, fw_name, dev);
++	ret = request_firmware_direct(&fw, fw_name, dev);
+ 	if (ret)
+ 		return ret == -ENOENT ? -EPROBE_DEFER : ret;
+