Fix compilation on Linux kernel 6.16+

[philiplinden]

Add ccflags-y declarations alongside EXTRA_CFLAGS for modern kernel build system compatibility. Resolves incompatible pointer type error in ethtool get_ts_info callback.

AX88279 Driver Compilation Fix for Linux Kernel 6.16+

Problem Summary

The ASIX AX88279 USB Ethernet driver (v3.5.16) with PTP support fails to compile on Arch Linux 6.16.8-arch3-1. Two compatibility issues were identified:

1. Deprecated Makefile syntax: The driver uses EXTRA_CFLAGS which is deprecated in newer kernel build systems
2. Kernel API change: The ethtool get_ts_info callback signature changed in recent kernels

Error Messages

ax88179a_772d.c:539:27: error: initialization of 'int (*)(struct net_device *, struct kernel_ethtool_ts_info *)' from incompatible pointer type 'int (*)(struct net_device *, struct ethtool_ts_info *)' [-Wincompatible-pointer-types]

Required Changes

1. Makefile (Add ccflags-y alongside EXTRA_CFLAGS)

Update the Makefile to use both EXTRA_CFLAGS (for older kernels) and ccflags-y (for newer kernels). Add ccflags-y declarations for all conditional compilation flags:

Line 19-20: Add ccflags-y initialization

EXTRA_CFLAGS = -fno-pie
ccflags-y = -fno-pie

For each ENABLE_* flag, add ccflags-y alongside EXTRA_CFLAGS

Example pattern:

ifeq ($(ENABLE_PTP_FUNC), y)
	$(TARGET)-objs += ax_ptp.o
	EXTRA_CFLAGS += -DENABLE_PTP_FUNC
	ccflags-y += -DENABLE_PTP_FUNC    # ADD THIS LINE
ifeq ($(ENABLE_PTP_DEBUG), y)
	EXTRA_CFLAGS += -DENABLE_PTP_DEBUG
	ccflags-y += -DENABLE_PTP_DEBUG    # ADD THIS LINE
endif
endif

Apply this pattern to all flags:

• ENABLE_IOCTL_DEBUG
• ENABLE_AUTODETACH_FUNC
• ENABLE_MAC_PASS
• ENABLE_INT_AGGRESSIVE
• ENABLE_INT_POLLING
• ENABLE_AUTOSUSPEND
• ENABLE_TX_TASKLET
• ENABLE_RX_TASKLET
• ENABLE_PTP_FUNC
• ENABLE_PTP_DEBUG
• ENABLE_QUEUE_PRIORITY
• ENABLE_AX88279

2. ax88179a_772d.c (Fix ethtool API signature)

Change the function signature at line 468-469:

BEFORE:

#ifdef ENABLE_PTP_FUNC
static int ax88179a_set_wol_get_ts_info
(struct net_device *dev, struct ethtool_ts_info *info)

AFTER:

#ifdef ENABLE_PTP_FUNC
static int ax88179a_set_wol_get_ts_info
(struct net_device *dev, struct kernel_ethtool_ts_info *info)

Verification

After changes, compilation should succeed:

make clean && make

Expected output should show successful compilation of ax_usb_nic.ko without errors.

Impact

• No functional changes to driver behavior
• Pure API compatibility fix for kernel 6.16+
• Both changes are required for successful compilation
• The function body remains unchanged; only the type signature updates to match the kernel API

[philiplinden]

@ahmadexp anything else to do here before it can be merged?