[linux-next:master 1843/2633] drivers/net/ethernet/airoha/airoha_ppe.c:122 airoha_ppe_set_xmit_frame_size() warn: subtract is higher precedence than shift

[linux-next:master 1843/2633] drivers/net/ethernet/airoha/airoha_ppe.c:122 airoha_ppe_set_xmit_frame_size() warn: subtract is higher precedence than shift

[kernel test robot]

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
TO: Lorenzo Bianconi <lorenzo@kernel.org>
CC: Paolo Abeni <pabeni@redhat.com>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   4f441960e691d37c880d2cc004de06bb5b6bd5e4
commit: a7c6debfec17381329b094bd75560a1e57a5533a [1843/2633] net: airoha: fix max receive size configuration
:::::: branch date: 13 hours ago
:::::: commit date: 2 days ago
config: sh-randconfig-r072-20260702 (https://download.01.org/0day-ci/archive/20260702/202607021219.DdV9vXcX-lkp@intel.com/config)
compiler: sh4-linux-gcc (GCC) 15.2.0
smatch: v0.5.0-9185-gbcc58b9c

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <error27@gmail.com>
| Closes: https://lore.kernel.org/r/202607021219.DdV9vXcX-lkp@intel.com/

New smatch warnings:
drivers/net/ethernet/airoha/airoha_ppe.c:122 airoha_ppe_set_xmit_frame_size() warn: subtract is higher precedence than shift
drivers/net/ethernet/airoha/airoha_ppe.c:122 airoha_ppe_set_xmit_frame_size() warn: subtract is higher precedence than shift
drivers/net/ethernet/airoha/airoha_ppe.c:122 airoha_ppe_set_xmit_frame_size() warn: subtract is higher precedence than shift
drivers/net/ethernet/airoha/airoha_ppe.c:122 airoha_ppe_set_xmit_frame_size() warn: subtract is higher precedence than shift

Old smatch warnings:
drivers/net/ethernet/airoha/airoha_ppe.c:95 airoha_ppe_set_cpu_port() warn: subtract is higher precedence than shift
drivers/net/ethernet/airoha/airoha_ppe.c:95 airoha_ppe_set_cpu_port() warn: subtract is higher precedence than shift
drivers/net/ethernet/airoha/airoha_ppe.c:95 airoha_ppe_set_cpu_port() warn: subtract is higher precedence than shift
drivers/net/ethernet/airoha/airoha_ppe.c:95 airoha_ppe_set_cpu_port() warn: subtract is higher precedence than shift

vim +122 drivers/net/ethernet/airoha/airoha_ppe.c

f44218cd5e6a3d Lorenzo Bianconi 2026-03-17   99  
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  100  void airoha_ppe_set_xmit_frame_size(struct airoha_gdm_dev *dev)
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  101  {
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  102  	struct airoha_gdm_port *port = dev->port;
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  103  	struct airoha_eth *eth = dev->eth;
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  104  	int i, ppe_id, index;
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  105  	u32 len = 0;
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  106  
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  107  	for (i = 0; i < ARRAY_SIZE(port->devs); i++) {
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  108  		struct airoha_gdm_dev *d = port->devs[i];
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  109  		struct net_device *netdev;
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  110  
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  111  		if (!d)
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  112  			continue;
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  113  
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  114  		netdev = netdev_from_priv(d);
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  115  		if (netif_running(netdev))
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  116  			len = max_t(u32, len, netdev->mtu);
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  117  	}
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  118  	len += VLAN_ETH_HLEN;
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  119  
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  120  	ppe_id = !airoha_is_lan_gdm_dev(dev) && airoha_ppe_is_enabled(eth, 1);
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  121  	index = port->id == AIROHA_GDM4_IDX ? 7 : port->id;
a7c6debfec1738 Lorenzo Bianconi 2026-06-25 @122  	airoha_fe_rmw(eth, REG_PPE_MTU(ppe_id, index),
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  123  		      FP_EGRESS_MTU_MASK(index),
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  124  		      __field_prep(FP_EGRESS_MTU_MASK(index), len));
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  125  }
a7c6debfec1738 Lorenzo Bianconi 2026-06-25  126  

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