net: dsa/mv88e6xxx: add reg read and write debug

This commit adds debug messages for the generic mv88e6xxx read and write
routines. The output is similar to this:

    mdio-gpio mdio-gpio.0: <- addr: 0x1b reg: 0x05 val: 0x4000
    mdio-gpio mdio-gpio.0: -> addr: 0x1b reg: 0x07 val: 0x3113
    mdio-gpio mdio-gpio.0: -> addr: 0x1b reg: 0x08 val: 0x0330
    mdio-gpio mdio-gpio.0: -> addr: 0x1b reg: 0x09 val: 0x0000

This is convenient to dynamically debug operations through debugfs with:

    echo file mv88e6xxx.c +p > <debugfs>/dynamic_debug/control

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/dsa/mv88e6xxx.c b/drivers/net/dsa/mv88e6xxx.c
index cd6807c6b4eddaec7eb57ebc2107c0290ff1018f..3e7e31a6abb73f28ea44c9314c4f3628337edab7 100644 (file)
--- a/drivers/net/dsa/mv88e6xxx.c
+++ b/drivers/net/dsa/mv88e6xxx.c
@@ -85,6 +85,12 @@ int mv88e6xxx_reg_read(struct dsa_switch *ds, int addr, int reg)
        ret = __mv88e6xxx_reg_read(bus, ds->pd->sw_addr, addr, reg);
        mutex_unlock(&ps->smi_mutex);
 
+       if (ret < 0)
+               return ret;
+
+       dev_dbg(ds->master_dev, "<- addr: 0x%.2x reg: 0x%.2x val: 0x%.4x\n",
+               addr, reg, ret);
+
        return ret;
 }
 
@@ -128,6 +134,9 @@ int mv88e6xxx_reg_write(struct dsa_switch *ds, int addr, int reg, u16 val)
        if (bus == NULL)
                return -EINVAL;
 
+       dev_dbg(ds->master_dev, "-> addr: 0x%.2x reg: 0x%.2x val: 0x%.4x\n",
+               addr, reg, val);
+
        mutex_lock(&ps->smi_mutex);
        ret = __mv88e6xxx_reg_write(bus, ds->pd->sw_addr, addr, reg, val);
        mutex_unlock(&ps->smi_mutex);