Re: [PATCH 3/5] net: add Hisilicon Network Subsystem MDIO support

Arnd Bergmann
2015-08-14T20:57:28Z

On Friday 14 August 2015 18:30:20 Kenneth Lee wrote:

> +#define MDIO_BASE_ADDR 0x403C0000

Does not belong in here (and is not used)

> +#define MDIO_COMMAND_REG 0x0
> +#define MDIO_ADDR_REG 0x4
> +#define MDIO_WDATA_REG 0x8
> +#define MDIO_RDATA_REG 0xc
> +#define MDIO_STA_REG 0x10

These look suspiciously similar to definitions from
drivers/net/ethernet/hisilicon/hip04_mdio.c.

Could the hardware be related? If so, please try to share
the common parts.

> +static inline void mdio_write_reg(void *base, u32 reg, u32 value)
> +{
> + u8 __iomem *reg_addr = ACCESS_ONCE(base);
> +
> + writel(value, reg_addr + reg);
> +}
> +
> +#define MDIO_WRITE_REG(a, reg, value) \
> + mdio_write_reg((a)->vbase, (reg), (value))
>

Something seems wrong here: why do you have an ACCESS_ONCE() on a
local variable? Doesn't this just make the code less efficient
without providing lockless access to shared variables?

The types are inconsistent here, you should get a warning from
running this through 'make C=1' because of the missing __iomem
annotation of the pointer.

Also, why both a macro and an inline function? Just use an inline
function.

Arnd