Re: Change ABI of mii_readreg() and mii_writereg()

[Masanobu SAITOH <msaitoh%execsw.org@localhost>]

On 2018/12/25 17:04, Masanobu SAITOH wrote:
>   Hi.
>
>   Our mii(4)'s mii_readreg() and mii_writereg() are defined as below:
>
> > /*
> >  * Callbacks from MII layer into network interface device driver.
> >  */
> > typedef int (*mii_readreg_t)(device_t, int, int);
> > typedef void (*mii_writereg_t)(device_t, int, int, int);
>
>   There is no formal way to tell any error (e.g. protocol error or timeout).
> By this flaw, we had some bugs and fixed them many times.
>
>   On some driver, if the return value of mii_readreg() is all 0 or all 1,
> it regards as error. It's not good because some MII PHY registers are
> counter.
>
>   In 802.3 spec also says that the PHY shall not respond to read/write
> transaction to the unimplemented register(22.2.4.3), so the device timeout
> is exist in real. It can be used to detect whether a register is implemented
> or not (if the register conforms to the spec).

s/the register/the PHY/


>   Some Ethernet controller or system are required to take a semaphore
> while accessing the PHY. It might be failed to get the semaphore.
>
> So, I propose to change the API as follows
> (I also change read/write register value from int to uint16_t because
> all of the register is 16bit (and it should be unsigned)):
>
> int (*mii_readreg_t)(device_t, int, int, uint16_t *);
> int (*mii_writereg_t)(device_t, int, int, uint16_t);
>
>   OK?


--
-----------------------------------------------
                SAITOH Masanobu (msaitoh%execsw.org@localhost
                                 msaitoh%netbsd.org@localhost)