about iicdev_writeto() on ralink soc

[Mori Hiroki]

Hi

FYI

This is RT2880 i2c signal by my driver code.

https://flic.kr/p/ZC3HQZ


----- Original Message -----
> From: Mori Hiroki <yamori813 at yahoo.co.jp>
> To: Ian Lepore <ian at freebsd.org>
> Cc: "freebsd-mips at freebsd.org" <freebsd-mips at freebsd.org>
> Date: 2017/10/21, Sat 08:04
> Subject: Re: about iicdev_writeto() on ralink soc
> 
> Hi
> 
> 
> ----- Original Message -----
>>  From: Ian Lepore <ian at freebsd.org>
>>  To: Mori Hiroki <yamori813 at yahoo.co.jp>
>>  Cc: "freebsd-mips at freebsd.org" <freebsd-mips at freebsd.org>
>>  Date: 2017/10/21, Sat 00:00
>>  Subject: Re: about iicdev_writeto() on ralink soc
>> 
>>  On Fri, 2017-10-20 at 20:24 +0900, Mori Hiroki wrote:
>>>   Hi
>>> 
>>>   I make mips mediatek iic driver. Mediatek(Ralink) soc(RT2880 and 
>>>   RT3050) is not support nostop option at I2C device. This soc i2c
>>>   device is set transfer length and automatically send stop. And
>>>   Always send device address at first byte.
>>> 
>>>   your added iicdev_writeto() not work in these soc i2c device.
>>> 
>>> 
>>> 
>>>   https://svnweb.freebsd.org/base?view=revision&revision=321583
>>> 
>>> 
>>>   Could you please change single transfer in iicdev_writeto() at
>>>   iiconf.c.
>>> 
>>>   Regards
>>> 
>>>   Hiroki Mori
>>  
> 
> Thanks check RT datasheet.
> 
>>  iicdev_writeto() does the correct sequence of operations.
>> 
>>  I think if you set the ADDRDIS bit in the device control register and
>>  ignore the NOSTOP flag in the messages, it will work for most slave
>>  devices.  Some slave devices require a repeat-start to work correctly,
>>  and those will never work right on a controller like this.
>> 
>>  -- Ian
>> 
> 
> No.
> 
> Ralink Datasheet is very confuse. ADDRDIR is register address disable.
> DEVADDIS is device address disable. 
> 
> If not set DEVADDIS and ADDRDIR then
> 
> <Device address> <Register address> <data> ...
> 
> If set ADDRDIR then 
> 
> <Device address> <data> ...
> 
> If set DEVADDIS then ignore ADDRDIR
> 
> <Register address> <data> ...
> 
> always two more byte send this soc.
> 
> Driver review is this.
> 
> https://reviews.freebsd.org/D12736
> 
> 
> Thanks
> 
> Hiroki Mori
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