Re: [PATCH] i2c: pxa: enable high speed mode for i2c bus

[James Lebron <leileishangchina-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Hi All

Would you please help to look at this patch?

Thanks!

2013/7/22 James Lebron <leileishangchina-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
> Hi Guys
>
>       Any comments?
>
> 2013/7/11 James Lebron <leileishangchina-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
>> Hi all
>>
>>       I am still waiting for your response.....
>>
>> 2013/7/5 James Lebron <leileishangchina-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
>>> Hi guys,
>>>
>>>         Any comments?
>>>
>>> 2013/7/2 James Lebron <leileishangchina-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
>>>> Hi Wolfram
>>>>
>>>>     Have you finished reading datasheet?
>>>>
>>>> 2013/6/15 Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>:
>>>>> Hi,
>>>>>
>>>>> On Fri, Jun 07, 2013 at 02:38:17PM +0800, Leilei Shang wrote:
>>>>>> To enter high speed mode, following steps should be done:
>>>>>> 1. When running in high speed mode, i2c clock rate is different
>>>>>> from standard mode. Clock rate must be set according to
>>>>>> specification first.
>>>>>> 2. When i2c controller sends a master code and wins arbitration,
>>>>>> high speed mode is entered.
>>>>>>
>>>>>> If you want to enable high speed mode, the following members of
>>>>>> platform data should be set to proper value:
>>>>>
>>>>> I couldn't find any support for hs-mode in pxa2xx and pxa3xx. So it
>>>>> shouldn't be set in platform data, but depending on checks if this is
>>>>> supported on this device at all. And why don't simply switch to it if
>>>>> rate is bigger than what is supported without hs-mode?
>>>>>
>>>>
>>>> 1. High speed mode is hardware feature, you can't read it from
>>>> software. It's similar to fast mode, and fast mode is set in platform
>>>> data.
>>>>
>>>>     The only method I can think of is to add a platform, like pxa910.
>>>> And if you enable hs mode and platform is not pxa910, we'll set it to
>>>> normal mode. Is this OK?
>>>>
>>>> 2. About hs mode clock setting. We don't know whether currently hs
>>>> mode clock will be changed in future. Do you think below code is OK?
>>>>
>>>> if (i2c->rate)
>>>>             clk_set_rate(i2c->clk, i2c->rate);
>>>> else
>>>>             clk_set_rate(i2c->clk, 62400000);
>>>>
>>>>             pr_info("i2c: <%s> set rate to %ld\n",
>>>>                 i2c->adap.name, clk_get_rate(i2c->clk));
>>>>
>>>>>> 1. "high_mode" should be set to "1".
>>>>>> 2. "master_code" should be set to "8'b 0000_1xxx"(x is 0 or 1).
>>>>>>    If no master_code is set, set to default value 0xe.
>>>>>> 3. "rate" should be set according to specification.
>>>>>
>>>>> Note that you should fall back to full-speed mode after sending the stop
>>>>> bit in high-speed mode. I can't find this in the code?
>>>>>
>>>>
>>>> 3. Will fall back to normal mode when stop bit is sent.
>>>>
>>>>>>
>>>>>> Signed-off-by: Leilei Shang <shangll-eYqpPyKDWXRBDgjK7y7TUQ@public.gmane.org>
>>>>>
>>>>> Which SoC supports this? I'd like to have a look at the datasheet.
>>>>>
>>>>> Thanks,
>>>>>
>>>>>    Wolfram
>>>>>
>>>>
>>>> Hope you can reply soon!
>>>>
>>>> Best regards
>>>> Leilei