Hi Wolfram
Have you finished reading datasheet?
2013/6/15 Wolfram Sang <wsa@xxxxxxxxxxxxx>:
> 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@xxxxxxxxxxx>
>
> Which SoC supports this? I'd like to have a look at the datasheet.
>
> Thanks,
>
> Wolfram
>
Hope you can reply soon!
Best regards
Leilei
--
To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
