Re: [PATCH 6/6 v6] cpufreq, highbank: add support for highbank cpufreq

Mark Langsdorf
2012-11-28T13:16:12Z

On 11/27/2012 08:32 PM, Shawn Guo wrote:
> On Tue, Nov 27, 2012 at 02:04:32PM -0600, Mark Langsdorf wrote:
>> Highbank processors depend on the external ECME to perform voltage
>> management based on a requested frequency. Communication between the
>> A9 cores and the ECME happens over the pl320 IPC channel.
>
> ...
>
>> +static int hb_voltage_change(unsigned int freq)
>> +{
>> + int i;
>> + u32 msg[7];
>> +
>> + msg[0] = HB_CPUFREQ_CHANGE_NOTE;
>> + msg[1] = freq / 1000;
>> + for (i = 2; i < 7; i++)
>> + msg[i] = 0;
>> +
>> + return pl320_ipc_transmit(msg);
>
> Is it possible to have this handled inside clk_set_rate() call of cpu
> clock?

Standard practice is to have cpufreq_set_target() handle voltage
transitions and leave clk_set_rate() handle the frequency changes. I'd
have to move most of the logic of hb_set_target() into
clk_highbank.c:clk_pll_set_rate() and then add extra logic for when
cpufreq is not enabled/loaded. I don't think the clk maintainers would
take that patch, either.

So no.

--Mark Langsdorf
Calxeda, Inc.