lkml.org 
[lkml]   [2015]   [Jan]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH 2/2] cpufreq: add cpufreq driver for Mediatek MT8173 SoC
From
On 20 January 2015 at 00:00, Mike Turquette <mturquette@linaro.org> wrote:
> Quoting pi-cheng.chen (2015-01-09 01:54:51)
>> diff --git a/drivers/cpufreq/mt8173-cpufreq.c b/drivers/cpufreq/mt8173-cpufreq.c
>> new file mode 100644
>> index 0000000..b578c10
>> --- /dev/null
>> +++ b/drivers/cpufreq/mt8173-cpufreq.c
>> @@ -0,0 +1,459 @@

Hello Mike,

>
> Hello Pi-Cheng,
>
> <snip>
>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/of_address.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/cpufreq.h>
>> +#include <linux/cpufreq-dt.h>
>> +#include <linux/cpumask.h>
>> +#include <linux/slab.h>
>> +#include <linux/clk.h>
>> +#include <linux/clk-provider.h>
>
> I'll echo what Viresh said here. CPUfreq drivers should typically be
> clock consumers and only require clk.h, not clk-provider.h. More on that
> below.
>

I included it because of the __clk_lookup call. But yes, I will use the clk_get
to get the intermediate clock to get rid of this.

> <snip>
>
>> +static void cpuclk_mux_set(int cluster, u32 sel)
>> +{
>> + u32 val;
>> + u32 mask = 0x3;
>> +
>> + if (cluster == BIG_CLUSTER) {
>> + mask <<= 2;
>> + sel <<= 2;
>> + }
>> +
>> + spin_lock(&lock);
>> +
>> + val = readl(clk_mux_regs);
>> + val = (val & ~mask) | sel;
>> + writel(val, clk_mux_regs);
>> +
>> + spin_unlock(&lock);
>> +}
>
> Is cpuclk a mux that is represented in the MT8173 clock driver? It looks
> like a clock that belong to the clock driver, but this cpufreq driver is
> writing to that register directly.
>

Yes, it's a mux but not presented in MT8173 clock driver yet. Therefore I
map the HW register and writing them directly to do reparent. I will get
rid of it once I got those muxes presented in MT8173 clock driver.

> <snip>
>
>> +static int mt8173_cpufreq_dvfs_info_init(void)
>> +{
>
> <snip>
>
>> + mainpll = __clk_lookup("mainpll");
>> + if (!mainpll) {
>> + pr_err("failed to get mainpll clk\n");
>> + ret = -ENOENT;
>> + goto dvfs_info_release;
>> + }
>> + mainpll_freq = clk_get_rate(mainpll);
>
> This is definitely bad. Why not use clk_get() here? __clk_lookup should
> not be exposed to clock consumer drivers (and I hope to get rid of it
> completely some day).
>

Thanks for pointing me out the right API to do it. I will fix it in
next version.

Best Regards,
Pi-Cheng

> Regards,
> Mike


\
 
 \ /
  Last update: 2015-01-20 08:41    [W:0.091 / U:0.152 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site