linux-kernel - Re: [PATCH 6/9] clk: davinci: pll: allow dev == NULL

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Date:   Wed, 30 May 2018 14:59:01 -0500
From:   David Lechner <david@...hnology.com>
To:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>
Cc:     linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Sekhar Nori <nsekhar@...com>,
        Kevin Hilman <khilman@...nel.org>,
        linux-kernel@...r.kernel.org, brgl@...ev.pl
Subject: Re: [PATCH 6/9] clk: davinci: pll: allow dev == NULL

On 05/30/2018 02:46 PM, Michael Turquette wrote:
> Hi David,
> 
> Quoting David Lechner (2018-05-25 11:11:47)
>> This modifies the TI Davinci PLL clock driver to allow for the case
>> when dev == NULL. On some (most) SoCs that use this driver, the PLL
>> clock needs to be registered during early boot because it is used
>> for clocksource/clkevent and there will be no platform device available.
> 
> A lot of this stuff feels like a step backwards. E.g:
> 
>> diff --git a/drivers/clk/davinci/pll.c b/drivers/clk/davinci/pll.c
>> index 23a24c944f1d..2eb981e61185 100644
>> --- a/drivers/clk/davinci/pll.c
>> +++ b/drivers/clk/davinci/pll.c
>> @@ -11,6 +11,7 @@
>>   
>>   #include <linux/clk-provider.h>
>>   #include <linux/clk.h>
>> +#include <linux/clk/davinci.h>
>>   #include <linux/delay.h>
>>   #include <linux/err.h>
>>   #include <linux/io.h>
>> @@ -223,6 +224,7 @@ static const struct clk_ops dm365_pll_ops = {
>>   
>>   /**
>>    * davinci_pll_div_register - common *DIV clock implementation
>> + * @dev: The PLL platform device or NULL
>>    * @name: the clock name
>>    * @parent_name: the parent clock name
>>    * @reg: the *DIV register
>> @@ -240,17 +242,21 @@ static struct clk *davinci_pll_div_register(struct device *dev,
>>          const struct clk_ops *divider_ops = &clk_divider_ops;
>>          struct clk_gate *gate;
>>          struct clk_divider *divider;
>> +       struct clk *clk;
>> +       int ret;
>>   
>> -       gate = devm_kzalloc(dev, sizeof(*gate), GFP_KERNEL);
>> +       gate = kzalloc(sizeof(*gate), GFP_KERNEL);
>>          if (!gate)
>>                  return ERR_PTR(-ENOMEM);
>>   
>>          gate->reg = reg;
>>          gate->bit_idx = DIV_ENABLE_SHIFT;
>>   
>> -       divider = devm_kzalloc(dev, sizeof(*divider), GFP_KERNEL);
>> -       if (!divider)
>> -               return ERR_PTR(-ENOMEM);
>> +       divider = kzalloc(sizeof(*divider), GFP_KERNEL);
>> +       if (!divider) {
>> +               ret = -ENOMEM;
>> +               goto err_free_gate;
>> +       }
>>   
>>          divider->reg = reg;
>>          divider->shift = DIV_RATIO_SHIFT;
> 
> Oh no my poor devm_ helpers!
> 
> I understand that we need to support early boot drivers better, so this
> patch can be merged.
> 
> However I'm curious if you're tracking Bartosz's early_platform_driver
> efforts? Converting to that if it is ever merged would likely be
> cleaner:
> 
> https://lkml.kernel.org/r/20180511162028.20616-1-brgl@bgdev.pl
> 
> Best regards,
> Mike
> 

Yes. In fact, this is what got Bartosz working on it in the first
place. :-)