Re: [PATCH 12/37] clk: renesas: rzg2l: reduce the critical area

[claudiu beznea]

On 14.09.2023 16:12, Geert Uytterhoeven wrote:
> Hi Claudiu,
> 
> On Tue, Sep 12, 2023 at 6:52 AM Claudiu <claudiu.beznea@xxxxxxxxx> wrote:
>> From: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
>>
>> spinlock in rzg2l_mod_clock_endisable() is intended to protect the accesses
>> to hardware register. There is no need to protect the instructions that set
>> temporary variable which will be then written to register. Thus limit the
>> spinlock only to the hardware register access.
>>
>> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
> 
> Thanks for your patch!
> 
>> --- a/drivers/clk/renesas/rzg2l-cpg.c
>> +++ b/drivers/clk/renesas/rzg2l-cpg.c
>> @@ -912,13 +912,13 @@ static int rzg2l_mod_clock_endisable(struct clk_hw *hw, bool enable)
>>
>>         dev_dbg(dev, "CLK_ON %u/%pC %s\n", CLK_ON_R(reg), hw->clk,
>>                 enable ? "ON" : "OFF");
>> -       spin_lock_irqsave(&priv->rmw_lock, flags);
>>
>>         value = bitmask << 16;
>>         if (enable)
>>                 value |= bitmask;
>> -       writel(value, priv->base + CLK_ON_R(reg));
>>
>> +       spin_lock_irqsave(&priv->rmw_lock, flags);
>> +       writel(value, priv->base + CLK_ON_R(reg));
>>         spin_unlock_irqrestore(&priv->rmw_lock, flags);
> 
> After this, it becomes obvious there is nothing to protect at all,
> so the locking can just be removed from this function?

I tend to be paranoid when writing to hardware resources thus I kept it.
Would you prefer to remove it at all?

> 
> Gr{oetje,eeting}s,
> 
>                         Geert
>