linux-kernel - Re: [PATCH] pinctrl: stm32: improve bank clocks management

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Date:   Tue, 26 Apr 2022 00:07:13 +0200
From:   Marek Vasut <marex@...x.de>
To:     Fabien DESSENNE <fabien.dessenne@...s.st.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        linux-gpio@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] pinctrl: stm32: improve bank clocks management

On 4/25/22 11:27, Fabien DESSENNE wrote:
> Hi Marek
> 
> 
> On 22/04/2022 18:26, Marek Vasut wrote:
>> On 4/22/22 16:36, Fabien Dessenne wrote:
>>> Instead of enabling/disabling the clock at each IO configuration update,
>>> just keep the clock enabled from the probe.
>>> This makes things simpler and more efficient (e.g. the time required to
>>> toggle an output IO is drastically decreased) without significantly
>>> increasing the power consumption.
>>
>> [...]
>>
>>>   static struct irq_domain *stm32_pctrl_get_irq_domain(struct 
>>> device_node *np)
>>> @@ -1575,6 +1537,10 @@ int stm32_pctl_probe(struct platform_device 
>>> *pdev)
>>>               ret = stm32_gpiolib_register_bank(pctl, child);
>>>               if (ret) {
>>>                   of_node_put(child);
>>> +
>>> +                for (i = 0; i < pctl->nbanks; i++)
>>> +                    clk_disable_unprepare(pctl->banks[i].clk);
>>> +
>>
>> There are clk_bulk_*() functions, maybe you can use those to get rid 
>> of these loops ?
> 
> This sounds goods, but checking more in details I see that moving to the 
> 'bulk' implementation would require to move the clk information from the 
> "struct stm32_gpio_bank *banks" member to its parent "struct 
> stm32_pinctrl".
> 
> This would make the clk device information stored in a different 
> structure from the other device-related information (base address, reset 
> control, ...). It's better to keep all those information together in the 
> same struct.
> 
> As another drawback we would loose access to 'clk' from any function 
> that have 'bank' (or 'struct gpio_chip *chip') as input parameter (e.g. 
> stm32_gpio_get() called from gpiolib).
> 
> So I really prefer to keep the current implementation.

All right, I agree.

>> The rest looks good to me.

Reviewed-by: Marek Vasut <marex@...x.de>