Re: [PATCH v3 2/2] pinctrl: samsung: support a bus clock

From: Krzysztof Kozlowski <krzk@kernel.org>
To: "André Draszik" <andre.draszik@linaro.org>,
	"Tudor Ambarus" <tudor.ambarus@linaro.org>,
	"Sylwester Nawrocki" <s.nawrocki@samsung.com>,
	"Alim Akhtar" <alim.akhtar@samsung.com>,
	"Linus Walleij" <linus.walleij@linaro.org>,
	"Rob Herring" <robh@kernel.org>,
	"Conor Dooley" <conor+dt@kernel.org>,
	"Tomasz Figa" <tomasz.figa@gmail.com>,
	"Peter Griffin" <peter.griffin@linaro.org>
Cc: Will McVicker <willmcvicker@google.com>,
	Sam Protsenko <semen.protsenko@linaro.org>,
	kernel-team@android.com, linux-arm-kernel@lists.infradead.org,
	linux-samsung-soc@vger.kernel.org, linux-gpio@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 2/2] pinctrl: samsung: support a bus clock
Date: Fri, 3 May 2024 11:13:06 +0200	[thread overview]
Message-ID: <c39eab66-4e78-4f24-bcaf-003161b38ed0@kernel.org> (raw)
In-Reply-To: <c4c73732595b067369a6c8d71508d54358962552.camel@linaro.org>

On 02/05/2024 12:41, André Draszik wrote:
> On Thu, 2024-05-02 at 09:46 +0200, Krzysztof Kozlowski wrote:
>> On 02/05/2024 09:41, Tudor Ambarus wrote:
>>>>  
>>>> @@ -223,6 +268,13 @@ static void exynos_irq_release_resources(struct irq_data *irqd)
>>>>  	shift = irqd->hwirq * bank_type->fld_width[PINCFG_TYPE_FUNC];
>>>>  	mask = (1 << bank_type->fld_width[PINCFG_TYPE_FUNC]) - 1;
>>>>  
>>>> +	if (clk_enable(bank->drvdata->pclk)) {
>>>> +		dev_err(bank->gpio_chip.parent,
>>>> +			"unable to enable clock for deconfiguring pin %s-%lu\n",
>>>> +			bank->name, irqd->hwirq);
>>>> +		return;
>>>
>>> but here we just print an error. I guess that for consistency reasons it
>>> would be good to follow up with a patch and change the return types of
>>> these methods and return the error too when the clock enable fails.
>>
>> That's a release, so usually void callback. The true issue is that we
>> expect release to always succeed, I think.
>>
>> This points to issue with this patchset: looks like some patchwork all
>> around the places having register accesses. But how do you even expect
>> interrupts and pins to work if entire pinctrl block is clock gated?
> 
> I was initially thinking the same, but the clock seems to be required for
> register access only, interrupts are still being received and triggered
> with pclk turned off as per my testing.

Probably we could simplify this all and keep the clock enabled always,
when device is not suspended. Toggling clock on/off for every pin change
is also an overhead. Anyway, I merged the patches for now, because it
addresses real problem and seems like one of reasonable solutions.

Best regards,
Krzysztof

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