linux-kernel - Re: [PATCH 1/2] soc: samsung: exynos-pmu: instantiate clkout driver as MFD

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Message-ID: <32d3faaf-1631-3ebe-6d73-fe565c39639d@kernel.org>
Date:   Fri, 23 Oct 2020 13:34:19 +0200
From:   Sylwester Nawrocki <snawrocki@...nel.org>
To:     Krzysztof Kozlowski <krzk@...nel.org>,
        Tomasz Figa <tomasz.figa@...il.com>, linux-clk@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Sylwester Nawrocki <s.nawrocki@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, Kukjin Kim <kgene@...nel.org>,
        linux-samsung-soc@...r.kernel.org,
        Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: [PATCH 1/2] soc: samsung: exynos-pmu: instantiate clkout driver
 as MFD

Hi,

On 10/1/20 18:56, Krzysztof Kozlowski wrote:
> The Exynos clock output (clkout) driver uses same register address space
> (Power Management Unit address space) as Exynos PMU driver and same set
> of compatibles.  It was modeled as clock provider instantiated with
> CLK_OF_DECLARE_DRIVE().
> 
> This however brings ordering problems and lack of probe deferral,
> therefore clkout driver should be converted to a regular module and
> instantiated as a child of PMU driver to be able to use existing
> compatibles and address space.

It might have been cleaner to have the CLKOUT device as a PMU subnode in DT, 
then device instantiation would be already covered by devm_of_platform_populate().
But it gets a bit complicated to make such a change in a backward compatible way.

I have tested both patches on Trats2, where CLKOUT provides master clock for
the audio codec.

Reviewed-by: Sylwester Nawrocki <s.nawrocki@...sung.com>
Tested-by: Sylwester Nawrocki <s.nawrocki@...sung.com>
 

> @@ -128,6 +134,11 @@ static int exynos_pmu_probe(struct platform_device *pdev)
>   
>   	platform_set_drvdata(pdev, pmu_context);
>   
> +	ret = devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE, exynos_pmu_devs,
> +				   ARRAY_SIZE(exynos_pmu_devs), NULL, 0, NULL);
> +	if (ret)
> +		return ret;
> +
>   	if (devm_of_platform_populate(dev))
>   		dev_err(dev, "Error populating children, reboot and poweroff might not work properly\n");