linux-kernel - Re: [PATCH v2] ARM: tegra: enforce PM requirement

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Date:   Tue, 26 Feb 2019 09:13:08 +0000
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Sameer Pujar <spujar@...dia.com>
Cc:     digetx@...il.com, jhogan@...nel.org, thierry.reding@...il.com,
        jonathanh@...dia.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] ARM: tegra: enforce PM requirement

On Tue, Feb 26, 2019 at 01:55:37PM +0530, Sameer Pujar wrote:
> The requirement for this came while adding runtime PM support for HDA
> driver. There were concerns about driver explicitly handling !PM case.
> In general, drivers need to handle !PM case with work arounds for
> managing clocks and power explicitly, which is not really necessary
> when PM support on tegra is in good shape. In fact ARM 64-bit Tegra
> platforms enforce PM support and there is no reason why this cannot be
> done for 32-bit.
> 
> More details with regards to above can be found in following patch,
> http://patchwork.ozlabs.org/patch/1036645/
> 
> This patch selects PM unconditionally and drivers can rely on runtime
> PM framework for clock and power management.

What if the drivers are re-used on another SoC IP?  Doesn't this lead
to unexpected failures?

If you want to do this, maybe also make those drivers depend on PM as
well?

> Signed-off-by: Sameer Pujar <spujar@...dia.com>
> Reviewed-by: Thierry Reding <treding@...dia.com>
> Reviewed-by: Jonathan Hunter <jonathanh@...dia.com>
> ---
>  arch/arm/mach-tegra/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm/mach-tegra/Kconfig b/arch/arm/mach-tegra/Kconfig
> index 7f3b83e..51a8fa3 100644
> --- a/arch/arm/mach-tegra/Kconfig
> +++ b/arch/arm/mach-tegra/Kconfig
> @@ -10,6 +10,7 @@ menuconfig ARCH_TEGRA
>  	select HAVE_ARM_SCU if SMP
>  	select HAVE_ARM_TWD if SMP
>  	select PINCTRL
> +	select PM
>  	select PM_OPP
>  	select ARCH_HAS_RESET_CONTROLLER
>  	select RESET_CONTROLLER
> -- 
> 2.7.4
> 
> 

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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