linux-kernel - Re: [PATCH] ARM: sti: stih410-clocks: Add PROC

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Message-ID: <20161026085141.GJ8574@dell>
Date:   Wed, 26 Oct 2016 09:51:41 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Peter Griffin <peter.griffin@...aro.org>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kernel@...inux.com, patrice.chotard@...com,
        devicetree@...r.kernel.org
Subject: Re: [PATCH] ARM: sti: stih410-clocks: Add PROC_STFE as a critical
 clock

> > > If the clock is enabled when Linux boots, the Linux clock framework *needs*
> > > to assume the hardware may have been used in previous boot stages, and it should
> > > not attempt to disable the clock.
> > 
> > None of the boot loaders we use do this.
> 
> But the Linux kernel isn't just used by us. It is not uncommon for STB
> bootloaders to get information from the frontend as part of the boot process. 

Okay, this is the clincher.  Since we need to support non-standard
bootloaders, it's difficult to guarantee that the clock will be
disabled at boot.  For this reason, I believe that we can call this a
critical clock.

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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