linux-kernel - Re: [PATCH] spi: bcm63xx-hsspi: Really keep pll clk enabled

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Message-ID: <20200302123859.GC4166@sirena.org.uk>
Date:   Mon, 2 Mar 2020 12:38:59 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     f.fainelli@...il.com, bcm-kernel-feedback-list@...adcom.com,
        jonas.gorski@...il.com, linux-spi@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] spi: bcm63xx-hsspi: Really keep pll clk enabled

On Fri, Feb 28, 2020 at 10:38:38PM +0100, Christophe JAILLET wrote:

> To be honest, I don't see why we need to keep pll clk, or hsspi clk
> enabled during the lifetime of the driver. My understanding of the code is
> that it is only used to get the 'speed_hz' value in the probe function.
> This value is never refreshed afterwards.
> I don't see the point in enabling/disabling the clks. I think that they
> both could be disabled in the probe function, without the need to keep
> track in the bcm63xx_hsspi structure, neither during pm cycles or the
> remove fucntion.

If the device has a clock there's a good chance it's needed for the
device to operate and that disabling it will save a little power when
the device isn't doing anything.

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