linux-kernel - Re: [PATCH 1/7] mmc: sdhci: fix base clock usage in preset value

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Date:   Wed, 15 Apr 2020 18:28:39 +0200
From:   Michał Mirosław <mirq-linux@...e.qmqm.pl>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Ulf Hansson <ulf.hansson@...aro.org>,
        Kevin Liu <kliu5@...vell.com>,
        Michal Simek <michal.simek@...inx.com>,
        Suneel Garapati <suneel.garapati@...inx.com>,
        linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/7] mmc: sdhci: fix base clock usage in preset value

On Wed, Apr 15, 2020 at 03:25:52PM +0300, Adrian Hunter wrote:
> On 2/04/20 2:54 pm, Michał Mirosław wrote:
> > Fixed commit added an unnecessary read of CLOCK_CONTROL. The value read
> > is overwritten for programmable clock preset, but is carried over for
> > divided clock preset. This can confuse sdhci_enable_clk() if the register
> > has enable bits set for some reason at time time of clock calculation.
> > value to be ORed with enable flags. Remove the read.
> 
> The read is not needed, but drivers usually manage the enable bits,
> especially disabling the clock before changing the frequency.  What driver
> is it?

Hopefully no driver requires this. It's just removing a trap.

Best Regards,
Michał Mirosław