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    SubjectRe: [PATCH v6 3/8] ARM: sunxi: Move the clock protection to machine hooks
    On Wed, Apr 23, 2014 at 02:39:02PM +0200, Arnd Bergmann wrote:
    > On Thursday 17 April 2014, Maxime Ripard wrote:
    > > Since we start to have a lot of clocks to protect, some of them in a few boards
    > > only, it becomes difficult to handle the clock protection without having to add
    > > per machine exceptions.
    > >
    > > Move these where they belong, in the machine definition code.
    > >
    > > Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
    >
    > I don't like the fact that these are required to be hardcoded
    > anywhere in source code.

    I agree, but that would also mean having a driver for everything that
    would need a clock: a CPU, the RAM. I'm not sure we want that either.

    > > +#include <linux/clk.h>
    > > #include <linux/init.h>
    > > #include <linux/of_platform.h>
    > >
    > > @@ -19,9 +20,17 @@
    > >
    > > static void __init sun4i_dt_init(void)
    > > {
    > > + struct clk *clk;
    > > +
    > > sunxi_setup_restart();
    > >
    > > of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
    > > +
    > > + /* Make sure the clocks we absolutely need are enabled */
    > > + /* DDR clock */
    > > + clk = clk_get(NULL, "pll5_ddr");
    > > + if (!IS_ERR(clk))
    > > + clk_prepare_enable(clk);
    > > }
    >
    > Isn't there already DT syntax to do the same? If not, should there be?

    I don't think there is, and I gave some thought about it too. But
    something a la regulator-always-on wouldn't work with clocks with
    multiple outputs (like pll5), because you might need to leave only one
    of the output enabled, but not the others, and I couldn't think of a
    nice way to do so.

    If you have one, I'd be happy to implement it.

    Maxime

    --
    Maxime Ripard, Free Electrons
    Embedded Linux, Kernel and Android engineering
    http://free-electrons.com
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