On Mon, Dec 5, 2011 at 5:50 PM, Mark Brown
<broonie@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> Enable and disable the clocks to the SPI controller using runtime PM. This
> serves the dual purpose of reducing power consumption a little and letting
> the core know when the device is idle.
(...)
> +#ifdef CONFIG_PM_RUNTIME
> +static int s3c64xx_spi_runtime_suspend(struct device *dev)
> +{
> + struct spi_master *master = spi_master_get(dev_get_drvdata(dev));
> + struct s3c64xx_spi_driver_data *sdd = spi_master_get_devdata(master);
> +
> + clk_disable(sdd->clk);
> + clk_disable(sdd->src_clk);
> +
> + return 0;
> +}
> +
> +static int s3c64xx_spi_runtime_resume(struct device *dev)
> +{
> + struct spi_master *master = spi_master_get(dev_get_drvdata(dev));
> + struct s3c64xx_spi_driver_data *sdd = spi_master_get_devdata(master);
> +
> + clk_enable(sdd->src_clk);
> + clk_enable(sdd->clk);
> +
> + return 0;
> +}
> +#endif /* CONFIG_PM_RUNTIME */
This is similar to how I'm doing things in my drivers so this looks
good to me, Acked-by.
Just wanted to mention that I had this discussion with Magnus Damm
about how they do this in shmobile: in there their central runtime PM
policy in arch/arm/mach-shmobile/pm_runtime.c adds in the
pm_clk_notifier from drivers/base/power/clock_ops.c to gate/ungate
the clocks centrally acting on bus notifiers without any per-driver
hooks like these.
I clearly see that in this platform it's *not* going to work since
for this one driver atleast, there are two clocks, not just one,
that need to be managed for the device.
So I guess that some platforms will do central clock
management and some will do driver-local management.
I fear for the day one of these devices turn up in two platforms:
one using central clock management and one using
distributed clock management ...
Yours,
Linus Walleij
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