On 04/29/2011 03:04 PM, Rafael J. Wysocki wrote:
> +
> +/**
> + * enable_clock - Enable a device clock.
> + * @dev: Device whose clock is to be enabled.
> + * @con_id: Connection ID of the clock.
> + */
> +static void enable_clock(struct device *dev, const char *con_id)
> +{
> + struct clk *clk;
> +
> + clk = clk_get(dev, con_id);
> + if (!IS_ERR(clk)) {
> + clk_enable(clk);
> + clk_put(clk);
> + dev_info(dev, "Runtime PM disabled, clock forced on.\n");
> + }
> +}
This doesn't make much sense to me. You're getting a clock and then
enabling it and then putting the clock? How can you be so sure that
clk_put() won't one day do some kind of lower power mode on the clock
when clk_put() is called on it? I don't think anyone does anything
today, but I don't think its safe to assume that clk_put() won't try to
forcibly shut off the clock once all clk_get() callers have clk_put().
Perhaps we should document the meaning of clk_enable() followed by
clk_put() somewhere instead?
> +
> +/**
> + * disable_clock - Disable a device clock.
> + * @dev: Device whose clock is to be disabled.
> + * @con_id: Connection ID of the clock.
> + */
> +static void disable_clock(struct device *dev, const char *con_id)
> +{
> + struct clk *clk;
> +
> + clk = clk_get(dev, con_id);
> + if (!IS_ERR(clk)) {
> + clk_disable(clk);
> + clk_put(clk);
> + dev_info(dev, "Runtime PM disabled, clock forced off.\n");
> + }
> +}
This might not be as bad, but it looks like a similar problem.
> -
> -static int platform_bus_notify(struct notifier_block *nb,
> - unsigned long action, void *data)
> -{
> - struct device *dev = data;
> - struct clk *clk;
> -
> - dev_dbg(dev, "platform_bus_notify() %ld !\n", action);
> -
> - switch (action) {
> - case BUS_NOTIFY_BIND_DRIVER:
> - clk = clk_get(dev, NULL);
> - if (!IS_ERR(clk)) {
> - clk_enable(clk);
> - clk_put(clk);
> - dev_info(dev, "runtime pm disabled, clock forced on\n");
> - }
> - break;
> - case BUS_NOTIFY_UNBOUND_DRIVER:
> - clk = clk_get(dev, NULL);
> - if (!IS_ERR(clk)) {
> - clk_disable(clk);
> - clk_put(clk);
> - dev_info(dev, "runtime pm disabled, clock forced off\n");
> - }
Ah ok I see that it's coming from here.
BTW, whatever is in linux-next is failing to compile:
drivers/base/power/clock_ops.c:391: error: 'con_id' undeclared (first
use in this function)
drivers/base/power/clock_ops.c:391: error: (Each undeclared identifier
is reported only once
drivers/base/power/clock_ops.c:391: error: for each function it appears in.)
--
Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
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