Hi Linus,
On Wed, Nov 3, 2010 at 11:22 AM, Linus Walleij
<linus.walleij@xxxxxxxxxxxxxx> wrote:
...
> +static void mmc_host_clk_gate_delayed(struct mmc_host *host)
> +{
> + unsigned long tick_ns;
> + unsigned long freq = host->ios.clock;
> + unsigned long flags;
> + int users;
> +
> + if (!freq) {
> + pr_err("%s: frequency set to 0 in disable function, "
> + "this means the clock is already disabled.\n",
> + mmc_hostname(host));
> + return;
> + }
> + /*
> + * New requests may have appeared while we were scheduling,
> + * then there is no reason to delay the check before
> + * clk_disable().
> + */
> + spin_lock_irqsave(&host->clk_lock, flags);
> + users = host->clk_requests;
> + /*
> + * Delay n bus cycles (at least 8 from MMC spec) before attempting
> + * to disable the MCI block clock. The reference count
> + * may have gone up again after this delay due to
> + * rescheduling!
> + */
> + if (!users) {
> + spin_unlock_irqrestore(&host->clk_lock, flags);
> + tick_ns = DIV_ROUND_UP(1000000000, freq);
> + ndelay(host->clk_delay * tick_ns);
> + } else {
> + /* New users appeared while waiting for this work */
> + host->clk_pending_gate = false;
> + spin_unlock_irqrestore(&host->clk_lock, flags);
> + return;
> + }
> + spin_lock_irqsave(&host->clk_lock, flags);
> + if (!host->clk_requests) {
> + spin_unlock_irqrestore(&host->clk_lock, flags);
What if mmc_host_clk_ungate() is invoked (and completely executes) at
this point (as a result of a new mmc request) ?
> + /* this will set host->ios.clock to 0 */
> + mmc_gate_clock(host);
Will this clock gating not disrupt that new mmc request ?
Or am I missing something ?
> + spin_lock_irqsave(&host->clk_lock, flags);
> + pr_debug("%s: gated MCI clock\n",
> + mmc_hostname(host));
> + }
> + host->clk_pending_gate = false;
What is clk_pending_gate used for (I can only see it being assigned values) ?
Thanks,
Ohad.
(PS sorry for the belated posting of these questions)
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