[PATCH V2 13/16] OMAP: hsmmc: implement clock switcher
Tony Lindgren
tony at atomide.com
Thu May 12 06:37:23 EDT 2011
* Adrian Hunter <adrian.hunter at nokia.com> [110506 02:13]:
> From: Andy Shevchenko <ext-andriy.shevchenko at nokia.com>
>
> There are 3 new platform data methods which should help us to do a clock
> switching when notification is happened or request is started.
>
> The purpose of the patch is to avoid high frequency of MMC controller on low
> OPPs due to an HW bug in OMAP 3630.
...
> +static int hsmmc_clk_notifier(struct notifier_block *nb, unsigned long event,
> + void *data)
> +{
> + struct cpufreq_freqs *freqs = data;
> + unsigned int threshold = 400000; /* between opp1 and opp2 */
> +
> + switch (event) {
> + case CPUFREQ_PRECHANGE:
> + if (freqs->new < threshold && freqs->old >= threshold) {
> + /* opp2 -> opp1 */
> + hsmmc_max_freq = HSMMC_MAX_FREQ >> 1;
> +
> + /* Timeout is 1 sec */
> + if (!wait_event_timeout(hsmmc_max_freq_wq,
> + hsmmc_max_freq_ok(),
> + msecs_to_jiffies(1000)))
> + pr_err("MMC violates maximum frequency "
> + "constraint\n");
> + }
> + break;
> + case CPUFREQ_POSTCHANGE:
> + if (freqs->old < threshold && freqs->new >= threshold) {
> + /* opp1 -> opp2 */
> + hsmmc_max_freq = HSMMC_MAX_FREQ;
> + }
> + break;
> + default:
> + break;
> + }
> +
> + return NOTIFY_DONE;
> +}
I think the cpufreq notifier code should be in the driver, the platform
init code should just prepare things for the driver.
Regards,
Tony
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