mirror of https://gitee.com/openkylin/linux.git
c4d770d724
Aggressive power management is suitable when saving power is essential. At request inactivity timeout, aka pm runtime autosuspend timeout, the card will be suspended. Once a new request arrives, the card will be re-initalized and thus the first request will suffer from a latency. This latency is card-specific, experiments has shown in general that SD-cards has quite poor initialization time, around 300ms-1100ms. eMMC is not surprisingly far better but still a couple of hundreds of ms has been observed. Except for the request latency, it is important to know that suspending the card will also prevent the card from executing internal house-keeping operations in idle mode. This could mean degradation in performance. To use this feature make sure the request inactivity timeout is chosen carefully. This has not been done as a part of this patch. Enable this feature by using host cap MMC_CAP_AGGRESSIVE_PM and by setting CONFIG_MMC_UNSAFE_RESUME. Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> Signed-off-by: Chris Ball <cjb@laptop.org> |
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