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    SubjectRe: [linux-pm] [PATCH 2/4] PM / Loss: power loss management
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    On Thursday, May 19, 2011, Alan Stern wrote:
    > On Thu, 19 May 2011, Davide Ciminaghi wrote:
    >
    > > I'm not completely sure about this. What we wanted to do was to avoid powering
    > > down the mmc while it is physically writing data into its internal memory.
    > > If we force a sync when the power loss warning event warning happens,
    > > it is very difficult to be able to guarantee that all buffered data will be
    > > written before power actually dies. So we preferred to follow another strategy:
    > > let the mmc finish any running write operation, and then stop its request
    > > queue. If power really goes down, then we hope that the file system journal
    > > will fix things on next boot (yes, some data could get lost, but the fs should
    > > still be mountable). On the other hand, if power resumes, nothing bad should
    > > happen for user space processes.
    >
    > You could consider a totally different approach.
    >
    > Each platform will have a different set of high-power devices it wants
    > to turn off when a power-loss warning occurs. So instead of changing
    > the core PM interface, you could add a new "power_loss" notifier list.
    > Only the most critical drivers would need to listen for notifications,
    > and this could be different drivers on different platforms.

    Moreover, it would allow not only drivers, but also filesystems (for
    one example) to get notifications.

    Thanks,
    Rafael


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