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    SubjectRe: [PATCH 2.6.19-rc1 full] drivers: add LCD support
    On 10/30/06, Paulo Marques <pmarques@grupopie.com> wrote:
    >
    > No, this is not the sequence I thought of at all. I don't remember the
    > exact API functions you need to call (I have to read LDD3 again ;), but
    > if the hardware supports it, there must be a way. The plan is something
    > like:
    >
    > - at mmap time you return a pointer to something that is not actually
    > mapped, and do nothing else
    >
    > - when userspace actually writes to that area, you get a page fault,
    > and nopage is called. At this point you map the page, and set the dirty
    > state. All other writes from userspace until the timer completes are
    > done without faulting.
    >
    > - when the timer completes, you unmap the page so that the next access
    > will generate a fault again
    >
    > As I said, I don't remember the exact details, but this should be doable.
    >

    Yes, I get the idea, you mean to "unmap" the page but don't remove the
    vma so a page fault is raised and nopage() op must be called again.
    May it decrease performance? (Linux /you must take care of a page
    fault calling nopage() each time you write/refresh the LCD, then
    actually use it).

    Miguel Ojeda
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