Messages in this thread | | | Date | Mon, 30 Oct 2006 18:32:37 +0100 | From | "Miguel Ojeda" <> | Subject | Re: [PATCH 2.6.19-rc1 full] drivers: add LCD support |
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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).
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