query (critical problem)

query (critical problem)

[Manish RATHI]

Hi,
I've ported linux on our chip using  linux kernel 2.4.20. On chip we have a display interface on which epson panel is attached. We've written a display driver using framebuffer driver as a upper layer.

Problem with this driver is that due to framebuffer concept we don't know when data is updated in framebuffer as this is done by application.

So we don't know when to transfer data from framebuffer to panel memory. how a driver can know this trigger.

B'coz of this we have only one option left that is always transfer data 
to dif panel from fraembuffer irrespective of any trigger.

This will create power problem.

As i understand microwindows/qt or any graphics package call open, mmap from framebuffer. Whenever it draw a line it doesn't call any driver interface.

Is there any solution?
Is there any standard interface of application with driver which tell 
that data is to be updated from frmebuffer to panel memory?

Thanks


Regards
Manish



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Re: query (critical problem)

[Antonino A. Daplas]

On Thursday 15 July 2004 20:10, Manish RATHI wrote:
> Hi,
> I've ported linux on our chip using  linux kernel 2.4.20. On chip we have a
> display interface on which epson panel is attached. We've written a display
> driver using framebuffer driver as a upper layer.
>
> Problem with this driver is that due to framebuffer concept we don't know
> when data is updated in framebuffer as this is done by application.
>
> So we don't know when to transfer data from framebuffer to panel memory.
> how a driver can know this trigger.
>
> B'coz of this we have only one option left that is always transfer data
> to dif panel from fraembuffer irrespective of any trigger.
>
> This will create power problem.
>
> As i understand microwindows/qt or any graphics package call open, mmap
> from framebuffer. Whenever it draw a line it doesn't call any driver
> interface.
>
> Is there any solution?
> Is there any standard interface of application with driver which tell
> that data is to be updated from frmebuffer to panel memory?

You can try file read and write instead of mmap to access the framebuffer.
Otherwise, you can try trapping all accesses to the memory, but this wil
involve hacking kernel internals.

Tony




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