Re: [PATCH 2.6.20 1/1] fbdev,mm: hecuba/E-Ink fbdev driver

From: Jaya Kumar
Date: Tue Feb 20 2007 - 01:11:48 EST

On 2/19/07, Paul Mundt <lethal@xxxxxxxxxxxx> wrote:
On Mon, Feb 19, 2007 at 11:13:04PM -0500, Jaya Kumar wrote:
> Ok. Here's what I'm thinking for abstracting this:
> fbdev drivers would setup fb_mmap with their own_mmap as usual. In
> own_mmap, they would do what they normally do and setup a vm_ops. They
> are free to have their own nopage handler but would set the
> page_mkwrite handler to be fbdev_deferred_io_mkwrite().

The vast majority of drivers do not implement ->fb_mmap(), and with
proper abstraction, this should be something that's possible as a direct
alternative to drivers/video/fbmem.c:fb_mmap() for the people that want
it. Of course it's just as easy to do something like the sbuslib.c route
and then have drivers set their ->fb_mmap() from that too.

I was thinking about having that fb_mmap replacement too. But then I
got worried because that generic implementation of nopage/etc would
need to handle whether the driver's fb memory was vmalloced, kmalloced
or a mixture if some do that. So I figured let's aim low and just pull
in the core part that does the setup and page tracking stuff. I hope
that's okay.

That works for me, though I'd prefer for struct page_list to be done with
a scatterlist, then it's trivial to setup from the workqueue context
without having to shuffle things around.

Ok. Will check out when implementing.

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