On Wed, 2010-07-21 at 14:01 +0200, MichaÅ Nazarewicz wrote:
What you are asking for is:
cma=a=100M cma_map=*/*=a
All devices will share the same region so that "if the video driver isn't
using the memory" then "something else can use it". (please excuse me quoting
you, it was stronger then me ;) ).
Ok ..
Driver has to little information to say whether it really stopped using
memory. Maybe the next call will be to allocate buffers for frames and
initialise the chip? Sure, some âgood enoughâ defaults can be provided
(and the framework allows that) but still platform architect might need
more power.
I think your talking more about optimization .. You can take that into
account ..
> (btw, these strings your creating yikes, talk about confusing ..)
They are not that scary really. Let's look at cma:
a=10M;b=10M
Split it on semicolon:
a=10M
b=10M
and you see that it defines two regions (a and b) 10M each.
I think your assuming a lot .. I've never seen the notation before I
wouldn't assuming there's regions or whatever ..
As of cma_map:
camera,video=a;jpeg,scaler=b
Again split it on semicolon:
camera,video=a
jpeg,scaler=b
Now, substitute equal sign by "use(s) region(s)":
camera,video use(s) region(s): a
jpeg,scaler use(s) region(s): b
No black magic here. ;)
It way too complicated .. Users (i.e. not programmers) has to use
this ..
>> One of the purposes of the CMA framework is to make it let device
>> drivers completely forget about the memory management and enjoy
>> a simple API.
>
> The driver, and it's maintainer, are really the best people to know how
> much memory they need and when it's used/unused. You don't really want
> to architect them out.
This might be true if there is only one device but even then it's not
always the case. If many devices need physically-contiguous memory
there is no way for them to communicate and share memory. For best
performance someone must look at them and say who gets what.
How do you think regular memory allocation work? I mean there's many
devices that all need different amounts of memory and they get along.
Yet your saying it's not possible .