Hardware acceleration for blit/fillrect in GMA-HD driver(i915)

Hardware acceleration for blit/fillrect in GMA-HD driver(i915)

[Neeraj N T]

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Hi All,

I am in need to check whether the graphics driver for GMA-HD( i915) 
provides hardware accelerated graphics functions.

While analyzing the  code of  i915 driver I found that the graphic 
functions like 'blit' and 'fillrect' are mapped to functions like 
'cfb_imageblit', 'cfb_fillrect'. Looking into 'cfb_xxxx' implementation, 
I understood that ultimately all of them  puts image data(bit map) to a 
memory address. According to my expectation,  this address should 
correspond to the video memory/graphics
memory of the graphics hardware(So that it could be argued that hardware 
acceleration is used for the above mentioned functions). But it was 
observed that, the memory was kmalloc()'ed with FLAGS GFP_KERNEL. From 
the observation, can I conclude
that the 'blit'/'fillrect' functions of i915 driver doesn't  use  
hardware  acceleration at all?  Could  anybody  suggest  me  any  other 
i915 functions for accessing 'blit'/'fillrect' functionalities with 
hardware acceleration?

Please correct me wherever I am wrong.

Thanks,

Neeraj N.T




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Re: Hardware acceleration for blit/fillrect in GMA-HD driver(i915)

[Chris Wilson]

On Wed, 02 Feb 2011 17:01:14 +0530, Neeraj N T <neerajnt@tataelxsi.co.in> wrote:
> Hi All,
> 
> I am in need to check whether the graphics driver for GMA-HD( i915) 
> provides hardware accelerated graphics functions.

No, the i915.ko does not provide an accelerated fbdev. It's a very low
priority project since we have very good acceleration layers in userspace,
and the emphasis for fbcon is to make sure that panics work. Even if we
accidentally set to the GPU.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre

Re: Hardware acceleration for blit/fillrect in GMA-HD driver(i915)

[Neeraj N T]

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Hi,
Thanks for replying.
By  ' acceleration layers in user space ' are you referring to graphics 
libraries like DirectFB,OpenGL..etc..?
Could you please shed some light into how they use the hardware 
acceleration ? ( Like are they mmap'ing to
 a graphics hardware (GMA-HD) specific video memory?)

Neeraj N.T

Chris Wilson wrote:
> On Wed, 02 Feb 2011 17:01:14 +0530, Neeraj N T <neerajnt@tataelxsi.co.in> wrote:
>   
>> Hi All,
>>
>> I am in need to check whether the graphics driver for GMA-HD( i915) 
>> provides hardware accelerated graphics functions.
>>     
>
> No, the i915.ko does not provide an accelerated fbdev. It's a very low
> priority project since we have very good acceleration layers in userspace,
> and the emphasis for fbcon is to make sure that panics work. Even if we
> accidentally set to the GPU.
> -Chris
>
>   



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Re: Hardware acceleration for blit/fillrect in GMA-HD driver(i915)

[Chris Wilson]

On Wed, 02 Feb 2011 18:14:37 +0530, Neeraj N T <neerajnt@tataelxsi.co.in> wrote:
> Hi,
> Thanks for replying.
> By  ' acceleration layers in user space ' are you referring to graphics 
> libraries like DirectFB,OpenGL..etc..?
> Could you please shed some light into how they use the hardware 
> acceleration ? ( Like are they mmap'ing to
>  a graphics hardware (GMA-HD) specific video memory?)

The hardware resources are managed by the kernel, which presents the GEM
api to userspace: http://lwn.net/Articles/283798/ . And the chipset
documentation can be found at http://intellinuxgraphics.org/ .

But it does sound like you are trying to reinvent the wheel and tie
yourself into a single and very limited platform...
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre