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Bug in driver (Android SGS 2 I9100)

Laurent Mallet
Note: This was originally posted on 3rd June 2011 at http://forums.arm.com

Hello,

I'm an Android dev and have bought the SGS 2 I9100 (GPU Mali 400). I have developed a tool called
GPUBench and tested on this device and found a bug which cause many artefact.

In shader, sin & cos are valid (or correct) between -6.14 and 6.14; when angle is important, result are
false.

I have created and apk which show the problem:
And there is code source:
How fix driver on Android ? Is it the work of ARM or Samsung ?

Thanks

twitter: ellis2323
mail: laurent.mallet at_ gmail.com
Parents
  • Note: This was originally posted on 3rd June 2011 at http://forums.arm.com

    Hello Doug,

    You have the code source, change to mediump doesn't fix anything. Sin/Cos aren't correct after 3 round => time value is near from 19. I haven't seen any restriction for angle values.
    What i'm trying todo is a simple rotozoom. It works on any mobile GPU but not the Mali400.

    I have written a bench tool which is a port a shadertoy and it uses intensively sin and cos in value greater than 20...
    You can try it: gpubench Many effects seems crappy on mali 400. if you add mod(angle, 6.29), the result is ok. So i'm sure that there is a problem which is not precision related.

    My code has been tested on many mobile gpus:
    - powervr 530/535 (iphone 3GS / iphone4 / ipad 1)
    - powervr 540 (SGS / Galaxy Tab)
    - powervr 543 (ipad2)
    - andreno 200 (N1)
    - andreno 205 (HTC Desire HD)
    - Geforce ULP (Xoom, LG Optimus 2X...)
    ...
Reply
  • Note: This was originally posted on 3rd June 2011 at http://forums.arm.com

    Hello Doug,

    You have the code source, change to mediump doesn't fix anything. Sin/Cos aren't correct after 3 round => time value is near from 19. I haven't seen any restriction for angle values.
    What i'm trying todo is a simple rotozoom. It works on any mobile GPU but not the Mali400.

    I have written a bench tool which is a port a shadertoy and it uses intensively sin and cos in value greater than 20...
    You can try it: gpubench Many effects seems crappy on mali 400. if you add mod(angle, 6.29), the result is ok. So i'm sure that there is a problem which is not precision related.

    My code has been tested on many mobile gpus:
    - powervr 530/535 (iphone 3GS / iphone4 / ipad 1)
    - powervr 540 (SGS / Galaxy Tab)
    - powervr 543 (ipad2)
    - andreno 200 (N1)
    - andreno 205 (HTC Desire HD)
    - Geforce ULP (Xoom, LG Optimus 2X...)
    ...
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