[Mesa-dev] [PATCH] i965: setup address rounding enable bits

[Yuanhan Liu]

On Thu, Oct 13, 2011 at 09:12:09PM -0700, Ian Romanick wrote:
> On 10/12/2011 08:34 PM, Yuanhan Liu wrote:
> >The patch(based on the reading of the emulator) came from while I was
> >trying to fix the oglc pbo texImage.1PBODefaults fail. This case
> >generates a texture with the width and height equal to window's width
> >and height respectively, then try to texture it on the whole window.
> >So, it's exactly one texel for one pixel.  And, the min filter and mag
> >filter are GL_LINEAR. It runs with swrast OK, as expected. But it failed
> >with i965 driver.
> >
> >Well, you can't tell the difference from the screen, as the error is
> >quite tiny. From my digging, it seems that there are some tiny error
> >happened while getting tex address. This will break the one texel for
> >one pixel rule in this case. Thus the linear result is taken, with tiny
> >error.
> >
> >This patch would fix several oglc pbo subcase fail on both ILK, SNB and
> >IVB.
> 
> I don't know about this patch, but this led me to notice something
> else in the docs.  Starting with Sandybridge, bit 27 in dword 0 is
> "Min and Mag State Not Equal."  This is ss0.min_mag_neq in our
> structure.  The hardware docs say that this bit must be set to 0 if
> the min and mag filter state are not the same, min and mag U round
> modes are not the same, min and mag V round modes are not the same,
> or min and mag R round modes are not the same.  I can't see that
> this bit is set anywhere in the driver.