[PATCH r128] Do not disable gouraud shading for a render op

[Connor Behan]

[Fixing subject line]

On 26/11/13 05:59 AM, Alex Deucher wrote:
> On Fri, Nov 22, 2013 at 3:25 PM, Connor Behan <connor.behan at gmail.com>
> wrote:
>> The EXA Composite hooks should not overwrite any register values
>> expected by DRI. Initial testing of the EXA support revealed that
>> R128_WINDOW_XY_OFFSET is one register where we have to be careful.
>> However, it was mostly tested using glxgears which does not stress the
>> driver very much. Going through the various 3D screensavers one by one
>> reveals a bug where certain models turn green if compositing is enabled.
>>
>> It seems that if we slightly alter the values passed to R128_SETUP_CNTL
>> and R128_PM4_VC_FPU_SETUP, the 3D driver will be happy and compositing
>> will still work. The proper way would be to constantly save and restore
>> register values but this showed poor performance when dragging 3D
>> windows across the screen.
> You could always just reset the value after each draw command as part
> of the command stream.  That said, if the options don't affect the
> drawing for EXA, it should be fine.
>
Before I go back to experimenting with this, do you have a guess about
whether this would degrade performance? With an xfce desktop there are
roughly 10 composite operations per second. Counting the arguments to
BEGIN_RING, it seems that each one currently requires 70 register
writes. At first I thought there was worse performance when saving and
restoring registers because of the extra 12 writes and 6 reads that
would be needed.

Are old cards like the r128 slow at writing (with CCE) and reading
registers? Or is this mostly limited by the bus speed? And does it
depend on which register?
>
>> Signed-off-by: Connor Behan <connor.behan at gmail.com>
>> ---
>>  src/r128_exa_render.c | 6 +++---
>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/src/r128_exa_render.c b/src/r128_exa_render.c
>> index f00536e..cb9f929 100644
>> --- a/src/r128_exa_render.c
>> +++ b/src/r128_exa_render.c
>> @@ -350,7 +350,7 @@ do {                                                        \
>>                     R128_TEX_MAP_ALPHA_IN_TEXTURE |     \
>>                     R128_TEX_CACHE_LINE_SIZE_4QW);      \
>>      OUT_RING_REG(R128_SETUP_CNTL,                      \
>> -                   R128_COLOR_SOLID_COLOR |            \
>> +                   R128_COLOR_GOURAUD |                \
>>                     R128_PRIM_TYPE_TRI |                \
>>                     R128_TEXTURE_ST_MULT_W |            \
>>                     R128_STARTING_VERTEX_1 |            \
>> @@ -358,9 +358,9 @@ do {                                                        \
>>                     R128_SUB_PIX_4BITS);                \
>>      OUT_RING_REG(R128_PM4_VC_FPU_SETUP,                        \
>>                     R128_FRONT_DIR_CCW |                \
>> -                   R128_BACKFACE_CULL |                \
>> +                   R128_BACKFACE_SOLID |               \
>>                     R128_FRONTFACE_SOLID |              \
>> -                   R128_FPU_COLOR_SOLID |              \
>> +                   R128_FPU_COLOR_GOURAUD |            \
>>                     R128_FPU_SUB_PIX_4BITS |            \
>>                     R128_FPU_MODE_3D |                  \
>>                     R128_TRAP_BITS_DISABLE |            \
>> --
>> 1.8.4
>>
>> _______________________________________________
>> xorg-driver-ati mailing list
>> xorg-driver-ati at lists.x.org
>> http://lists.x.org/mailman/listinfo/xorg-driver-ati


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