[Mesa-dev] [PATCH 08/16] freedreno: a2xx: enable early-Z testing

[Jonathan marek]

Hi,

I didn't verify it, but both r600 and a3xx disable earlyZ when alpha 
test is enabled, so this is almost certainly right.

We don't need to worry about the shader writing Z, it is not part of 
OpenGL ES 2.0 and not implemented by the driver (although the hardware 
should allow it).

Why should we need to check if the shader does discards?

On 12/19/2018 01:05 PM, Eric Anholt wrote:
> Jonathan Marek <jonathan at marek.ca> writes:
> 
>> Enable earlyZ when alpha test is disabled.
>>
>> Signed-off-by: Jonathan Marek <jonathan at marek.ca>
>> ---
>>   src/gallium/drivers/freedreno/a2xx/fd2_zsa.c | 3 ++-
>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/src/gallium/drivers/freedreno/a2xx/fd2_zsa.c b/src/gallium/drivers/freedreno/a2xx/fd2_zsa.c
>> index 64b31b677b..d3c19b4450 100644
>> --- a/src/gallium/drivers/freedreno/a2xx/fd2_zsa.c
>> +++ b/src/gallium/drivers/freedreno/a2xx/fd2_zsa.c
>> @@ -49,7 +49,8 @@ fd2_zsa_state_create(struct pipe_context *pctx,
>>   		A2XX_RB_DEPTHCONTROL_ZFUNC(cso->depth.func); /* maps 1:1 */
>>   
>>   	if (cso->depth.enabled)
>> -		so->rb_depthcontrol |= A2XX_RB_DEPTHCONTROL_Z_ENABLE;
>> +		so->rb_depthcontrol |= A2XX_RB_DEPTHCONTROL_Z_ENABLE |
>> +			COND(!cso->alpha.enabled, A2XX_RB_DEPTHCONTROL_EARLY_Z_ENABLE);
> 
> Why when alpha test is disabled?  Should you also be checking if the
> shader does discards?  How about if the shader writes Z, is anything
> preventing early Z then?
>