[Mesa-dev] [PATCH 1/4] xa: handle solid-fill src/mask

[Brian Paul]

On 04/03/2014 08:13 AM, Rob Clark wrote:
> On Thu, Apr 3, 2014 at 10:07 AM, Brian Paul <brianp at vmware.com> wrote:
>> On 04/02/2014 11:17 PM, Thomas Hellstrom wrote:
>>>
>>> On 04/01/2014 05:04 PM, Rob Clark wrote:
>>>>
>>>> From: Rob Clark <robclark at freedesktop.org>
>>>>
>>>> Add support to property handle solid-fill src and/or mask.  Without this
>>>> we fallback to sw a lot for common things like text rendering.
>>>>
>>>> Signed-off-by: Rob Clark <robclark at freedesktop.org>
>>>> ---
>>>>    src/gallium/state_trackers/xa/xa_composite.c |  88 ++++----
>>>>    src/gallium/state_trackers/xa/xa_priv.h      |   7 +-
>>>>    src/gallium/state_trackers/xa/xa_renderer.c  | 289
>>>> ++++++++++++++++-----------
>>>>    src/gallium/state_trackers/xa/xa_tgsi.c      |  31 ++-
>>>>    4 files changed, 242 insertions(+), 173 deletions(-)
>>>
>>>
>>> Rob,
>>> While testing this patch it looks like we sometimes set two samplers,
>>> and the first one is NULL.
>>> The SVGA driver asserts on that condition.
>>> We might need to move the active sampler to the first entry in that
>>> case, and adjust tex coords and shader accordingly.
>>>
>>> I'll discuss with BrianP.
>>
>>
>> I think the root problem is a disagreement between texture samplers and
>> sampler views.  If a texture sampler is non-null, the corresponding sampler
>> view be should be non-null too, and vice versa.
>>
>> We're tripping over an assertion when a a sampler view is non-null but the
>> corresponding sampler is NULL.
>
> Right..
>
> Well, I think it would be not to hard to make things always start with
> SAMP[0], which would avoid this.  But I am pretty fuzzy about whether
> it is the driver or state tracker that is wrong here..  I started with
> the assumption that it was just a freedreno bug, but if it causes
> problem w/ vmware too, then maybe the state tracker is at fault.

I believe the general policy is that drivers can assume they're being 
passed valid input and consistent state.  State trackers shouldn't pass 
inconsistent state to drivers.

In this case, the number of texture samplers and sampler views is 
inconsistent.  The drivers could examine the current shader to determine 
which samplers/views are actually used (which might be a subset of what 
was specified by the state tracker).  But that's extra work that all 
drivers would have to implement.  It seems much more economical to take 
care of this in the state trackers.

-Brian