[Intel-gfx] [PATCH] drm/i915/bdw: Populate lrc with aliasing ppgtt if required

[Daniel Vetter]

Ok, things start to dawn upon me - let's blame it on the lack of
decent coffee here ;-) I mixed up USES_PPGTT with USES_FULL_PPGTT
(again) so didn't realize that execlist works with just aliasing
ppgtt. So  I guess there's still room to clean up these macros a bit,
maybe do an s/USES_PPGTT/USES_HW_PPGTT/ or so, to make it clear that
this isn't about multiple address spaces.

I do like Damien's suggestion though since imo depending upon runtime
state is less fragile than rechecking driver option.
-Daniel

On Mon, Aug 18, 2014 at 6:49 PM, Damien Lespiau
<damien.lespiau at intel.com> wrote:
> On Mon, Aug 18, 2014 at 03:54:02PM +0100, Thomas Daniel wrote:
>> A previous commit broke aliasing PPGTT for lrc, resulting in a kernel oops
>> on boot. Add a check so that is full PPGTT is not in use the context is
>> populated with the aliasing PPGTT.
>>
>> Issue: VIZ-4278
>> Signed-off-by: Thomas Daniel <thomas.daniel at intel.com>
>> ---
>>  drivers/gpu/drm/i915/intel_lrc.c |    7 +++++++
>>  1 file changed, 7 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
>> index c096b9b..79a6b91 100644
>> --- a/drivers/gpu/drm/i915/intel_lrc.c
>> +++ b/drivers/gpu/drm/i915/intel_lrc.c
>> @@ -1452,12 +1452,19 @@ static int
>>  populate_lr_context(struct intel_context *ctx, struct drm_i915_gem_object *ctx_obj,
>>                   struct intel_engine_cs *ring, struct intel_ringbuffer *ringbuf)
>>  {
>> +     struct drm_device *dev = ring->dev;
>> +     struct drm_i915_private *dev_priv = dev->dev_private;
>>       struct drm_i915_gem_object *ring_obj = ringbuf->obj;
>>       struct i915_hw_ppgtt *ppgtt = ctx->ppgtt;
>
> It's a bit weird to leave ppgtt initialized here when you're going to
> always override it below.
>
>>       struct page *page;
>>       uint32_t *reg_state;
>>       int ret;
>>
>> +     if (USES_FULL_PPGTT(dev))
>> +             ppgtt = ctx->ppgtt;
>> +     else
>> +             ppgtt = dev_priv->mm.aliasing_ppgtt;
>> +
>
> The patch drom daniel you mention removes the usage of USES_FULL_PPGTT()
> to directly test ctx->ppgtt. You may want to reproduce that here ie.
>
>         ppgtt = ctx->ppgtt;
>         if (!ppgtt)
>                 ppgtt = dev_priv->mm.aliasing_ppgtt;
>
> doesn't really matter either way I guess, but can we at least not set
> then always override ppgtt?
>
> Thanks,
>
> --
> Damien
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch