Re: [PATCH v3 24/37] drm/i915: set num_fence_regs to 0 if there is no aperture

Daniele Ceraolo Spurio
2019-08-13T21:22:12Z

On 8/9/19 3:46 PM, Daniele Ceraolo Spurio wrote:
>
>
> On 8/9/19 3:26 PM, Matthew Auld wrote:
>> From: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
>>
>> We can't fence anything without aperture.
>
> When I wrote this patch (before LMEM was in the picture) mappable
> aperture was supposed to only be missing in headless scenarios so I
> didn't consider the display case. Do we still need/use fences for direct
> access from display HW to LMEM? if so, we should drop this.
>
> Daniele
>

Chris confirmed there is currently no use-case from the display side, so
we can keep this.

Daniele

>>
>> Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
>> Signed-off-by: Stuart Summers <stuart.summers@intel.com>
>> Cc: Matthew Auld <matthew.auld@intel.com>
>> ---
>>   drivers/gpu/drm/i915/i915_gem_fence_reg.c | 6 ++++--
>>   1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_gem_fence_reg.c
>> b/drivers/gpu/drm/i915/i915_gem_fence_reg.c
>> index bcac359ec661..bb7d9321cadf 100644
>> --- a/drivers/gpu/drm/i915/i915_gem_fence_reg.c
>> +++ b/drivers/gpu/drm/i915/i915_gem_fence_reg.c
>> @@ -808,8 +808,10 @@ void i915_ggtt_init_fences(struct i915_ggtt *ggtt)
>>       detect_bit_6_swizzle(i915);
>> -    if (INTEL_GEN(i915) >= 7 &&
>> -        !(IS_VALLEYVIEW(i915) || IS_CHERRYVIEW(i915)))
>> +    if (!HAS_MAPPABLE_APERTURE(i915))
>> +        num_fences = 0;
>> +    else if (INTEL_GEN(i915) >= 7 &&
>> +         !(IS_VALLEYVIEW(i915) || IS_CHERRYVIEW(i915)))
>>           num_fences = 32;
>>       else if (INTEL_GEN(i915) >= 4 ||
>>            IS_I945G(i915) || IS_I945GM(i915) ||
>>
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