On 22/08/2019 13:09, Chris Wilson wrote:
Quoting Animesh Manna (2019-08-22 13:05:06)
Hi,
On 8/21/2019 11:41 PM, Chris Wilson wrote:
Quoting Animesh Manna (2019-08-21 07:32:22)
+ vma = i915_gem_object_ggtt_pin(obj, NULL, 0, 0, PIN_MAPPABLE);
Only this (currently) still requires struct_mutex
Sure will add.
Does it have to mappable? Is that the HW constraint?
Yes, as per HW design need a cpu mapped buffer to write opcode+data from
driver.
PIN_MAPPABLE refers to the iomem aperture portion of the Global GTT (i.e.
the low 64-512MiB). You never use a GGTT mmap for your CPU access, so the
placement should be entirely dictated by the DSB requirements. If you
don't need to be in the low region, don't force it to be, so we have
less congestion for the objects that have to be placed in that region.
I was doing a mini audit of what uses the aperture these days and
noticed this code has been merged in the meantime, but AFAICS this
question from Chris hasn't been answered? At least not on the mailing
list. So does it need to be in the aperture region or not?
Regards,
Tvrtko
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