[PATCH 1/3] drm/i915: implement dma buf begin_cpu_access

[Dave Airlie]

On Mon, Aug 6, 2012 at 6:52 AM, Daniel Vetter <daniel at ffwll.ch> wrote:
> On Mon, Jul 30, 2012 at 02:06:54PM +1000, Dave Airlie wrote:
>> From: Dave Airlie <airlied at redhat.com>
>>
>> In order for udl vmap to work properly, we need to push the object
>> into the CPU domain before we start copying the data to the USB device.
>>
>> question: what is direction here in terms of read/write to the device.
>>
>> This along with the udl change avoids userspace explicit mapping to
>> be used.
>>
>> Signed-off-by: Dave Airlie <airlied at redhat.com>
>
> In my understanding TO_DEVICE means cpu writes, devices reads. FROM is
> devices writes, cpu reads. So your patch looks correct.
>
> One thing I wonder is how much lockdep likes this one here ... But I guess
> it's not the first one ;-) Also, do we have a simple testcase that clears
> the bo with the intel igd and then tells udl the updated damage, just to
> exercise the code a bit?

no more lockdep that previously, which is to say one big splat.

I have real code to exercise the code a bit :-), but I'll try and add
another test to my intel-gpu-tools branches this week,

Dave.