lkml.org 
[lkml]   [2022]   [Jun]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: DMA-buf and uncached system memory
From
Hi

Am 23.06.22 um 10:26 schrieb Christian König:
> Am 23.06.22 um 10:13 schrieb Thomas Zimmermann:
>> Hi Christian
>>
>> Am 15.02.21 um 09:58 schrieb Christian König:
>>> Hi guys,
>>>
>>> we are currently working an Freesync and direct scan out from system
>>> memory on AMD APUs in A+A laptops.
>>>
>>> On problem we stumbled over is that our display hardware needs to
>>> scan out from uncached system memory and we currently don't have a
>>> way to communicate that through DMA-buf.
>>>
>>> For our specific use case at hand we are going to implement something
>>> driver specific, but the question is should we have something more
>>> generic for this?
>>
>> I had a patchset here that extends iosys-map (former dma-buf-map) with
>> caching information. I'll post a copy.
>
> Oh, nice. But why on iosys-map? We need that per DMA-buf.

It's returned via the dma-buf's vmap call within the iosys-map
structure. If the dma-buf moves, the following vmap calls always return
updated caching information. Maybe it's not quite what you need for
Freesync?

I'll use this for format-conversion helpers, which do some optimizations
for uncached memory.

Anyway, I have to look for that patch...

Best regards
Thomas

>
> Thanks,
> Christian.
>
>>
>> Sorry for being late to reply.
>>
>> Best regards
>> Thomas
>>
>>>
>>> After all the system memory access pattern is a PCIe extension and as
>>> such something generic.
>>>
>>> Regards,
>>> Christian.
>>> _______________________________________________
>>> dri-devel mailing list
>>> dri-devel@lists.freedesktop.org
>>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>>
>

--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev
[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2022-06-23 10:44    [W:0.067 / U:1.492 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site