lkml.org 
[lkml]   [2018]   [Jun]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: Kernel and ADM hardware roulette ( was AMD graphics performance regression in 4.15 and later )
From
Date
Am 06.06.2018 um 15:33 schrieb Gabriel C:
> 2018-06-06 14:19 GMT+02:00 Christian König <christian.koenig@amd.com>:
>> Am 06.06.2018 um 14:08 schrieb Gabriel C:
>>> [SNIP]
>>>
>>> That has nothing TODO with the driver nor the original bug you reported. The
>>> problem is that SME is active and that is currently not supported at all
>>> with a that hardware.
> Ok .. so are we playing now kernel an AMD Hardware roulette on each release ?
>
> SME was like this in kernel 4.16.x here and all worked.
>
> Also if you don't support SME at all now on that Hardware while worked before
> please add proper error handling and proper dmesg messages
> letting the user know.
>
> radeon: xxxx : SME not supported on that Hardware anymore , please
> disable SME...
> radeon: xxxx: Update your GPU < or whatever >
>
> How hard would be that ?

Yes, to be precise that isn't the job of the GFX driver to care about
such things.

It is a well known and documented limitation of SME that it is in
general mostly incompatible with GFX (or compute) hardware, and it
actually doesn't matter which hardware or driver you use.

In other words what happens is that as soon as you use GFX (or compute)
SME gets disabled transparently.

The problem is that this happens only on the DMA slow path we just
disabled because of the performance problems.

Going to propose to revert that or at least only use it when SME is
disabled.

Regards,
Christian.

\
 
 \ /
  Last update: 2018-06-06 16:29    [W:0.113 / U:11.788 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site